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1825 lines
56 KiB
1825 lines
56 KiB
/* SPDX-License-Identifier: GPL-2.0+ */ |
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#ifndef _LINUX_XARRAY_H |
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#define _LINUX_XARRAY_H |
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/* |
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* eXtensible Arrays |
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* Copyright (c) 2017 Microsoft Corporation |
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* Author: Matthew Wilcox <[email protected]> |
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* |
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* See Documentation/core-api/xarray.rst for how to use the XArray. |
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*/ |
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#include <linux/bug.h> |
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#include <linux/compiler.h> |
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#include <linux/gfp.h> |
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#include <linux/kconfig.h> |
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#include <linux/kernel.h> |
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#include <linux/rcupdate.h> |
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#include <linux/spinlock.h> |
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#include <linux/types.h> |
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/* |
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* The bottom two bits of the entry determine how the XArray interprets |
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* the contents: |
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* |
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* 00: Pointer entry |
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* 10: Internal entry |
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* x1: Value entry or tagged pointer |
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* |
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* Attempting to store internal entries in the XArray is a bug. |
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* |
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* Most internal entries are pointers to the next node in the tree. |
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* The following internal entries have a special meaning: |
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* |
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* 0-62: Sibling entries |
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* 256: Retry entry |
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* 257: Zero entry |
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* |
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* Errors are also represented as internal entries, but use the negative |
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* space (-4094 to -2). They're never stored in the slots array; only |
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* returned by the normal API. |
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*/ |
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#define BITS_PER_XA_VALUE (BITS_PER_LONG - 1) |
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/** |
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* xa_mk_value() - Create an XArray entry from an integer. |
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* @v: Value to store in XArray. |
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* |
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* Context: Any context. |
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* Return: An entry suitable for storing in the XArray. |
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*/ |
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static inline void *xa_mk_value(unsigned long v) |
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{ |
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WARN_ON((long)v < 0); |
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return (void *)((v << 1) | 1); |
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} |
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/** |
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* xa_to_value() - Get value stored in an XArray entry. |
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* @entry: XArray entry. |
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* |
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* Context: Any context. |
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* Return: The value stored in the XArray entry. |
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*/ |
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static inline unsigned long xa_to_value(const void *entry) |
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{ |
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return (unsigned long)entry >> 1; |
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} |
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/** |
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* xa_is_value() - Determine if an entry is a value. |
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* @entry: XArray entry. |
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* |
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* Context: Any context. |
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* Return: True if the entry is a value, false if it is a pointer. |
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*/ |
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static inline bool xa_is_value(const void *entry) |
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{ |
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return (unsigned long)entry & 1; |
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} |
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/** |
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* xa_tag_pointer() - Create an XArray entry for a tagged pointer. |
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* @p: Plain pointer. |
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* @tag: Tag value (0, 1 or 3). |
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* |
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* If the user of the XArray prefers, they can tag their pointers instead |
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* of storing value entries. Three tags are available (0, 1 and 3). |
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* These are distinct from the xa_mark_t as they are not replicated up |
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* through the array and cannot be searched for. |
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* |
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* Context: Any context. |
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* Return: An XArray entry. |
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*/ |
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static inline void *xa_tag_pointer(void *p, unsigned long tag) |
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{ |
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return (void *)((unsigned long)p | tag); |
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} |
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/** |
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* xa_untag_pointer() - Turn an XArray entry into a plain pointer. |
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* @entry: XArray entry. |
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* |
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* If you have stored a tagged pointer in the XArray, call this function |
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* to get the untagged version of the pointer. |
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* |
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* Context: Any context. |
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* Return: A pointer. |
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*/ |
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static inline void *xa_untag_pointer(void *entry) |
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{ |
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return (void *)((unsigned long)entry & ~3UL); |
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} |
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/** |
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* xa_pointer_tag() - Get the tag stored in an XArray entry. |
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* @entry: XArray entry. |
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* |
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* If you have stored a tagged pointer in the XArray, call this function |
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* to get the tag of that pointer. |
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* |
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* Context: Any context. |
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* Return: A tag. |
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*/ |
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static inline unsigned int xa_pointer_tag(void *entry) |
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{ |
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return (unsigned long)entry & 3UL; |
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} |
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/* |
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* xa_mk_internal() - Create an internal entry. |
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* @v: Value to turn into an internal entry. |
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* |
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* Internal entries are used for a number of purposes. Entries 0-255 are |
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* used for sibling entries (only 0-62 are used by the current code). 256 |
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* is used for the retry entry. 257 is used for the reserved / zero entry. |
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* Negative internal entries are used to represent errnos. Node pointers |
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* are also tagged as internal entries in some situations. |
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* |
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* Context: Any context. |
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* Return: An XArray internal entry corresponding to this value. |
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*/ |
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static inline void *xa_mk_internal(unsigned long v) |
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{ |
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return (void *)((v << 2) | 2); |
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} |
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/* |
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* xa_to_internal() - Extract the value from an internal entry. |
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* @entry: XArray entry. |
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* |
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* Context: Any context. |
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* Return: The value which was stored in the internal entry. |
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*/ |
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static inline unsigned long xa_to_internal(const void *entry) |
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{ |
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return (unsigned long)entry >> 2; |
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} |
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/* |
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* xa_is_internal() - Is the entry an internal entry? |
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* @entry: XArray entry. |
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* |
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* Context: Any context. |
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* Return: %true if the entry is an internal entry. |
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*/ |
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static inline bool xa_is_internal(const void *entry) |
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{ |
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return ((unsigned long)entry & 3) == 2; |
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} |
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#define XA_ZERO_ENTRY xa_mk_internal(257) |
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/** |
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* xa_is_zero() - Is the entry a zero entry? |
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* @entry: Entry retrieved from the XArray |
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* |
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* The normal API will return NULL as the contents of a slot containing |
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* a zero entry. You can only see zero entries by using the advanced API. |
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* |
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* Return: %true if the entry is a zero entry. |
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*/ |
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static inline bool xa_is_zero(const void *entry) |
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{ |
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return unlikely(entry == XA_ZERO_ENTRY); |
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} |
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/** |
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* xa_is_err() - Report whether an XArray operation returned an error |
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* @entry: Result from calling an XArray function |
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* |
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* If an XArray operation cannot complete an operation, it will return |
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* a special value indicating an error. This function tells you |
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* whether an error occurred; xa_err() tells you which error occurred. |
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* |
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* Context: Any context. |
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* Return: %true if the entry indicates an error. |
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*/ |
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static inline bool xa_is_err(const void *entry) |
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{ |
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return unlikely(xa_is_internal(entry) && |
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entry >= xa_mk_internal(-MAX_ERRNO)); |
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} |
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/** |
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* xa_err() - Turn an XArray result into an errno. |
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* @entry: Result from calling an XArray function. |
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* |
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* If an XArray operation cannot complete an operation, it will return |
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* a special pointer value which encodes an errno. This function extracts |
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* the errno from the pointer value, or returns 0 if the pointer does not |
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* represent an errno. |
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* |
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* Context: Any context. |
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* Return: A negative errno or 0. |
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*/ |
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static inline int xa_err(void *entry) |
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{ |
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/* xa_to_internal() would not do sign extension. */ |
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if (xa_is_err(entry)) |
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return (long)entry >> 2; |
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return 0; |
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} |
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/** |
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* struct xa_limit - Represents a range of IDs. |
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* @min: The lowest ID to allocate (inclusive). |
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* @max: The maximum ID to allocate (inclusive). |
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* |
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* This structure is used either directly or via the XA_LIMIT() macro |
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* to communicate the range of IDs that are valid for allocation. |
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* Three common ranges are predefined for you: |
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* * xa_limit_32b - [0 - UINT_MAX] |
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* * xa_limit_31b - [0 - INT_MAX] |
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* * xa_limit_16b - [0 - USHRT_MAX] |
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*/ |
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struct xa_limit { |
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u32 max; |
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u32 min; |
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}; |
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#define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max } |
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#define xa_limit_32b XA_LIMIT(0, UINT_MAX) |
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#define xa_limit_31b XA_LIMIT(0, INT_MAX) |
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#define xa_limit_16b XA_LIMIT(0, USHRT_MAX) |
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typedef unsigned __bitwise xa_mark_t; |
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#define XA_MARK_0 ((__force xa_mark_t)0U) |
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#define XA_MARK_1 ((__force xa_mark_t)1U) |
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#define XA_MARK_2 ((__force xa_mark_t)2U) |
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#define XA_PRESENT ((__force xa_mark_t)8U) |
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#define XA_MARK_MAX XA_MARK_2 |
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#define XA_FREE_MARK XA_MARK_0 |
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enum xa_lock_type { |
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XA_LOCK_IRQ = 1, |
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XA_LOCK_BH = 2, |
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}; |
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/* |
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* Values for xa_flags. The radix tree stores its GFP flags in the xa_flags, |
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* and we remain compatible with that. |
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*/ |
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#define XA_FLAGS_LOCK_IRQ ((__force gfp_t)XA_LOCK_IRQ) |
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#define XA_FLAGS_LOCK_BH ((__force gfp_t)XA_LOCK_BH) |
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#define XA_FLAGS_TRACK_FREE ((__force gfp_t)4U) |
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#define XA_FLAGS_ZERO_BUSY ((__force gfp_t)8U) |
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#define XA_FLAGS_ALLOC_WRAPPED ((__force gfp_t)16U) |
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#define XA_FLAGS_ACCOUNT ((__force gfp_t)32U) |
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#define XA_FLAGS_MARK(mark) ((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \ |
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(__force unsigned)(mark))) |
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/* ALLOC is for a normal 0-based alloc. ALLOC1 is for an 1-based alloc */ |
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#define XA_FLAGS_ALLOC (XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK)) |
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#define XA_FLAGS_ALLOC1 (XA_FLAGS_TRACK_FREE | XA_FLAGS_ZERO_BUSY) |
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/** |
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* struct xarray - The anchor of the XArray. |
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* @xa_lock: Lock that protects the contents of the XArray. |
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* |
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* To use the xarray, define it statically or embed it in your data structure. |
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* It is a very small data structure, so it does not usually make sense to |
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* allocate it separately and keep a pointer to it in your data structure. |
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* |
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* You may use the xa_lock to protect your own data structures as well. |
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*/ |
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/* |
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* If all of the entries in the array are NULL, @xa_head is a NULL pointer. |
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* If the only non-NULL entry in the array is at index 0, @xa_head is that |
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* entry. If any other entry in the array is non-NULL, @xa_head points |
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* to an @xa_node. |
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*/ |
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struct xarray { |
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spinlock_t xa_lock; |
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/* private: The rest of the data structure is not to be used directly. */ |
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gfp_t xa_flags; |
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void __rcu * xa_head; |
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}; |
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#define XARRAY_INIT(name, flags) { \ |
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.xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock), \ |
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.xa_flags = flags, \ |
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.xa_head = NULL, \ |
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} |
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/** |
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* DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags. |
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* @name: A string that names your XArray. |
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* @flags: XA_FLAG values. |
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* |
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* This is intended for file scope definitions of XArrays. It declares |
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* and initialises an empty XArray with the chosen name and flags. It is |
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* equivalent to calling xa_init_flags() on the array, but it does the |
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* initialisation at compiletime instead of runtime. |
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*/ |
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#define DEFINE_XARRAY_FLAGS(name, flags) \ |
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struct xarray name = XARRAY_INIT(name, flags) |
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/** |
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* DEFINE_XARRAY() - Define an XArray. |
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* @name: A string that names your XArray. |
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* |
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* This is intended for file scope definitions of XArrays. It declares |
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* and initialises an empty XArray with the chosen name. It is equivalent |
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* to calling xa_init() on the array, but it does the initialisation at |
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* compiletime instead of runtime. |
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*/ |
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#define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0) |
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/** |
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* DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0. |
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* @name: A string that names your XArray. |
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* |
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* This is intended for file scope definitions of allocating XArrays. |
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* See also DEFINE_XARRAY(). |
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*/ |
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#define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC) |
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/** |
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* DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1. |
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* @name: A string that names your XArray. |
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* |
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* This is intended for file scope definitions of allocating XArrays. |
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* See also DEFINE_XARRAY(). |
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*/ |
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#define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1) |
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void *xa_load(struct xarray *, unsigned long index); |
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void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t); |
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void *xa_erase(struct xarray *, unsigned long index); |
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void *xa_store_range(struct xarray *, unsigned long first, unsigned long last, |
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void *entry, gfp_t); |
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bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t); |
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void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t); |
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void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t); |
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void *xa_find(struct xarray *xa, unsigned long *index, |
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unsigned long max, xa_mark_t) __attribute__((nonnull(2))); |
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void *xa_find_after(struct xarray *xa, unsigned long *index, |
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unsigned long max, xa_mark_t) __attribute__((nonnull(2))); |
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unsigned int xa_extract(struct xarray *, void **dst, unsigned long start, |
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unsigned long max, unsigned int n, xa_mark_t); |
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void xa_destroy(struct xarray *); |
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/** |
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* xa_init_flags() - Initialise an empty XArray with flags. |
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* @xa: XArray. |
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* @flags: XA_FLAG values. |
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* |
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* If you need to initialise an XArray with special flags (eg you need |
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* to take the lock from interrupt context), use this function instead |
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* of xa_init(). |
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* |
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* Context: Any context. |
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*/ |
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static inline void xa_init_flags(struct xarray *xa, gfp_t flags) |
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{ |
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spin_lock_init(&xa->xa_lock); |
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xa->xa_flags = flags; |
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xa->xa_head = NULL; |
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} |
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/** |
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* xa_init() - Initialise an empty XArray. |
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* @xa: XArray. |
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* |
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* An empty XArray is full of NULL entries. |
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* |
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* Context: Any context. |
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*/ |
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static inline void xa_init(struct xarray *xa) |
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{ |
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xa_init_flags(xa, 0); |
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} |
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/** |
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* xa_empty() - Determine if an array has any present entries. |
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* @xa: XArray. |
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* |
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* Context: Any context. |
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* Return: %true if the array contains only NULL pointers. |
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*/ |
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static inline bool xa_empty(const struct xarray *xa) |
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{ |
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return xa->xa_head == NULL; |
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} |
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/** |
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* xa_marked() - Inquire whether any entry in this array has a mark set |
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* @xa: Array |
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* @mark: Mark value |
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* |
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* Context: Any context. |
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* Return: %true if any entry has this mark set. |
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*/ |
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static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark) |
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{ |
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return xa->xa_flags & XA_FLAGS_MARK(mark); |
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} |
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/** |
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* xa_for_each_range() - Iterate over a portion of an XArray. |
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* @xa: XArray. |
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* @index: Index of @entry. |
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* @entry: Entry retrieved from array. |
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* @start: First index to retrieve from array. |
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* @last: Last index to retrieve from array. |
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* |
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* During the iteration, @entry will have the value of the entry stored |
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* in @xa at @index. You may modify @index during the iteration if you |
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* want to skip or reprocess indices. It is safe to modify the array |
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* during the iteration. At the end of the iteration, @entry will be set |
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* to NULL and @index will have a value less than or equal to max. |
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* |
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* xa_for_each_range() is O(n.log(n)) while xas_for_each() is O(n). You have |
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* to handle your own locking with xas_for_each(), and if you have to unlock |
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* after each iteration, it will also end up being O(n.log(n)). |
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* xa_for_each_range() will spin if it hits a retry entry; if you intend to |
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* see retry entries, you should use the xas_for_each() iterator instead. |
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* The xas_for_each() iterator will expand into more inline code than |
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* xa_for_each_range(). |
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* |
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* Context: Any context. Takes and releases the RCU lock. |
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*/ |
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#define xa_for_each_range(xa, index, entry, start, last) \ |
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for (index = start, \ |
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entry = xa_find(xa, &index, last, XA_PRESENT); \ |
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entry; \ |
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entry = xa_find_after(xa, &index, last, XA_PRESENT)) |
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|
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/** |
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* xa_for_each_start() - Iterate over a portion of an XArray. |
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* @xa: XArray. |
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* @index: Index of @entry. |
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* @entry: Entry retrieved from array. |
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* @start: First index to retrieve from array. |
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* |
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* During the iteration, @entry will have the value of the entry stored |
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* in @xa at @index. You may modify @index during the iteration if you |
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* want to skip or reprocess indices. It is safe to modify the array |
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* during the iteration. At the end of the iteration, @entry will be set |
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* to NULL and @index will have a value less than or equal to max. |
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* |
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* xa_for_each_start() is O(n.log(n)) while xas_for_each() is O(n). You have |
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* to handle your own locking with xas_for_each(), and if you have to unlock |
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* after each iteration, it will also end up being O(n.log(n)). |
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* xa_for_each_start() will spin if it hits a retry entry; if you intend to |
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* see retry entries, you should use the xas_for_each() iterator instead. |
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* The xas_for_each() iterator will expand into more inline code than |
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* xa_for_each_start(). |
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* |
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* Context: Any context. Takes and releases the RCU lock. |
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*/ |
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#define xa_for_each_start(xa, index, entry, start) \ |
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xa_for_each_range(xa, index, entry, start, ULONG_MAX) |
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|
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/** |
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* xa_for_each() - Iterate over present entries in an XArray. |
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* @xa: XArray. |
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* @index: Index of @entry. |
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* @entry: Entry retrieved from array. |
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* |
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* During the iteration, @entry will have the value of the entry stored |
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* in @xa at @index. You may modify @index during the iteration if you want |
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* to skip or reprocess indices. It is safe to modify the array during the |
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* iteration. At the end of the iteration, @entry will be set to NULL and |
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* @index will have a value less than or equal to max. |
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* |
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* xa_for_each() is O(n.log(n)) while xas_for_each() is O(n). You have |
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* to handle your own locking with xas_for_each(), and if you have to unlock |
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* after each iteration, it will also end up being O(n.log(n)). xa_for_each() |
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* will spin if it hits a retry entry; if you intend to see retry entries, |
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* you should use the xas_for_each() iterator instead. The xas_for_each() |
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* iterator will expand into more inline code than xa_for_each(). |
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* |
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* Context: Any context. Takes and releases the RCU lock. |
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*/ |
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#define xa_for_each(xa, index, entry) \ |
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xa_for_each_start(xa, index, entry, 0) |
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|
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/** |
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* xa_for_each_marked() - Iterate over marked entries in an XArray. |
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* @xa: XArray. |
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* @index: Index of @entry. |
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* @entry: Entry retrieved from array. |
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* @filter: Selection criterion. |
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* |
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* During the iteration, @entry will have the value of the entry stored |
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* in @xa at @index. The iteration will skip all entries in the array |
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* which do not match @filter. You may modify @index during the iteration |
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* if you want to skip or reprocess indices. It is safe to modify the array |
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* during the iteration. At the end of the iteration, @entry will be set to |
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* NULL and @index will have a value less than or equal to max. |
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* |
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* xa_for_each_marked() is O(n.log(n)) while xas_for_each_marked() is O(n). |
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* You have to handle your own locking with xas_for_each(), and if you have |
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* to unlock after each iteration, it will also end up being O(n.log(n)). |
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* xa_for_each_marked() will spin if it hits a retry entry; if you intend to |
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* see retry entries, you should use the xas_for_each_marked() iterator |
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* instead. The xas_for_each_marked() iterator will expand into more inline |
|
* code than xa_for_each_marked(). |
|
* |
|
* Context: Any context. Takes and releases the RCU lock. |
|
*/ |
|
#define xa_for_each_marked(xa, index, entry, filter) \ |
|
for (index = 0, entry = xa_find(xa, &index, ULONG_MAX, filter); \ |
|
entry; entry = xa_find_after(xa, &index, ULONG_MAX, filter)) |
|
|
|
#define xa_trylock(xa) spin_trylock(&(xa)->xa_lock) |
|
#define xa_lock(xa) spin_lock(&(xa)->xa_lock) |
|
#define xa_unlock(xa) spin_unlock(&(xa)->xa_lock) |
|
#define xa_lock_bh(xa) spin_lock_bh(&(xa)->xa_lock) |
|
#define xa_unlock_bh(xa) spin_unlock_bh(&(xa)->xa_lock) |
|
#define xa_lock_irq(xa) spin_lock_irq(&(xa)->xa_lock) |
|
#define xa_unlock_irq(xa) spin_unlock_irq(&(xa)->xa_lock) |
|
#define xa_lock_irqsave(xa, flags) \ |
|
spin_lock_irqsave(&(xa)->xa_lock, flags) |
|
#define xa_unlock_irqrestore(xa, flags) \ |
|
spin_unlock_irqrestore(&(xa)->xa_lock, flags) |
|
#define xa_lock_nested(xa, subclass) \ |
|
spin_lock_nested(&(xa)->xa_lock, subclass) |
|
#define xa_lock_bh_nested(xa, subclass) \ |
|
spin_lock_bh_nested(&(xa)->xa_lock, subclass) |
|
#define xa_lock_irq_nested(xa, subclass) \ |
|
spin_lock_irq_nested(&(xa)->xa_lock, subclass) |
|
#define xa_lock_irqsave_nested(xa, flags, subclass) \ |
|
spin_lock_irqsave_nested(&(xa)->xa_lock, flags, subclass) |
|
|
|
/* |
|
* Versions of the normal API which require the caller to hold the |
|
* xa_lock. If the GFP flags allow it, they will drop the lock to |
|
* allocate memory, then reacquire it afterwards. These functions |
|
* may also re-enable interrupts if the XArray flags indicate the |
|
* locking should be interrupt safe. |
|
*/ |
|
void *__xa_erase(struct xarray *, unsigned long index); |
|
void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t); |
|
void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old, |
|
void *entry, gfp_t); |
|
int __must_check __xa_insert(struct xarray *, unsigned long index, |
|
void *entry, gfp_t); |
|
int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry, |
|
struct xa_limit, gfp_t); |
|
int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry, |
|
struct xa_limit, u32 *next, gfp_t); |
|
void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t); |
|
void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t); |
|
|
|
/** |
|
* xa_store_bh() - Store this entry in the XArray. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @entry: New entry. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* This function is like calling xa_store() except it disables softirqs |
|
* while holding the array lock. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock while |
|
* disabling softirqs. |
|
* Return: The old entry at this index or xa_err() if an error happened. |
|
*/ |
|
static inline void *xa_store_bh(struct xarray *xa, unsigned long index, |
|
void *entry, gfp_t gfp) |
|
{ |
|
void *curr; |
|
|
|
xa_lock_bh(xa); |
|
curr = __xa_store(xa, index, entry, gfp); |
|
xa_unlock_bh(xa); |
|
|
|
return curr; |
|
} |
|
|
|
/** |
|
* xa_store_irq() - Store this entry in the XArray. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @entry: New entry. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* This function is like calling xa_store() except it disables interrupts |
|
* while holding the array lock. |
|
* |
|
* Context: Process context. Takes and releases the xa_lock while |
|
* disabling interrupts. |
|
* Return: The old entry at this index or xa_err() if an error happened. |
|
*/ |
|
static inline void *xa_store_irq(struct xarray *xa, unsigned long index, |
|
void *entry, gfp_t gfp) |
|
{ |
|
void *curr; |
|
|
|
xa_lock_irq(xa); |
|
curr = __xa_store(xa, index, entry, gfp); |
|
xa_unlock_irq(xa); |
|
|
|
return curr; |
|
} |
|
|
|
/** |
|
* xa_erase_bh() - Erase this entry from the XArray. |
|
* @xa: XArray. |
|
* @index: Index of entry. |
|
* |
|
* After this function returns, loading from @index will return %NULL. |
|
* If the index is part of a multi-index entry, all indices will be erased |
|
* and none of the entries will be part of a multi-index entry. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock while |
|
* disabling softirqs. |
|
* Return: The entry which used to be at this index. |
|
*/ |
|
static inline void *xa_erase_bh(struct xarray *xa, unsigned long index) |
|
{ |
|
void *entry; |
|
|
|
xa_lock_bh(xa); |
|
entry = __xa_erase(xa, index); |
|
xa_unlock_bh(xa); |
|
|
|
return entry; |
|
} |
|
|
|
/** |
|
* xa_erase_irq() - Erase this entry from the XArray. |
|
* @xa: XArray. |
|
* @index: Index of entry. |
|
* |
|
* After this function returns, loading from @index will return %NULL. |
|
* If the index is part of a multi-index entry, all indices will be erased |
|
* and none of the entries will be part of a multi-index entry. |
|
* |
|
* Context: Process context. Takes and releases the xa_lock while |
|
* disabling interrupts. |
|
* Return: The entry which used to be at this index. |
|
*/ |
|
static inline void *xa_erase_irq(struct xarray *xa, unsigned long index) |
|
{ |
|
void *entry; |
|
|
|
xa_lock_irq(xa); |
|
entry = __xa_erase(xa, index); |
|
xa_unlock_irq(xa); |
|
|
|
return entry; |
|
} |
|
|
|
/** |
|
* xa_cmpxchg() - Conditionally replace an entry in the XArray. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @old: Old value to test against. |
|
* @entry: New value to place in array. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* If the entry at @index is the same as @old, replace it with @entry. |
|
* If the return value is equal to @old, then the exchange was successful. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock. May sleep |
|
* if the @gfp flags permit. |
|
* Return: The old value at this index or xa_err() if an error happened. |
|
*/ |
|
static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index, |
|
void *old, void *entry, gfp_t gfp) |
|
{ |
|
void *curr; |
|
|
|
xa_lock(xa); |
|
curr = __xa_cmpxchg(xa, index, old, entry, gfp); |
|
xa_unlock(xa); |
|
|
|
return curr; |
|
} |
|
|
|
/** |
|
* xa_cmpxchg_bh() - Conditionally replace an entry in the XArray. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @old: Old value to test against. |
|
* @entry: New value to place in array. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* This function is like calling xa_cmpxchg() except it disables softirqs |
|
* while holding the array lock. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock while |
|
* disabling softirqs. May sleep if the @gfp flags permit. |
|
* Return: The old value at this index or xa_err() if an error happened. |
|
*/ |
|
static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index, |
|
void *old, void *entry, gfp_t gfp) |
|
{ |
|
void *curr; |
|
|
|
xa_lock_bh(xa); |
|
curr = __xa_cmpxchg(xa, index, old, entry, gfp); |
|
xa_unlock_bh(xa); |
|
|
|
return curr; |
|
} |
|
|
|
/** |
|
* xa_cmpxchg_irq() - Conditionally replace an entry in the XArray. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @old: Old value to test against. |
|
* @entry: New value to place in array. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* This function is like calling xa_cmpxchg() except it disables interrupts |
|
* while holding the array lock. |
|
* |
|
* Context: Process context. Takes and releases the xa_lock while |
|
* disabling interrupts. May sleep if the @gfp flags permit. |
|
* Return: The old value at this index or xa_err() if an error happened. |
|
*/ |
|
static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index, |
|
void *old, void *entry, gfp_t gfp) |
|
{ |
|
void *curr; |
|
|
|
xa_lock_irq(xa); |
|
curr = __xa_cmpxchg(xa, index, old, entry, gfp); |
|
xa_unlock_irq(xa); |
|
|
|
return curr; |
|
} |
|
|
|
/** |
|
* xa_insert() - Store this entry in the XArray unless another entry is |
|
* already present. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @entry: New entry. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* Inserting a NULL entry will store a reserved entry (like xa_reserve()) |
|
* if no entry is present. Inserting will fail if a reserved entry is |
|
* present, even though loading from this index will return NULL. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock. May sleep if |
|
* the @gfp flags permit. |
|
* Return: 0 if the store succeeded. -EBUSY if another entry was present. |
|
* -ENOMEM if memory could not be allocated. |
|
*/ |
|
static inline int __must_check xa_insert(struct xarray *xa, |
|
unsigned long index, void *entry, gfp_t gfp) |
|
{ |
|
int err; |
|
|
|
xa_lock(xa); |
|
err = __xa_insert(xa, index, entry, gfp); |
|
xa_unlock(xa); |
|
|
|
return err; |
|
} |
|
|
|
/** |
|
* xa_insert_bh() - Store this entry in the XArray unless another entry is |
|
* already present. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @entry: New entry. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* Inserting a NULL entry will store a reserved entry (like xa_reserve()) |
|
* if no entry is present. Inserting will fail if a reserved entry is |
|
* present, even though loading from this index will return NULL. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock while |
|
* disabling softirqs. May sleep if the @gfp flags permit. |
|
* Return: 0 if the store succeeded. -EBUSY if another entry was present. |
|
* -ENOMEM if memory could not be allocated. |
|
*/ |
|
static inline int __must_check xa_insert_bh(struct xarray *xa, |
|
unsigned long index, void *entry, gfp_t gfp) |
|
{ |
|
int err; |
|
|
|
xa_lock_bh(xa); |
|
err = __xa_insert(xa, index, entry, gfp); |
|
xa_unlock_bh(xa); |
|
|
|
return err; |
|
} |
|
|
|
/** |
|
* xa_insert_irq() - Store this entry in the XArray unless another entry is |
|
* already present. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @entry: New entry. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* Inserting a NULL entry will store a reserved entry (like xa_reserve()) |
|
* if no entry is present. Inserting will fail if a reserved entry is |
|
* present, even though loading from this index will return NULL. |
|
* |
|
* Context: Process context. Takes and releases the xa_lock while |
|
* disabling interrupts. May sleep if the @gfp flags permit. |
|
* Return: 0 if the store succeeded. -EBUSY if another entry was present. |
|
* -ENOMEM if memory could not be allocated. |
|
*/ |
|
static inline int __must_check xa_insert_irq(struct xarray *xa, |
|
unsigned long index, void *entry, gfp_t gfp) |
|
{ |
|
int err; |
|
|
|
xa_lock_irq(xa); |
|
err = __xa_insert(xa, index, entry, gfp); |
|
xa_unlock_irq(xa); |
|
|
|
return err; |
|
} |
|
|
|
/** |
|
* xa_alloc() - Find somewhere to store this entry in the XArray. |
|
* @xa: XArray. |
|
* @id: Pointer to ID. |
|
* @entry: New entry. |
|
* @limit: Range of ID to allocate. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* Finds an empty entry in @xa between @limit.min and @limit.max, |
|
* stores the index into the @id pointer, then stores the entry at |
|
* that index. A concurrent lookup will not see an uninitialised @id. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock. May sleep if |
|
* the @gfp flags permit. |
|
* Return: 0 on success, -ENOMEM if memory could not be allocated or |
|
* -EBUSY if there are no free entries in @limit. |
|
*/ |
|
static inline __must_check int xa_alloc(struct xarray *xa, u32 *id, |
|
void *entry, struct xa_limit limit, gfp_t gfp) |
|
{ |
|
int err; |
|
|
|
xa_lock(xa); |
|
err = __xa_alloc(xa, id, entry, limit, gfp); |
|
xa_unlock(xa); |
|
|
|
return err; |
|
} |
|
|
|
/** |
|
* xa_alloc_bh() - Find somewhere to store this entry in the XArray. |
|
* @xa: XArray. |
|
* @id: Pointer to ID. |
|
* @entry: New entry. |
|
* @limit: Range of ID to allocate. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* Finds an empty entry in @xa between @limit.min and @limit.max, |
|
* stores the index into the @id pointer, then stores the entry at |
|
* that index. A concurrent lookup will not see an uninitialised @id. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock while |
|
* disabling softirqs. May sleep if the @gfp flags permit. |
|
* Return: 0 on success, -ENOMEM if memory could not be allocated or |
|
* -EBUSY if there are no free entries in @limit. |
|
*/ |
|
static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id, |
|
void *entry, struct xa_limit limit, gfp_t gfp) |
|
{ |
|
int err; |
|
|
|
xa_lock_bh(xa); |
|
err = __xa_alloc(xa, id, entry, limit, gfp); |
|
xa_unlock_bh(xa); |
|
|
|
return err; |
|
} |
|
|
|
/** |
|
* xa_alloc_irq() - Find somewhere to store this entry in the XArray. |
|
* @xa: XArray. |
|
* @id: Pointer to ID. |
|
* @entry: New entry. |
|
* @limit: Range of ID to allocate. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* Finds an empty entry in @xa between @limit.min and @limit.max, |
|
* stores the index into the @id pointer, then stores the entry at |
|
* that index. A concurrent lookup will not see an uninitialised @id. |
|
* |
|
* Context: Process context. Takes and releases the xa_lock while |
|
* disabling interrupts. May sleep if the @gfp flags permit. |
|
* Return: 0 on success, -ENOMEM if memory could not be allocated or |
|
* -EBUSY if there are no free entries in @limit. |
|
*/ |
|
static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id, |
|
void *entry, struct xa_limit limit, gfp_t gfp) |
|
{ |
|
int err; |
|
|
|
xa_lock_irq(xa); |
|
err = __xa_alloc(xa, id, entry, limit, gfp); |
|
xa_unlock_irq(xa); |
|
|
|
return err; |
|
} |
|
|
|
/** |
|
* xa_alloc_cyclic() - Find somewhere to store this entry in the XArray. |
|
* @xa: XArray. |
|
* @id: Pointer to ID. |
|
* @entry: New entry. |
|
* @limit: Range of allocated ID. |
|
* @next: Pointer to next ID to allocate. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* Finds an empty entry in @xa between @limit.min and @limit.max, |
|
* stores the index into the @id pointer, then stores the entry at |
|
* that index. A concurrent lookup will not see an uninitialised @id. |
|
* The search for an empty entry will start at @next and will wrap |
|
* around if necessary. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock. May sleep if |
|
* the @gfp flags permit. |
|
* Return: 0 if the allocation succeeded without wrapping. 1 if the |
|
* allocation succeeded after wrapping, -ENOMEM if memory could not be |
|
* allocated or -EBUSY if there are no free entries in @limit. |
|
*/ |
|
static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry, |
|
struct xa_limit limit, u32 *next, gfp_t gfp) |
|
{ |
|
int err; |
|
|
|
xa_lock(xa); |
|
err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp); |
|
xa_unlock(xa); |
|
|
|
return err; |
|
} |
|
|
|
/** |
|
* xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray. |
|
* @xa: XArray. |
|
* @id: Pointer to ID. |
|
* @entry: New entry. |
|
* @limit: Range of allocated ID. |
|
* @next: Pointer to next ID to allocate. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* Finds an empty entry in @xa between @limit.min and @limit.max, |
|
* stores the index into the @id pointer, then stores the entry at |
|
* that index. A concurrent lookup will not see an uninitialised @id. |
|
* The search for an empty entry will start at @next and will wrap |
|
* around if necessary. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock while |
|
* disabling softirqs. May sleep if the @gfp flags permit. |
|
* Return: 0 if the allocation succeeded without wrapping. 1 if the |
|
* allocation succeeded after wrapping, -ENOMEM if memory could not be |
|
* allocated or -EBUSY if there are no free entries in @limit. |
|
*/ |
|
static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry, |
|
struct xa_limit limit, u32 *next, gfp_t gfp) |
|
{ |
|
int err; |
|
|
|
xa_lock_bh(xa); |
|
err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp); |
|
xa_unlock_bh(xa); |
|
|
|
return err; |
|
} |
|
|
|
/** |
|
* xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray. |
|
* @xa: XArray. |
|
* @id: Pointer to ID. |
|
* @entry: New entry. |
|
* @limit: Range of allocated ID. |
|
* @next: Pointer to next ID to allocate. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* Finds an empty entry in @xa between @limit.min and @limit.max, |
|
* stores the index into the @id pointer, then stores the entry at |
|
* that index. A concurrent lookup will not see an uninitialised @id. |
|
* The search for an empty entry will start at @next and will wrap |
|
* around if necessary. |
|
* |
|
* Context: Process context. Takes and releases the xa_lock while |
|
* disabling interrupts. May sleep if the @gfp flags permit. |
|
* Return: 0 if the allocation succeeded without wrapping. 1 if the |
|
* allocation succeeded after wrapping, -ENOMEM if memory could not be |
|
* allocated or -EBUSY if there are no free entries in @limit. |
|
*/ |
|
static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry, |
|
struct xa_limit limit, u32 *next, gfp_t gfp) |
|
{ |
|
int err; |
|
|
|
xa_lock_irq(xa); |
|
err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp); |
|
xa_unlock_irq(xa); |
|
|
|
return err; |
|
} |
|
|
|
/** |
|
* xa_reserve() - Reserve this index in the XArray. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* Ensures there is somewhere to store an entry at @index in the array. |
|
* If there is already something stored at @index, this function does |
|
* nothing. If there was nothing there, the entry is marked as reserved. |
|
* Loading from a reserved entry returns a %NULL pointer. |
|
* |
|
* If you do not use the entry that you have reserved, call xa_release() |
|
* or xa_erase() to free any unnecessary memory. |
|
* |
|
* Context: Any context. Takes and releases the xa_lock. |
|
* May sleep if the @gfp flags permit. |
|
* Return: 0 if the reservation succeeded or -ENOMEM if it failed. |
|
*/ |
|
static inline __must_check |
|
int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp) |
|
{ |
|
return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp)); |
|
} |
|
|
|
/** |
|
* xa_reserve_bh() - Reserve this index in the XArray. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* A softirq-disabling version of xa_reserve(). |
|
* |
|
* Context: Any context. Takes and releases the xa_lock while |
|
* disabling softirqs. |
|
* Return: 0 if the reservation succeeded or -ENOMEM if it failed. |
|
*/ |
|
static inline __must_check |
|
int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp) |
|
{ |
|
return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp)); |
|
} |
|
|
|
/** |
|
* xa_reserve_irq() - Reserve this index in the XArray. |
|
* @xa: XArray. |
|
* @index: Index into array. |
|
* @gfp: Memory allocation flags. |
|
* |
|
* An interrupt-disabling version of xa_reserve(). |
|
* |
|
* Context: Process context. Takes and releases the xa_lock while |
|
* disabling interrupts. |
|
* Return: 0 if the reservation succeeded or -ENOMEM if it failed. |
|
*/ |
|
static inline __must_check |
|
int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp) |
|
{ |
|
return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp)); |
|
} |
|
|
|
/** |
|
* xa_release() - Release a reserved entry. |
|
* @xa: XArray. |
|
* @index: Index of entry. |
|
* |
|
* After calling xa_reserve(), you can call this function to release the |
|
* reservation. If the entry at @index has been stored to, this function |
|
* will do nothing. |
|
*/ |
|
static inline void xa_release(struct xarray *xa, unsigned long index) |
|
{ |
|
xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0); |
|
} |
|
|
|
/* Everything below here is the Advanced API. Proceed with caution. */ |
|
|
|
/* |
|
* The xarray is constructed out of a set of 'chunks' of pointers. Choosing |
|
* the best chunk size requires some tradeoffs. A power of two recommends |
|
* itself so that we can walk the tree based purely on shifts and masks. |
|
* Generally, the larger the better; as the number of slots per level of the |
|
* tree increases, the less tall the tree needs to be. But that needs to be |
|
* balanced against the memory consumption of each node. On a 64-bit system, |
|
* xa_node is currently 576 bytes, and we get 7 of them per 4kB page. If we |
|
* doubled the number of slots per node, we'd get only 3 nodes per 4kB page. |
|
*/ |
|
#ifndef XA_CHUNK_SHIFT |
|
#define XA_CHUNK_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) |
|
#endif |
|
#define XA_CHUNK_SIZE (1UL << XA_CHUNK_SHIFT) |
|
#define XA_CHUNK_MASK (XA_CHUNK_SIZE - 1) |
|
#define XA_MAX_MARKS 3 |
|
#define XA_MARK_LONGS DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG) |
|
|
|
/* |
|
* @count is the count of every non-NULL element in the ->slots array |
|
* whether that is a value entry, a retry entry, a user pointer, |
|
* a sibling entry or a pointer to the next level of the tree. |
|
* @nr_values is the count of every element in ->slots which is |
|
* either a value entry or a sibling of a value entry. |
|
*/ |
|
struct xa_node { |
|
unsigned char shift; /* Bits remaining in each slot */ |
|
unsigned char offset; /* Slot offset in parent */ |
|
unsigned char count; /* Total entry count */ |
|
unsigned char nr_values; /* Value entry count */ |
|
struct xa_node __rcu *parent; /* NULL at top of tree */ |
|
struct xarray *array; /* The array we belong to */ |
|
union { |
|
struct list_head private_list; /* For tree user */ |
|
struct rcu_head rcu_head; /* Used when freeing node */ |
|
}; |
|
void __rcu *slots[XA_CHUNK_SIZE]; |
|
union { |
|
unsigned long tags[XA_MAX_MARKS][XA_MARK_LONGS]; |
|
unsigned long marks[XA_MAX_MARKS][XA_MARK_LONGS]; |
|
}; |
|
}; |
|
|
|
void xa_dump(const struct xarray *); |
|
void xa_dump_node(const struct xa_node *); |
|
|
|
#ifdef XA_DEBUG |
|
#define XA_BUG_ON(xa, x) do { \ |
|
if (x) { \ |
|
xa_dump(xa); \ |
|
BUG(); \ |
|
} \ |
|
} while (0) |
|
#define XA_NODE_BUG_ON(node, x) do { \ |
|
if (x) { \ |
|
if (node) xa_dump_node(node); \ |
|
BUG(); \ |
|
} \ |
|
} while (0) |
|
#else |
|
#define XA_BUG_ON(xa, x) do { } while (0) |
|
#define XA_NODE_BUG_ON(node, x) do { } while (0) |
|
#endif |
|
|
|
/* Private */ |
|
static inline void *xa_head(const struct xarray *xa) |
|
{ |
|
return rcu_dereference_check(xa->xa_head, |
|
lockdep_is_held(&xa->xa_lock)); |
|
} |
|
|
|
/* Private */ |
|
static inline void *xa_head_locked(const struct xarray *xa) |
|
{ |
|
return rcu_dereference_protected(xa->xa_head, |
|
lockdep_is_held(&xa->xa_lock)); |
|
} |
|
|
|
/* Private */ |
|
static inline void *xa_entry(const struct xarray *xa, |
|
const struct xa_node *node, unsigned int offset) |
|
{ |
|
XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE); |
|
return rcu_dereference_check(node->slots[offset], |
|
lockdep_is_held(&xa->xa_lock)); |
|
} |
|
|
|
/* Private */ |
|
static inline void *xa_entry_locked(const struct xarray *xa, |
|
const struct xa_node *node, unsigned int offset) |
|
{ |
|
XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE); |
|
return rcu_dereference_protected(node->slots[offset], |
|
lockdep_is_held(&xa->xa_lock)); |
|
} |
|
|
|
/* Private */ |
|
static inline struct xa_node *xa_parent(const struct xarray *xa, |
|
const struct xa_node *node) |
|
{ |
|
return rcu_dereference_check(node->parent, |
|
lockdep_is_held(&xa->xa_lock)); |
|
} |
|
|
|
/* Private */ |
|
static inline struct xa_node *xa_parent_locked(const struct xarray *xa, |
|
const struct xa_node *node) |
|
{ |
|
return rcu_dereference_protected(node->parent, |
|
lockdep_is_held(&xa->xa_lock)); |
|
} |
|
|
|
/* Private */ |
|
static inline void *xa_mk_node(const struct xa_node *node) |
|
{ |
|
return (void *)((unsigned long)node | 2); |
|
} |
|
|
|
/* Private */ |
|
static inline struct xa_node *xa_to_node(const void *entry) |
|
{ |
|
return (struct xa_node *)((unsigned long)entry - 2); |
|
} |
|
|
|
/* Private */ |
|
static inline bool xa_is_node(const void *entry) |
|
{ |
|
return xa_is_internal(entry) && (unsigned long)entry > 4096; |
|
} |
|
|
|
/* Private */ |
|
static inline void *xa_mk_sibling(unsigned int offset) |
|
{ |
|
return xa_mk_internal(offset); |
|
} |
|
|
|
/* Private */ |
|
static inline unsigned long xa_to_sibling(const void *entry) |
|
{ |
|
return xa_to_internal(entry); |
|
} |
|
|
|
/** |
|
* xa_is_sibling() - Is the entry a sibling entry? |
|
* @entry: Entry retrieved from the XArray |
|
* |
|
* Return: %true if the entry is a sibling entry. |
|
*/ |
|
static inline bool xa_is_sibling(const void *entry) |
|
{ |
|
return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) && |
|
(entry < xa_mk_sibling(XA_CHUNK_SIZE - 1)); |
|
} |
|
|
|
#define XA_RETRY_ENTRY xa_mk_internal(256) |
|
|
|
/** |
|
* xa_is_retry() - Is the entry a retry entry? |
|
* @entry: Entry retrieved from the XArray |
|
* |
|
* Return: %true if the entry is a retry entry. |
|
*/ |
|
static inline bool xa_is_retry(const void *entry) |
|
{ |
|
return unlikely(entry == XA_RETRY_ENTRY); |
|
} |
|
|
|
/** |
|
* xa_is_advanced() - Is the entry only permitted for the advanced API? |
|
* @entry: Entry to be stored in the XArray. |
|
* |
|
* Return: %true if the entry cannot be stored by the normal API. |
|
*/ |
|
static inline bool xa_is_advanced(const void *entry) |
|
{ |
|
return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY); |
|
} |
|
|
|
/** |
|
* typedef xa_update_node_t - A callback function from the XArray. |
|
* @node: The node which is being processed |
|
* |
|
* This function is called every time the XArray updates the count of |
|
* present and value entries in a node. It allows advanced users to |
|
* maintain the private_list in the node. |
|
* |
|
* Context: The xa_lock is held and interrupts may be disabled. |
|
* Implementations should not drop the xa_lock, nor re-enable |
|
* interrupts. |
|
*/ |
|
typedef void (*xa_update_node_t)(struct xa_node *node); |
|
|
|
void xa_delete_node(struct xa_node *, xa_update_node_t); |
|
|
|
/* |
|
* The xa_state is opaque to its users. It contains various different pieces |
|
* of state involved in the current operation on the XArray. It should be |
|
* declared on the stack and passed between the various internal routines. |
|
* The various elements in it should not be accessed directly, but only |
|
* through the provided accessor functions. The below documentation is for |
|
* the benefit of those working on the code, not for users of the XArray. |
|
* |
|
* @xa_node usually points to the xa_node containing the slot we're operating |
|
* on (and @xa_offset is the offset in the slots array). If there is a |
|
* single entry in the array at index 0, there are no allocated xa_nodes to |
|
* point to, and so we store %NULL in @xa_node. @xa_node is set to |
|
* the value %XAS_RESTART if the xa_state is not walked to the correct |
|
* position in the tree of nodes for this operation. If an error occurs |
|
* during an operation, it is set to an %XAS_ERROR value. If we run off the |
|
* end of the allocated nodes, it is set to %XAS_BOUNDS. |
|
*/ |
|
struct xa_state { |
|
struct xarray *xa; |
|
unsigned long xa_index; |
|
unsigned char xa_shift; |
|
unsigned char xa_sibs; |
|
unsigned char xa_offset; |
|
unsigned char xa_pad; /* Helps gcc generate better code */ |
|
struct xa_node *xa_node; |
|
struct xa_node *xa_alloc; |
|
xa_update_node_t xa_update; |
|
}; |
|
|
|
/* |
|
* We encode errnos in the xas->xa_node. If an error has happened, we need to |
|
* drop the lock to fix it, and once we've done so the xa_state is invalid. |
|
*/ |
|
#define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL)) |
|
#define XAS_BOUNDS ((struct xa_node *)1UL) |
|
#define XAS_RESTART ((struct xa_node *)3UL) |
|
|
|
#define __XA_STATE(array, index, shift, sibs) { \ |
|
.xa = array, \ |
|
.xa_index = index, \ |
|
.xa_shift = shift, \ |
|
.xa_sibs = sibs, \ |
|
.xa_offset = 0, \ |
|
.xa_pad = 0, \ |
|
.xa_node = XAS_RESTART, \ |
|
.xa_alloc = NULL, \ |
|
.xa_update = NULL \ |
|
} |
|
|
|
/** |
|
* XA_STATE() - Declare an XArray operation state. |
|
* @name: Name of this operation state (usually xas). |
|
* @array: Array to operate on. |
|
* @index: Initial index of interest. |
|
* |
|
* Declare and initialise an xa_state on the stack. |
|
*/ |
|
#define XA_STATE(name, array, index) \ |
|
struct xa_state name = __XA_STATE(array, index, 0, 0) |
|
|
|
/** |
|
* XA_STATE_ORDER() - Declare an XArray operation state. |
|
* @name: Name of this operation state (usually xas). |
|
* @array: Array to operate on. |
|
* @index: Initial index of interest. |
|
* @order: Order of entry. |
|
* |
|
* Declare and initialise an xa_state on the stack. This variant of |
|
* XA_STATE() allows you to specify the 'order' of the element you |
|
* want to operate on.` |
|
*/ |
|
#define XA_STATE_ORDER(name, array, index, order) \ |
|
struct xa_state name = __XA_STATE(array, \ |
|
(index >> order) << order, \ |
|
order - (order % XA_CHUNK_SHIFT), \ |
|
(1U << (order % XA_CHUNK_SHIFT)) - 1) |
|
|
|
#define xas_marked(xas, mark) xa_marked((xas)->xa, (mark)) |
|
#define xas_trylock(xas) xa_trylock((xas)->xa) |
|
#define xas_lock(xas) xa_lock((xas)->xa) |
|
#define xas_unlock(xas) xa_unlock((xas)->xa) |
|
#define xas_lock_bh(xas) xa_lock_bh((xas)->xa) |
|
#define xas_unlock_bh(xas) xa_unlock_bh((xas)->xa) |
|
#define xas_lock_irq(xas) xa_lock_irq((xas)->xa) |
|
#define xas_unlock_irq(xas) xa_unlock_irq((xas)->xa) |
|
#define xas_lock_irqsave(xas, flags) \ |
|
xa_lock_irqsave((xas)->xa, flags) |
|
#define xas_unlock_irqrestore(xas, flags) \ |
|
xa_unlock_irqrestore((xas)->xa, flags) |
|
|
|
/** |
|
* xas_error() - Return an errno stored in the xa_state. |
|
* @xas: XArray operation state. |
|
* |
|
* Return: 0 if no error has been noted. A negative errno if one has. |
|
*/ |
|
static inline int xas_error(const struct xa_state *xas) |
|
{ |
|
return xa_err(xas->xa_node); |
|
} |
|
|
|
/** |
|
* xas_set_err() - Note an error in the xa_state. |
|
* @xas: XArray operation state. |
|
* @err: Negative error number. |
|
* |
|
* Only call this function with a negative @err; zero or positive errors |
|
* will probably not behave the way you think they should. If you want |
|
* to clear the error from an xa_state, use xas_reset(). |
|
*/ |
|
static inline void xas_set_err(struct xa_state *xas, long err) |
|
{ |
|
xas->xa_node = XA_ERROR(err); |
|
} |
|
|
|
/** |
|
* xas_invalid() - Is the xas in a retry or error state? |
|
* @xas: XArray operation state. |
|
* |
|
* Return: %true if the xas cannot be used for operations. |
|
*/ |
|
static inline bool xas_invalid(const struct xa_state *xas) |
|
{ |
|
return (unsigned long)xas->xa_node & 3; |
|
} |
|
|
|
/** |
|
* xas_valid() - Is the xas a valid cursor into the array? |
|
* @xas: XArray operation state. |
|
* |
|
* Return: %true if the xas can be used for operations. |
|
*/ |
|
static inline bool xas_valid(const struct xa_state *xas) |
|
{ |
|
return !xas_invalid(xas); |
|
} |
|
|
|
/** |
|
* xas_is_node() - Does the xas point to a node? |
|
* @xas: XArray operation state. |
|
* |
|
* Return: %true if the xas currently references a node. |
|
*/ |
|
static inline bool xas_is_node(const struct xa_state *xas) |
|
{ |
|
return xas_valid(xas) && xas->xa_node; |
|
} |
|
|
|
/* True if the pointer is something other than a node */ |
|
static inline bool xas_not_node(struct xa_node *node) |
|
{ |
|
return ((unsigned long)node & 3) || !node; |
|
} |
|
|
|
/* True if the node represents RESTART or an error */ |
|
static inline bool xas_frozen(struct xa_node *node) |
|
{ |
|
return (unsigned long)node & 2; |
|
} |
|
|
|
/* True if the node represents head-of-tree, RESTART or BOUNDS */ |
|
static inline bool xas_top(struct xa_node *node) |
|
{ |
|
return node <= XAS_RESTART; |
|
} |
|
|
|
/** |
|
* xas_reset() - Reset an XArray operation state. |
|
* @xas: XArray operation state. |
|
* |
|
* Resets the error or walk state of the @xas so future walks of the |
|
* array will start from the root. Use this if you have dropped the |
|
* xarray lock and want to reuse the xa_state. |
|
* |
|
* Context: Any context. |
|
*/ |
|
static inline void xas_reset(struct xa_state *xas) |
|
{ |
|
xas->xa_node = XAS_RESTART; |
|
} |
|
|
|
/** |
|
* xas_retry() - Retry the operation if appropriate. |
|
* @xas: XArray operation state. |
|
* @entry: Entry from xarray. |
|
* |
|
* The advanced functions may sometimes return an internal entry, such as |
|
* a retry entry or a zero entry. This function sets up the @xas to restart |
|
* the walk from the head of the array if needed. |
|
* |
|
* Context: Any context. |
|
* Return: true if the operation needs to be retried. |
|
*/ |
|
static inline bool xas_retry(struct xa_state *xas, const void *entry) |
|
{ |
|
if (xa_is_zero(entry)) |
|
return true; |
|
if (!xa_is_retry(entry)) |
|
return false; |
|
xas_reset(xas); |
|
return true; |
|
} |
|
|
|
void *xas_load(struct xa_state *); |
|
void *xas_store(struct xa_state *, void *entry); |
|
void *xas_find(struct xa_state *, unsigned long max); |
|
void *xas_find_conflict(struct xa_state *); |
|
|
|
bool xas_get_mark(const struct xa_state *, xa_mark_t); |
|
void xas_set_mark(const struct xa_state *, xa_mark_t); |
|
void xas_clear_mark(const struct xa_state *, xa_mark_t); |
|
void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t); |
|
void xas_init_marks(const struct xa_state *); |
|
|
|
bool xas_nomem(struct xa_state *, gfp_t); |
|
void xas_pause(struct xa_state *); |
|
|
|
void xas_create_range(struct xa_state *); |
|
|
|
#ifdef CONFIG_XARRAY_MULTI |
|
int xa_get_order(struct xarray *, unsigned long index); |
|
void xas_split(struct xa_state *, void *entry, unsigned int order); |
|
void xas_split_alloc(struct xa_state *, void *entry, unsigned int order, gfp_t); |
|
#else |
|
static inline int xa_get_order(struct xarray *xa, unsigned long index) |
|
{ |
|
return 0; |
|
} |
|
|
|
static inline void xas_split(struct xa_state *xas, void *entry, |
|
unsigned int order) |
|
{ |
|
xas_store(xas, entry); |
|
} |
|
|
|
static inline void xas_split_alloc(struct xa_state *xas, void *entry, |
|
unsigned int order, gfp_t gfp) |
|
{ |
|
} |
|
#endif |
|
|
|
/** |
|
* xas_reload() - Refetch an entry from the xarray. |
|
* @xas: XArray operation state. |
|
* |
|
* Use this function to check that a previously loaded entry still has |
|
* the same value. This is useful for the lockless pagecache lookup where |
|
* we walk the array with only the RCU lock to protect us, lock the page, |
|
* then check that the page hasn't moved since we looked it up. |
|
* |
|
* The caller guarantees that @xas is still valid. If it may be in an |
|
* error or restart state, call xas_load() instead. |
|
* |
|
* Return: The entry at this location in the xarray. |
|
*/ |
|
static inline void *xas_reload(struct xa_state *xas) |
|
{ |
|
struct xa_node *node = xas->xa_node; |
|
void *entry; |
|
char offset; |
|
|
|
if (!node) |
|
return xa_head(xas->xa); |
|
if (IS_ENABLED(CONFIG_XARRAY_MULTI)) { |
|
offset = (xas->xa_index >> node->shift) & XA_CHUNK_MASK; |
|
entry = xa_entry(xas->xa, node, offset); |
|
if (!xa_is_sibling(entry)) |
|
return entry; |
|
offset = xa_to_sibling(entry); |
|
} else { |
|
offset = xas->xa_offset; |
|
} |
|
return xa_entry(xas->xa, node, offset); |
|
} |
|
|
|
/** |
|
* xas_set() - Set up XArray operation state for a different index. |
|
* @xas: XArray operation state. |
|
* @index: New index into the XArray. |
|
* |
|
* Move the operation state to refer to a different index. This will |
|
* have the effect of starting a walk from the top; see xas_next() |
|
* to move to an adjacent index. |
|
*/ |
|
static inline void xas_set(struct xa_state *xas, unsigned long index) |
|
{ |
|
xas->xa_index = index; |
|
xas->xa_node = XAS_RESTART; |
|
} |
|
|
|
/** |
|
* xas_set_order() - Set up XArray operation state for a multislot entry. |
|
* @xas: XArray operation state. |
|
* @index: Target of the operation. |
|
* @order: Entry occupies 2^@order indices. |
|
*/ |
|
static inline void xas_set_order(struct xa_state *xas, unsigned long index, |
|
unsigned int order) |
|
{ |
|
#ifdef CONFIG_XARRAY_MULTI |
|
xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0; |
|
xas->xa_shift = order - (order % XA_CHUNK_SHIFT); |
|
xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1; |
|
xas->xa_node = XAS_RESTART; |
|
#else |
|
BUG_ON(order > 0); |
|
xas_set(xas, index); |
|
#endif |
|
} |
|
|
|
/** |
|
* xas_set_update() - Set up XArray operation state for a callback. |
|
* @xas: XArray operation state. |
|
* @update: Function to call when updating a node. |
|
* |
|
* The XArray can notify a caller after it has updated an xa_node. |
|
* This is advanced functionality and is only needed by the page cache. |
|
*/ |
|
static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update) |
|
{ |
|
xas->xa_update = update; |
|
} |
|
|
|
/** |
|
* xas_next_entry() - Advance iterator to next present entry. |
|
* @xas: XArray operation state. |
|
* @max: Highest index to return. |
|
* |
|
* xas_next_entry() is an inline function to optimise xarray traversal for |
|
* speed. It is equivalent to calling xas_find(), and will call xas_find() |
|
* for all the hard cases. |
|
* |
|
* Return: The next present entry after the one currently referred to by @xas. |
|
*/ |
|
static inline void *xas_next_entry(struct xa_state *xas, unsigned long max) |
|
{ |
|
struct xa_node *node = xas->xa_node; |
|
void *entry; |
|
|
|
if (unlikely(xas_not_node(node) || node->shift || |
|
xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK))) |
|
return xas_find(xas, max); |
|
|
|
do { |
|
if (unlikely(xas->xa_index >= max)) |
|
return xas_find(xas, max); |
|
if (unlikely(xas->xa_offset == XA_CHUNK_MASK)) |
|
return xas_find(xas, max); |
|
entry = xa_entry(xas->xa, node, xas->xa_offset + 1); |
|
if (unlikely(xa_is_internal(entry))) |
|
return xas_find(xas, max); |
|
xas->xa_offset++; |
|
xas->xa_index++; |
|
} while (!entry); |
|
|
|
return entry; |
|
} |
|
|
|
/* Private */ |
|
static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance, |
|
xa_mark_t mark) |
|
{ |
|
unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark]; |
|
unsigned int offset = xas->xa_offset; |
|
|
|
if (advance) |
|
offset++; |
|
if (XA_CHUNK_SIZE == BITS_PER_LONG) { |
|
if (offset < XA_CHUNK_SIZE) { |
|
unsigned long data = *addr & (~0UL << offset); |
|
if (data) |
|
return __ffs(data); |
|
} |
|
return XA_CHUNK_SIZE; |
|
} |
|
|
|
return find_next_bit(addr, XA_CHUNK_SIZE, offset); |
|
} |
|
|
|
/** |
|
* xas_next_marked() - Advance iterator to next marked entry. |
|
* @xas: XArray operation state. |
|
* @max: Highest index to return. |
|
* @mark: Mark to search for. |
|
* |
|
* xas_next_marked() is an inline function to optimise xarray traversal for |
|
* speed. It is equivalent to calling xas_find_marked(), and will call |
|
* xas_find_marked() for all the hard cases. |
|
* |
|
* Return: The next marked entry after the one currently referred to by @xas. |
|
*/ |
|
static inline void *xas_next_marked(struct xa_state *xas, unsigned long max, |
|
xa_mark_t mark) |
|
{ |
|
struct xa_node *node = xas->xa_node; |
|
void *entry; |
|
unsigned int offset; |
|
|
|
if (unlikely(xas_not_node(node) || node->shift)) |
|
return xas_find_marked(xas, max, mark); |
|
offset = xas_find_chunk(xas, true, mark); |
|
xas->xa_offset = offset; |
|
xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset; |
|
if (xas->xa_index > max) |
|
return NULL; |
|
if (offset == XA_CHUNK_SIZE) |
|
return xas_find_marked(xas, max, mark); |
|
entry = xa_entry(xas->xa, node, offset); |
|
if (!entry) |
|
return xas_find_marked(xas, max, mark); |
|
return entry; |
|
} |
|
|
|
/* |
|
* If iterating while holding a lock, drop the lock and reschedule |
|
* every %XA_CHECK_SCHED loops. |
|
*/ |
|
enum { |
|
XA_CHECK_SCHED = 4096, |
|
}; |
|
|
|
/** |
|
* xas_for_each() - Iterate over a range of an XArray. |
|
* @xas: XArray operation state. |
|
* @entry: Entry retrieved from the array. |
|
* @max: Maximum index to retrieve from array. |
|
* |
|
* The loop body will be executed for each entry present in the xarray |
|
* between the current xas position and @max. @entry will be set to |
|
* the entry retrieved from the xarray. It is safe to delete entries |
|
* from the array in the loop body. You should hold either the RCU lock |
|
* or the xa_lock while iterating. If you need to drop the lock, call |
|
* xas_pause() first. |
|
*/ |
|
#define xas_for_each(xas, entry, max) \ |
|
for (entry = xas_find(xas, max); entry; \ |
|
entry = xas_next_entry(xas, max)) |
|
|
|
/** |
|
* xas_for_each_marked() - Iterate over a range of an XArray. |
|
* @xas: XArray operation state. |
|
* @entry: Entry retrieved from the array. |
|
* @max: Maximum index to retrieve from array. |
|
* @mark: Mark to search for. |
|
* |
|
* The loop body will be executed for each marked entry in the xarray |
|
* between the current xas position and @max. @entry will be set to |
|
* the entry retrieved from the xarray. It is safe to delete entries |
|
* from the array in the loop body. You should hold either the RCU lock |
|
* or the xa_lock while iterating. If you need to drop the lock, call |
|
* xas_pause() first. |
|
*/ |
|
#define xas_for_each_marked(xas, entry, max, mark) \ |
|
for (entry = xas_find_marked(xas, max, mark); entry; \ |
|
entry = xas_next_marked(xas, max, mark)) |
|
|
|
/** |
|
* xas_for_each_conflict() - Iterate over a range of an XArray. |
|
* @xas: XArray operation state. |
|
* @entry: Entry retrieved from the array. |
|
* |
|
* The loop body will be executed for each entry in the XArray that |
|
* lies within the range specified by @xas. If the loop terminates |
|
* normally, @entry will be %NULL. The user may break out of the loop, |
|
* which will leave @entry set to the conflicting entry. The caller |
|
* may also call xa_set_err() to exit the loop while setting an error |
|
* to record the reason. |
|
*/ |
|
#define xas_for_each_conflict(xas, entry) \ |
|
while ((entry = xas_find_conflict(xas))) |
|
|
|
void *__xas_next(struct xa_state *); |
|
void *__xas_prev(struct xa_state *); |
|
|
|
/** |
|
* xas_prev() - Move iterator to previous index. |
|
* @xas: XArray operation state. |
|
* |
|
* If the @xas was in an error state, it will remain in an error state |
|
* and this function will return %NULL. If the @xas has never been walked, |
|
* it will have the effect of calling xas_load(). Otherwise one will be |
|
* subtracted from the index and the state will be walked to the correct |
|
* location in the array for the next operation. |
|
* |
|
* If the iterator was referencing index 0, this function wraps |
|
* around to %ULONG_MAX. |
|
* |
|
* Return: The entry at the new index. This may be %NULL or an internal |
|
* entry. |
|
*/ |
|
static inline void *xas_prev(struct xa_state *xas) |
|
{ |
|
struct xa_node *node = xas->xa_node; |
|
|
|
if (unlikely(xas_not_node(node) || node->shift || |
|
xas->xa_offset == 0)) |
|
return __xas_prev(xas); |
|
|
|
xas->xa_index--; |
|
xas->xa_offset--; |
|
return xa_entry(xas->xa, node, xas->xa_offset); |
|
} |
|
|
|
/** |
|
* xas_next() - Move state to next index. |
|
* @xas: XArray operation state. |
|
* |
|
* If the @xas was in an error state, it will remain in an error state |
|
* and this function will return %NULL. If the @xas has never been walked, |
|
* it will have the effect of calling xas_load(). Otherwise one will be |
|
* added to the index and the state will be walked to the correct |
|
* location in the array for the next operation. |
|
* |
|
* If the iterator was referencing index %ULONG_MAX, this function wraps |
|
* around to 0. |
|
* |
|
* Return: The entry at the new index. This may be %NULL or an internal |
|
* entry. |
|
*/ |
|
static inline void *xas_next(struct xa_state *xas) |
|
{ |
|
struct xa_node *node = xas->xa_node; |
|
|
|
if (unlikely(xas_not_node(node) || node->shift || |
|
xas->xa_offset == XA_CHUNK_MASK)) |
|
return __xas_next(xas); |
|
|
|
xas->xa_index++; |
|
xas->xa_offset++; |
|
return xa_entry(xas->xa, node, xas->xa_offset); |
|
} |
|
|
|
#endif /* _LINUX_XARRAY_H */
|
|
|