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1249 lines
30 KiB
1249 lines
30 KiB
/* |
|
* Public API and common code for kernel->userspace relay file support. |
|
* |
|
* See Documentation/filesystems/relay.rst for an overview. |
|
* |
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* Copyright (C) 2002-2005 - Tom Zanussi ([email protected]), IBM Corp |
|
* Copyright (C) 1999-2005 - Karim Yaghmour ([email protected]) |
|
* |
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* Moved to kernel/relay.c by Paul Mundt, 2006. |
|
* November 2006 - CPU hotplug support by Mathieu Desnoyers |
|
* ([email protected]) |
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* |
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* This file is released under the GPL. |
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*/ |
|
#include <linux/errno.h> |
|
#include <linux/stddef.h> |
|
#include <linux/slab.h> |
|
#include <linux/export.h> |
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#include <linux/string.h> |
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#include <linux/relay.h> |
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#include <linux/vmalloc.h> |
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#include <linux/mm.h> |
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#include <linux/cpu.h> |
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#include <linux/splice.h> |
|
|
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/* list of open channels, for cpu hotplug */ |
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static DEFINE_MUTEX(relay_channels_mutex); |
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static LIST_HEAD(relay_channels); |
|
|
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/* |
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* fault() vm_op implementation for relay file mapping. |
|
*/ |
|
static vm_fault_t relay_buf_fault(struct vm_fault *vmf) |
|
{ |
|
struct page *page; |
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struct rchan_buf *buf = vmf->vma->vm_private_data; |
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pgoff_t pgoff = vmf->pgoff; |
|
|
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if (!buf) |
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return VM_FAULT_OOM; |
|
|
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page = vmalloc_to_page(buf->start + (pgoff << PAGE_SHIFT)); |
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if (!page) |
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return VM_FAULT_SIGBUS; |
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get_page(page); |
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vmf->page = page; |
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|
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return 0; |
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} |
|
|
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/* |
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* vm_ops for relay file mappings. |
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*/ |
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static const struct vm_operations_struct relay_file_mmap_ops = { |
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.fault = relay_buf_fault, |
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}; |
|
|
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/* |
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* allocate an array of pointers of struct page |
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*/ |
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static struct page **relay_alloc_page_array(unsigned int n_pages) |
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{ |
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const size_t pa_size = n_pages * sizeof(struct page *); |
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if (pa_size > PAGE_SIZE) |
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return vzalloc(pa_size); |
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return kzalloc(pa_size, GFP_KERNEL); |
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} |
|
|
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/* |
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* free an array of pointers of struct page |
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*/ |
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static void relay_free_page_array(struct page **array) |
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{ |
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kvfree(array); |
|
} |
|
|
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/** |
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* relay_mmap_buf: - mmap channel buffer to process address space |
|
* @buf: relay channel buffer |
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* @vma: vm_area_struct describing memory to be mapped |
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* |
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* Returns 0 if ok, negative on error |
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* |
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* Caller should already have grabbed mmap_lock. |
|
*/ |
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static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) |
|
{ |
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unsigned long length = vma->vm_end - vma->vm_start; |
|
|
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if (!buf) |
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return -EBADF; |
|
|
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if (length != (unsigned long)buf->chan->alloc_size) |
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return -EINVAL; |
|
|
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vma->vm_ops = &relay_file_mmap_ops; |
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vma->vm_flags |= VM_DONTEXPAND; |
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vma->vm_private_data = buf; |
|
|
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return 0; |
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} |
|
|
|
/** |
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* relay_alloc_buf - allocate a channel buffer |
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* @buf: the buffer struct |
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* @size: total size of the buffer |
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* |
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* Returns a pointer to the resulting buffer, %NULL if unsuccessful. The |
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* passed in size will get page aligned, if it isn't already. |
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*/ |
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static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size) |
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{ |
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void *mem; |
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unsigned int i, j, n_pages; |
|
|
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*size = PAGE_ALIGN(*size); |
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n_pages = *size >> PAGE_SHIFT; |
|
|
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buf->page_array = relay_alloc_page_array(n_pages); |
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if (!buf->page_array) |
|
return NULL; |
|
|
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for (i = 0; i < n_pages; i++) { |
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buf->page_array[i] = alloc_page(GFP_KERNEL); |
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if (unlikely(!buf->page_array[i])) |
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goto depopulate; |
|
set_page_private(buf->page_array[i], (unsigned long)buf); |
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} |
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mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); |
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if (!mem) |
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goto depopulate; |
|
|
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memset(mem, 0, *size); |
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buf->page_count = n_pages; |
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return mem; |
|
|
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depopulate: |
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for (j = 0; j < i; j++) |
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__free_page(buf->page_array[j]); |
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relay_free_page_array(buf->page_array); |
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return NULL; |
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} |
|
|
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/** |
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* relay_create_buf - allocate and initialize a channel buffer |
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* @chan: the relay channel |
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* |
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* Returns channel buffer if successful, %NULL otherwise. |
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*/ |
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static struct rchan_buf *relay_create_buf(struct rchan *chan) |
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{ |
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struct rchan_buf *buf; |
|
|
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if (chan->n_subbufs > KMALLOC_MAX_SIZE / sizeof(size_t *)) |
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return NULL; |
|
|
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buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL); |
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if (!buf) |
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return NULL; |
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buf->padding = kmalloc_array(chan->n_subbufs, sizeof(size_t *), |
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GFP_KERNEL); |
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if (!buf->padding) |
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goto free_buf; |
|
|
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buf->start = relay_alloc_buf(buf, &chan->alloc_size); |
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if (!buf->start) |
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goto free_buf; |
|
|
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buf->chan = chan; |
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kref_get(&buf->chan->kref); |
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return buf; |
|
|
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free_buf: |
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kfree(buf->padding); |
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kfree(buf); |
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return NULL; |
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} |
|
|
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/** |
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* relay_destroy_channel - free the channel struct |
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* @kref: target kernel reference that contains the relay channel |
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* |
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* Should only be called from kref_put(). |
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*/ |
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static void relay_destroy_channel(struct kref *kref) |
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{ |
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struct rchan *chan = container_of(kref, struct rchan, kref); |
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free_percpu(chan->buf); |
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kfree(chan); |
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} |
|
|
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/** |
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* relay_destroy_buf - destroy an rchan_buf struct and associated buffer |
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* @buf: the buffer struct |
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*/ |
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static void relay_destroy_buf(struct rchan_buf *buf) |
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{ |
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struct rchan *chan = buf->chan; |
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unsigned int i; |
|
|
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if (likely(buf->start)) { |
|
vunmap(buf->start); |
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for (i = 0; i < buf->page_count; i++) |
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__free_page(buf->page_array[i]); |
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relay_free_page_array(buf->page_array); |
|
} |
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*per_cpu_ptr(chan->buf, buf->cpu) = NULL; |
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kfree(buf->padding); |
|
kfree(buf); |
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kref_put(&chan->kref, relay_destroy_channel); |
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} |
|
|
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/** |
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* relay_remove_buf - remove a channel buffer |
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* @kref: target kernel reference that contains the relay buffer |
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* |
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* Removes the file from the filesystem, which also frees the |
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* rchan_buf_struct and the channel buffer. Should only be called from |
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* kref_put(). |
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*/ |
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static void relay_remove_buf(struct kref *kref) |
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{ |
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struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); |
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relay_destroy_buf(buf); |
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} |
|
|
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/** |
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* relay_buf_empty - boolean, is the channel buffer empty? |
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* @buf: channel buffer |
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* |
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* Returns 1 if the buffer is empty, 0 otherwise. |
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*/ |
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static int relay_buf_empty(struct rchan_buf *buf) |
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{ |
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return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; |
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} |
|
|
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/** |
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* relay_buf_full - boolean, is the channel buffer full? |
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* @buf: channel buffer |
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* |
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* Returns 1 if the buffer is full, 0 otherwise. |
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*/ |
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int relay_buf_full(struct rchan_buf *buf) |
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{ |
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size_t ready = buf->subbufs_produced - buf->subbufs_consumed; |
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return (ready >= buf->chan->n_subbufs) ? 1 : 0; |
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} |
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EXPORT_SYMBOL_GPL(relay_buf_full); |
|
|
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/* |
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* High-level relay kernel API and associated functions. |
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*/ |
|
|
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static int relay_subbuf_start(struct rchan_buf *buf, void *subbuf, |
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void *prev_subbuf, size_t prev_padding) |
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{ |
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if (!buf->chan->cb->subbuf_start) |
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return !relay_buf_full(buf); |
|
|
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return buf->chan->cb->subbuf_start(buf, subbuf, |
|
prev_subbuf, prev_padding); |
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} |
|
|
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/** |
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* wakeup_readers - wake up readers waiting on a channel |
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* @work: contains the channel buffer |
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* |
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* This is the function used to defer reader waking |
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*/ |
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static void wakeup_readers(struct irq_work *work) |
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{ |
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struct rchan_buf *buf; |
|
|
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buf = container_of(work, struct rchan_buf, wakeup_work); |
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wake_up_interruptible(&buf->read_wait); |
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} |
|
|
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/** |
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* __relay_reset - reset a channel buffer |
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* @buf: the channel buffer |
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* @init: 1 if this is a first-time initialization |
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* |
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* See relay_reset() for description of effect. |
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*/ |
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static void __relay_reset(struct rchan_buf *buf, unsigned int init) |
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{ |
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size_t i; |
|
|
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if (init) { |
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init_waitqueue_head(&buf->read_wait); |
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kref_init(&buf->kref); |
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init_irq_work(&buf->wakeup_work, wakeup_readers); |
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} else { |
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irq_work_sync(&buf->wakeup_work); |
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} |
|
|
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buf->subbufs_produced = 0; |
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buf->subbufs_consumed = 0; |
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buf->bytes_consumed = 0; |
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buf->finalized = 0; |
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buf->data = buf->start; |
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buf->offset = 0; |
|
|
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for (i = 0; i < buf->chan->n_subbufs; i++) |
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buf->padding[i] = 0; |
|
|
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relay_subbuf_start(buf, buf->data, NULL, 0); |
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} |
|
|
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/** |
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* relay_reset - reset the channel |
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* @chan: the channel |
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* |
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* This has the effect of erasing all data from all channel buffers |
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* and restarting the channel in its initial state. The buffers |
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* are not freed, so any mappings are still in effect. |
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* |
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* NOTE. Care should be taken that the channel isn't actually |
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* being used by anything when this call is made. |
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*/ |
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void relay_reset(struct rchan *chan) |
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{ |
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struct rchan_buf *buf; |
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unsigned int i; |
|
|
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if (!chan) |
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return; |
|
|
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if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) { |
|
__relay_reset(buf, 0); |
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return; |
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} |
|
|
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mutex_lock(&relay_channels_mutex); |
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for_each_possible_cpu(i) |
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if ((buf = *per_cpu_ptr(chan->buf, i))) |
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__relay_reset(buf, 0); |
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mutex_unlock(&relay_channels_mutex); |
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} |
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EXPORT_SYMBOL_GPL(relay_reset); |
|
|
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static inline void relay_set_buf_dentry(struct rchan_buf *buf, |
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struct dentry *dentry) |
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{ |
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buf->dentry = dentry; |
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d_inode(buf->dentry)->i_size = buf->early_bytes; |
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} |
|
|
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static struct dentry *relay_create_buf_file(struct rchan *chan, |
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struct rchan_buf *buf, |
|
unsigned int cpu) |
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{ |
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struct dentry *dentry; |
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char *tmpname; |
|
|
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tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); |
|
if (!tmpname) |
|
return NULL; |
|
snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu); |
|
|
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/* Create file in fs */ |
|
dentry = chan->cb->create_buf_file(tmpname, chan->parent, |
|
S_IRUSR, buf, |
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&chan->is_global); |
|
if (IS_ERR(dentry)) |
|
dentry = NULL; |
|
|
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kfree(tmpname); |
|
|
|
return dentry; |
|
} |
|
|
|
/* |
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* relay_open_buf - create a new relay channel buffer |
|
* |
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* used by relay_open() and CPU hotplug. |
|
*/ |
|
static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu) |
|
{ |
|
struct rchan_buf *buf = NULL; |
|
struct dentry *dentry; |
|
|
|
if (chan->is_global) |
|
return *per_cpu_ptr(chan->buf, 0); |
|
|
|
buf = relay_create_buf(chan); |
|
if (!buf) |
|
return NULL; |
|
|
|
if (chan->has_base_filename) { |
|
dentry = relay_create_buf_file(chan, buf, cpu); |
|
if (!dentry) |
|
goto free_buf; |
|
relay_set_buf_dentry(buf, dentry); |
|
} else { |
|
/* Only retrieve global info, nothing more, nothing less */ |
|
dentry = chan->cb->create_buf_file(NULL, NULL, |
|
S_IRUSR, buf, |
|
&chan->is_global); |
|
if (IS_ERR_OR_NULL(dentry)) |
|
goto free_buf; |
|
} |
|
|
|
buf->cpu = cpu; |
|
__relay_reset(buf, 1); |
|
|
|
if(chan->is_global) { |
|
*per_cpu_ptr(chan->buf, 0) = buf; |
|
buf->cpu = 0; |
|
} |
|
|
|
return buf; |
|
|
|
free_buf: |
|
relay_destroy_buf(buf); |
|
return NULL; |
|
} |
|
|
|
/** |
|
* relay_close_buf - close a channel buffer |
|
* @buf: channel buffer |
|
* |
|
* Marks the buffer finalized and restores the default callbacks. |
|
* The channel buffer and channel buffer data structure are then freed |
|
* automatically when the last reference is given up. |
|
*/ |
|
static void relay_close_buf(struct rchan_buf *buf) |
|
{ |
|
buf->finalized = 1; |
|
irq_work_sync(&buf->wakeup_work); |
|
buf->chan->cb->remove_buf_file(buf->dentry); |
|
kref_put(&buf->kref, relay_remove_buf); |
|
} |
|
|
|
int relay_prepare_cpu(unsigned int cpu) |
|
{ |
|
struct rchan *chan; |
|
struct rchan_buf *buf; |
|
|
|
mutex_lock(&relay_channels_mutex); |
|
list_for_each_entry(chan, &relay_channels, list) { |
|
if ((buf = *per_cpu_ptr(chan->buf, cpu))) |
|
continue; |
|
buf = relay_open_buf(chan, cpu); |
|
if (!buf) { |
|
pr_err("relay: cpu %d buffer creation failed\n", cpu); |
|
mutex_unlock(&relay_channels_mutex); |
|
return -ENOMEM; |
|
} |
|
*per_cpu_ptr(chan->buf, cpu) = buf; |
|
} |
|
mutex_unlock(&relay_channels_mutex); |
|
return 0; |
|
} |
|
|
|
/** |
|
* relay_open - create a new relay channel |
|
* @base_filename: base name of files to create, %NULL for buffering only |
|
* @parent: dentry of parent directory, %NULL for root directory or buffer |
|
* @subbuf_size: size of sub-buffers |
|
* @n_subbufs: number of sub-buffers |
|
* @cb: client callback functions |
|
* @private_data: user-defined data |
|
* |
|
* Returns channel pointer if successful, %NULL otherwise. |
|
* |
|
* Creates a channel buffer for each cpu using the sizes and |
|
* attributes specified. The created channel buffer files |
|
* will be named base_filename0...base_filenameN-1. File |
|
* permissions will be %S_IRUSR. |
|
* |
|
* If opening a buffer (@parent = NULL) that you later wish to register |
|
* in a filesystem, call relay_late_setup_files() once the @parent dentry |
|
* is available. |
|
*/ |
|
struct rchan *relay_open(const char *base_filename, |
|
struct dentry *parent, |
|
size_t subbuf_size, |
|
size_t n_subbufs, |
|
const struct rchan_callbacks *cb, |
|
void *private_data) |
|
{ |
|
unsigned int i; |
|
struct rchan *chan; |
|
struct rchan_buf *buf; |
|
|
|
if (!(subbuf_size && n_subbufs)) |
|
return NULL; |
|
if (subbuf_size > UINT_MAX / n_subbufs) |
|
return NULL; |
|
if (!cb || !cb->create_buf_file || !cb->remove_buf_file) |
|
return NULL; |
|
|
|
chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); |
|
if (!chan) |
|
return NULL; |
|
|
|
chan->buf = alloc_percpu(struct rchan_buf *); |
|
if (!chan->buf) { |
|
kfree(chan); |
|
return NULL; |
|
} |
|
|
|
chan->version = RELAYFS_CHANNEL_VERSION; |
|
chan->n_subbufs = n_subbufs; |
|
chan->subbuf_size = subbuf_size; |
|
chan->alloc_size = PAGE_ALIGN(subbuf_size * n_subbufs); |
|
chan->parent = parent; |
|
chan->private_data = private_data; |
|
if (base_filename) { |
|
chan->has_base_filename = 1; |
|
strlcpy(chan->base_filename, base_filename, NAME_MAX); |
|
} |
|
chan->cb = cb; |
|
kref_init(&chan->kref); |
|
|
|
mutex_lock(&relay_channels_mutex); |
|
for_each_online_cpu(i) { |
|
buf = relay_open_buf(chan, i); |
|
if (!buf) |
|
goto free_bufs; |
|
*per_cpu_ptr(chan->buf, i) = buf; |
|
} |
|
list_add(&chan->list, &relay_channels); |
|
mutex_unlock(&relay_channels_mutex); |
|
|
|
return chan; |
|
|
|
free_bufs: |
|
for_each_possible_cpu(i) { |
|
if ((buf = *per_cpu_ptr(chan->buf, i))) |
|
relay_close_buf(buf); |
|
} |
|
|
|
kref_put(&chan->kref, relay_destroy_channel); |
|
mutex_unlock(&relay_channels_mutex); |
|
return NULL; |
|
} |
|
EXPORT_SYMBOL_GPL(relay_open); |
|
|
|
struct rchan_percpu_buf_dispatcher { |
|
struct rchan_buf *buf; |
|
struct dentry *dentry; |
|
}; |
|
|
|
/* Called in atomic context. */ |
|
static void __relay_set_buf_dentry(void *info) |
|
{ |
|
struct rchan_percpu_buf_dispatcher *p = info; |
|
|
|
relay_set_buf_dentry(p->buf, p->dentry); |
|
} |
|
|
|
/** |
|
* relay_late_setup_files - triggers file creation |
|
* @chan: channel to operate on |
|
* @base_filename: base name of files to create |
|
* @parent: dentry of parent directory, %NULL for root directory |
|
* |
|
* Returns 0 if successful, non-zero otherwise. |
|
* |
|
* Use to setup files for a previously buffer-only channel created |
|
* by relay_open() with a NULL parent dentry. |
|
* |
|
* For example, this is useful for perfomring early tracing in kernel, |
|
* before VFS is up and then exposing the early results once the dentry |
|
* is available. |
|
*/ |
|
int relay_late_setup_files(struct rchan *chan, |
|
const char *base_filename, |
|
struct dentry *parent) |
|
{ |
|
int err = 0; |
|
unsigned int i, curr_cpu; |
|
unsigned long flags; |
|
struct dentry *dentry; |
|
struct rchan_buf *buf; |
|
struct rchan_percpu_buf_dispatcher disp; |
|
|
|
if (!chan || !base_filename) |
|
return -EINVAL; |
|
|
|
strlcpy(chan->base_filename, base_filename, NAME_MAX); |
|
|
|
mutex_lock(&relay_channels_mutex); |
|
/* Is chan already set up? */ |
|
if (unlikely(chan->has_base_filename)) { |
|
mutex_unlock(&relay_channels_mutex); |
|
return -EEXIST; |
|
} |
|
chan->has_base_filename = 1; |
|
chan->parent = parent; |
|
|
|
if (chan->is_global) { |
|
err = -EINVAL; |
|
buf = *per_cpu_ptr(chan->buf, 0); |
|
if (!WARN_ON_ONCE(!buf)) { |
|
dentry = relay_create_buf_file(chan, buf, 0); |
|
if (dentry && !WARN_ON_ONCE(!chan->is_global)) { |
|
relay_set_buf_dentry(buf, dentry); |
|
err = 0; |
|
} |
|
} |
|
mutex_unlock(&relay_channels_mutex); |
|
return err; |
|
} |
|
|
|
curr_cpu = get_cpu(); |
|
/* |
|
* The CPU hotplug notifier ran before us and created buffers with |
|
* no files associated. So it's safe to call relay_setup_buf_file() |
|
* on all currently online CPUs. |
|
*/ |
|
for_each_online_cpu(i) { |
|
buf = *per_cpu_ptr(chan->buf, i); |
|
if (unlikely(!buf)) { |
|
WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n"); |
|
err = -EINVAL; |
|
break; |
|
} |
|
|
|
dentry = relay_create_buf_file(chan, buf, i); |
|
if (unlikely(!dentry)) { |
|
err = -EINVAL; |
|
break; |
|
} |
|
|
|
if (curr_cpu == i) { |
|
local_irq_save(flags); |
|
relay_set_buf_dentry(buf, dentry); |
|
local_irq_restore(flags); |
|
} else { |
|
disp.buf = buf; |
|
disp.dentry = dentry; |
|
smp_mb(); |
|
/* relay_channels_mutex must be held, so wait. */ |
|
err = smp_call_function_single(i, |
|
__relay_set_buf_dentry, |
|
&disp, 1); |
|
} |
|
if (unlikely(err)) |
|
break; |
|
} |
|
put_cpu(); |
|
mutex_unlock(&relay_channels_mutex); |
|
|
|
return err; |
|
} |
|
EXPORT_SYMBOL_GPL(relay_late_setup_files); |
|
|
|
/** |
|
* relay_switch_subbuf - switch to a new sub-buffer |
|
* @buf: channel buffer |
|
* @length: size of current event |
|
* |
|
* Returns either the length passed in or 0 if full. |
|
* |
|
* Performs sub-buffer-switch tasks such as invoking callbacks, |
|
* updating padding counts, waking up readers, etc. |
|
*/ |
|
size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) |
|
{ |
|
void *old, *new; |
|
size_t old_subbuf, new_subbuf; |
|
|
|
if (unlikely(length > buf->chan->subbuf_size)) |
|
goto toobig; |
|
|
|
if (buf->offset != buf->chan->subbuf_size + 1) { |
|
buf->prev_padding = buf->chan->subbuf_size - buf->offset; |
|
old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; |
|
buf->padding[old_subbuf] = buf->prev_padding; |
|
buf->subbufs_produced++; |
|
if (buf->dentry) |
|
d_inode(buf->dentry)->i_size += |
|
buf->chan->subbuf_size - |
|
buf->padding[old_subbuf]; |
|
else |
|
buf->early_bytes += buf->chan->subbuf_size - |
|
buf->padding[old_subbuf]; |
|
smp_mb(); |
|
if (waitqueue_active(&buf->read_wait)) { |
|
/* |
|
* Calling wake_up_interruptible() from here |
|
* will deadlock if we happen to be logging |
|
* from the scheduler (trying to re-grab |
|
* rq->lock), so defer it. |
|
*/ |
|
irq_work_queue(&buf->wakeup_work); |
|
} |
|
} |
|
|
|
old = buf->data; |
|
new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; |
|
new = buf->start + new_subbuf * buf->chan->subbuf_size; |
|
buf->offset = 0; |
|
if (!relay_subbuf_start(buf, new, old, buf->prev_padding)) { |
|
buf->offset = buf->chan->subbuf_size + 1; |
|
return 0; |
|
} |
|
buf->data = new; |
|
buf->padding[new_subbuf] = 0; |
|
|
|
if (unlikely(length + buf->offset > buf->chan->subbuf_size)) |
|
goto toobig; |
|
|
|
return length; |
|
|
|
toobig: |
|
buf->chan->last_toobig = length; |
|
return 0; |
|
} |
|
EXPORT_SYMBOL_GPL(relay_switch_subbuf); |
|
|
|
/** |
|
* relay_subbufs_consumed - update the buffer's sub-buffers-consumed count |
|
* @chan: the channel |
|
* @cpu: the cpu associated with the channel buffer to update |
|
* @subbufs_consumed: number of sub-buffers to add to current buf's count |
|
* |
|
* Adds to the channel buffer's consumed sub-buffer count. |
|
* subbufs_consumed should be the number of sub-buffers newly consumed, |
|
* not the total consumed. |
|
* |
|
* NOTE. Kernel clients don't need to call this function if the channel |
|
* mode is 'overwrite'. |
|
*/ |
|
void relay_subbufs_consumed(struct rchan *chan, |
|
unsigned int cpu, |
|
size_t subbufs_consumed) |
|
{ |
|
struct rchan_buf *buf; |
|
|
|
if (!chan || cpu >= NR_CPUS) |
|
return; |
|
|
|
buf = *per_cpu_ptr(chan->buf, cpu); |
|
if (!buf || subbufs_consumed > chan->n_subbufs) |
|
return; |
|
|
|
if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed) |
|
buf->subbufs_consumed = buf->subbufs_produced; |
|
else |
|
buf->subbufs_consumed += subbufs_consumed; |
|
} |
|
EXPORT_SYMBOL_GPL(relay_subbufs_consumed); |
|
|
|
/** |
|
* relay_close - close the channel |
|
* @chan: the channel |
|
* |
|
* Closes all channel buffers and frees the channel. |
|
*/ |
|
void relay_close(struct rchan *chan) |
|
{ |
|
struct rchan_buf *buf; |
|
unsigned int i; |
|
|
|
if (!chan) |
|
return; |
|
|
|
mutex_lock(&relay_channels_mutex); |
|
if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) |
|
relay_close_buf(buf); |
|
else |
|
for_each_possible_cpu(i) |
|
if ((buf = *per_cpu_ptr(chan->buf, i))) |
|
relay_close_buf(buf); |
|
|
|
if (chan->last_toobig) |
|
printk(KERN_WARNING "relay: one or more items not logged " |
|
"[item size (%zd) > sub-buffer size (%zd)]\n", |
|
chan->last_toobig, chan->subbuf_size); |
|
|
|
list_del(&chan->list); |
|
kref_put(&chan->kref, relay_destroy_channel); |
|
mutex_unlock(&relay_channels_mutex); |
|
} |
|
EXPORT_SYMBOL_GPL(relay_close); |
|
|
|
/** |
|
* relay_flush - close the channel |
|
* @chan: the channel |
|
* |
|
* Flushes all channel buffers, i.e. forces buffer switch. |
|
*/ |
|
void relay_flush(struct rchan *chan) |
|
{ |
|
struct rchan_buf *buf; |
|
unsigned int i; |
|
|
|
if (!chan) |
|
return; |
|
|
|
if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) { |
|
relay_switch_subbuf(buf, 0); |
|
return; |
|
} |
|
|
|
mutex_lock(&relay_channels_mutex); |
|
for_each_possible_cpu(i) |
|
if ((buf = *per_cpu_ptr(chan->buf, i))) |
|
relay_switch_subbuf(buf, 0); |
|
mutex_unlock(&relay_channels_mutex); |
|
} |
|
EXPORT_SYMBOL_GPL(relay_flush); |
|
|
|
/** |
|
* relay_file_open - open file op for relay files |
|
* @inode: the inode |
|
* @filp: the file |
|
* |
|
* Increments the channel buffer refcount. |
|
*/ |
|
static int relay_file_open(struct inode *inode, struct file *filp) |
|
{ |
|
struct rchan_buf *buf = inode->i_private; |
|
kref_get(&buf->kref); |
|
filp->private_data = buf; |
|
|
|
return nonseekable_open(inode, filp); |
|
} |
|
|
|
/** |
|
* relay_file_mmap - mmap file op for relay files |
|
* @filp: the file |
|
* @vma: the vma describing what to map |
|
* |
|
* Calls upon relay_mmap_buf() to map the file into user space. |
|
*/ |
|
static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) |
|
{ |
|
struct rchan_buf *buf = filp->private_data; |
|
return relay_mmap_buf(buf, vma); |
|
} |
|
|
|
/** |
|
* relay_file_poll - poll file op for relay files |
|
* @filp: the file |
|
* @wait: poll table |
|
* |
|
* Poll implemention. |
|
*/ |
|
static __poll_t relay_file_poll(struct file *filp, poll_table *wait) |
|
{ |
|
__poll_t mask = 0; |
|
struct rchan_buf *buf = filp->private_data; |
|
|
|
if (buf->finalized) |
|
return EPOLLERR; |
|
|
|
if (filp->f_mode & FMODE_READ) { |
|
poll_wait(filp, &buf->read_wait, wait); |
|
if (!relay_buf_empty(buf)) |
|
mask |= EPOLLIN | EPOLLRDNORM; |
|
} |
|
|
|
return mask; |
|
} |
|
|
|
/** |
|
* relay_file_release - release file op for relay files |
|
* @inode: the inode |
|
* @filp: the file |
|
* |
|
* Decrements the channel refcount, as the filesystem is |
|
* no longer using it. |
|
*/ |
|
static int relay_file_release(struct inode *inode, struct file *filp) |
|
{ |
|
struct rchan_buf *buf = filp->private_data; |
|
kref_put(&buf->kref, relay_remove_buf); |
|
|
|
return 0; |
|
} |
|
|
|
/* |
|
* relay_file_read_consume - update the consumed count for the buffer |
|
*/ |
|
static void relay_file_read_consume(struct rchan_buf *buf, |
|
size_t read_pos, |
|
size_t bytes_consumed) |
|
{ |
|
size_t subbuf_size = buf->chan->subbuf_size; |
|
size_t n_subbufs = buf->chan->n_subbufs; |
|
size_t read_subbuf; |
|
|
|
if (buf->subbufs_produced == buf->subbufs_consumed && |
|
buf->offset == buf->bytes_consumed) |
|
return; |
|
|
|
if (buf->bytes_consumed + bytes_consumed > subbuf_size) { |
|
relay_subbufs_consumed(buf->chan, buf->cpu, 1); |
|
buf->bytes_consumed = 0; |
|
} |
|
|
|
buf->bytes_consumed += bytes_consumed; |
|
if (!read_pos) |
|
read_subbuf = buf->subbufs_consumed % n_subbufs; |
|
else |
|
read_subbuf = read_pos / buf->chan->subbuf_size; |
|
if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { |
|
if ((read_subbuf == buf->subbufs_produced % n_subbufs) && |
|
(buf->offset == subbuf_size)) |
|
return; |
|
relay_subbufs_consumed(buf->chan, buf->cpu, 1); |
|
buf->bytes_consumed = 0; |
|
} |
|
} |
|
|
|
/* |
|
* relay_file_read_avail - boolean, are there unconsumed bytes available? |
|
*/ |
|
static int relay_file_read_avail(struct rchan_buf *buf) |
|
{ |
|
size_t subbuf_size = buf->chan->subbuf_size; |
|
size_t n_subbufs = buf->chan->n_subbufs; |
|
size_t produced = buf->subbufs_produced; |
|
size_t consumed; |
|
|
|
relay_file_read_consume(buf, 0, 0); |
|
|
|
consumed = buf->subbufs_consumed; |
|
|
|
if (unlikely(buf->offset > subbuf_size)) { |
|
if (produced == consumed) |
|
return 0; |
|
return 1; |
|
} |
|
|
|
if (unlikely(produced - consumed >= n_subbufs)) { |
|
consumed = produced - n_subbufs + 1; |
|
buf->subbufs_consumed = consumed; |
|
buf->bytes_consumed = 0; |
|
} |
|
|
|
produced = (produced % n_subbufs) * subbuf_size + buf->offset; |
|
consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed; |
|
|
|
if (consumed > produced) |
|
produced += n_subbufs * subbuf_size; |
|
|
|
if (consumed == produced) { |
|
if (buf->offset == subbuf_size && |
|
buf->subbufs_produced > buf->subbufs_consumed) |
|
return 1; |
|
return 0; |
|
} |
|
|
|
return 1; |
|
} |
|
|
|
/** |
|
* relay_file_read_subbuf_avail - return bytes available in sub-buffer |
|
* @read_pos: file read position |
|
* @buf: relay channel buffer |
|
*/ |
|
static size_t relay_file_read_subbuf_avail(size_t read_pos, |
|
struct rchan_buf *buf) |
|
{ |
|
size_t padding, avail = 0; |
|
size_t read_subbuf, read_offset, write_subbuf, write_offset; |
|
size_t subbuf_size = buf->chan->subbuf_size; |
|
|
|
write_subbuf = (buf->data - buf->start) / subbuf_size; |
|
write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; |
|
read_subbuf = read_pos / subbuf_size; |
|
read_offset = read_pos % subbuf_size; |
|
padding = buf->padding[read_subbuf]; |
|
|
|
if (read_subbuf == write_subbuf) { |
|
if (read_offset + padding < write_offset) |
|
avail = write_offset - (read_offset + padding); |
|
} else |
|
avail = (subbuf_size - padding) - read_offset; |
|
|
|
return avail; |
|
} |
|
|
|
/** |
|
* relay_file_read_start_pos - find the first available byte to read |
|
* @buf: relay channel buffer |
|
* |
|
* If the read_pos is in the middle of padding, return the |
|
* position of the first actually available byte, otherwise |
|
* return the original value. |
|
*/ |
|
static size_t relay_file_read_start_pos(struct rchan_buf *buf) |
|
{ |
|
size_t read_subbuf, padding, padding_start, padding_end; |
|
size_t subbuf_size = buf->chan->subbuf_size; |
|
size_t n_subbufs = buf->chan->n_subbufs; |
|
size_t consumed = buf->subbufs_consumed % n_subbufs; |
|
size_t read_pos = consumed * subbuf_size + buf->bytes_consumed; |
|
|
|
read_subbuf = read_pos / subbuf_size; |
|
padding = buf->padding[read_subbuf]; |
|
padding_start = (read_subbuf + 1) * subbuf_size - padding; |
|
padding_end = (read_subbuf + 1) * subbuf_size; |
|
if (read_pos >= padding_start && read_pos < padding_end) { |
|
read_subbuf = (read_subbuf + 1) % n_subbufs; |
|
read_pos = read_subbuf * subbuf_size; |
|
} |
|
|
|
return read_pos; |
|
} |
|
|
|
/** |
|
* relay_file_read_end_pos - return the new read position |
|
* @read_pos: file read position |
|
* @buf: relay channel buffer |
|
* @count: number of bytes to be read |
|
*/ |
|
static size_t relay_file_read_end_pos(struct rchan_buf *buf, |
|
size_t read_pos, |
|
size_t count) |
|
{ |
|
size_t read_subbuf, padding, end_pos; |
|
size_t subbuf_size = buf->chan->subbuf_size; |
|
size_t n_subbufs = buf->chan->n_subbufs; |
|
|
|
read_subbuf = read_pos / subbuf_size; |
|
padding = buf->padding[read_subbuf]; |
|
if (read_pos % subbuf_size + count + padding == subbuf_size) |
|
end_pos = (read_subbuf + 1) * subbuf_size; |
|
else |
|
end_pos = read_pos + count; |
|
if (end_pos >= subbuf_size * n_subbufs) |
|
end_pos = 0; |
|
|
|
return end_pos; |
|
} |
|
|
|
static ssize_t relay_file_read(struct file *filp, |
|
char __user *buffer, |
|
size_t count, |
|
loff_t *ppos) |
|
{ |
|
struct rchan_buf *buf = filp->private_data; |
|
size_t read_start, avail; |
|
size_t written = 0; |
|
int ret; |
|
|
|
if (!count) |
|
return 0; |
|
|
|
inode_lock(file_inode(filp)); |
|
do { |
|
void *from; |
|
|
|
if (!relay_file_read_avail(buf)) |
|
break; |
|
|
|
read_start = relay_file_read_start_pos(buf); |
|
avail = relay_file_read_subbuf_avail(read_start, buf); |
|
if (!avail) |
|
break; |
|
|
|
avail = min(count, avail); |
|
from = buf->start + read_start; |
|
ret = avail; |
|
if (copy_to_user(buffer, from, avail)) |
|
break; |
|
|
|
buffer += ret; |
|
written += ret; |
|
count -= ret; |
|
|
|
relay_file_read_consume(buf, read_start, ret); |
|
*ppos = relay_file_read_end_pos(buf, read_start, ret); |
|
} while (count); |
|
inode_unlock(file_inode(filp)); |
|
|
|
return written; |
|
} |
|
|
|
static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed) |
|
{ |
|
rbuf->bytes_consumed += bytes_consumed; |
|
|
|
if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) { |
|
relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1); |
|
rbuf->bytes_consumed %= rbuf->chan->subbuf_size; |
|
} |
|
} |
|
|
|
static void relay_pipe_buf_release(struct pipe_inode_info *pipe, |
|
struct pipe_buffer *buf) |
|
{ |
|
struct rchan_buf *rbuf; |
|
|
|
rbuf = (struct rchan_buf *)page_private(buf->page); |
|
relay_consume_bytes(rbuf, buf->private); |
|
} |
|
|
|
static const struct pipe_buf_operations relay_pipe_buf_ops = { |
|
.release = relay_pipe_buf_release, |
|
.try_steal = generic_pipe_buf_try_steal, |
|
.get = generic_pipe_buf_get, |
|
}; |
|
|
|
static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i) |
|
{ |
|
} |
|
|
|
/* |
|
* subbuf_splice_actor - splice up to one subbuf's worth of data |
|
*/ |
|
static ssize_t subbuf_splice_actor(struct file *in, |
|
loff_t *ppos, |
|
struct pipe_inode_info *pipe, |
|
size_t len, |
|
unsigned int flags, |
|
int *nonpad_ret) |
|
{ |
|
unsigned int pidx, poff, total_len, subbuf_pages, nr_pages; |
|
struct rchan_buf *rbuf = in->private_data; |
|
unsigned int subbuf_size = rbuf->chan->subbuf_size; |
|
uint64_t pos = (uint64_t) *ppos; |
|
uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size; |
|
size_t read_start = (size_t) do_div(pos, alloc_size); |
|
size_t read_subbuf = read_start / subbuf_size; |
|
size_t padding = rbuf->padding[read_subbuf]; |
|
size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding; |
|
struct page *pages[PIPE_DEF_BUFFERS]; |
|
struct partial_page partial[PIPE_DEF_BUFFERS]; |
|
struct splice_pipe_desc spd = { |
|
.pages = pages, |
|
.nr_pages = 0, |
|
.nr_pages_max = PIPE_DEF_BUFFERS, |
|
.partial = partial, |
|
.ops = &relay_pipe_buf_ops, |
|
.spd_release = relay_page_release, |
|
}; |
|
ssize_t ret; |
|
|
|
if (rbuf->subbufs_produced == rbuf->subbufs_consumed) |
|
return 0; |
|
if (splice_grow_spd(pipe, &spd)) |
|
return -ENOMEM; |
|
|
|
/* |
|
* Adjust read len, if longer than what is available |
|
*/ |
|
if (len > (subbuf_size - read_start % subbuf_size)) |
|
len = subbuf_size - read_start % subbuf_size; |
|
|
|
subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT; |
|
pidx = (read_start / PAGE_SIZE) % subbuf_pages; |
|
poff = read_start & ~PAGE_MASK; |
|
nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max); |
|
|
|
for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) { |
|
unsigned int this_len, this_end, private; |
|
unsigned int cur_pos = read_start + total_len; |
|
|
|
if (!len) |
|
break; |
|
|
|
this_len = min_t(unsigned long, len, PAGE_SIZE - poff); |
|
private = this_len; |
|
|
|
spd.pages[spd.nr_pages] = rbuf->page_array[pidx]; |
|
spd.partial[spd.nr_pages].offset = poff; |
|
|
|
this_end = cur_pos + this_len; |
|
if (this_end >= nonpad_end) { |
|
this_len = nonpad_end - cur_pos; |
|
private = this_len + padding; |
|
} |
|
spd.partial[spd.nr_pages].len = this_len; |
|
spd.partial[spd.nr_pages].private = private; |
|
|
|
len -= this_len; |
|
total_len += this_len; |
|
poff = 0; |
|
pidx = (pidx + 1) % subbuf_pages; |
|
|
|
if (this_end >= nonpad_end) { |
|
spd.nr_pages++; |
|
break; |
|
} |
|
} |
|
|
|
ret = 0; |
|
if (!spd.nr_pages) |
|
goto out; |
|
|
|
ret = *nonpad_ret = splice_to_pipe(pipe, &spd); |
|
if (ret < 0 || ret < total_len) |
|
goto out; |
|
|
|
if (read_start + ret == nonpad_end) |
|
ret += padding; |
|
|
|
out: |
|
splice_shrink_spd(&spd); |
|
return ret; |
|
} |
|
|
|
static ssize_t relay_file_splice_read(struct file *in, |
|
loff_t *ppos, |
|
struct pipe_inode_info *pipe, |
|
size_t len, |
|
unsigned int flags) |
|
{ |
|
ssize_t spliced; |
|
int ret; |
|
int nonpad_ret = 0; |
|
|
|
ret = 0; |
|
spliced = 0; |
|
|
|
while (len && !spliced) { |
|
ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret); |
|
if (ret < 0) |
|
break; |
|
else if (!ret) { |
|
if (flags & SPLICE_F_NONBLOCK) |
|
ret = -EAGAIN; |
|
break; |
|
} |
|
|
|
*ppos += ret; |
|
if (ret > len) |
|
len = 0; |
|
else |
|
len -= ret; |
|
spliced += nonpad_ret; |
|
nonpad_ret = 0; |
|
} |
|
|
|
if (spliced) |
|
return spliced; |
|
|
|
return ret; |
|
} |
|
|
|
const struct file_operations relay_file_operations = { |
|
.open = relay_file_open, |
|
.poll = relay_file_poll, |
|
.mmap = relay_file_mmap, |
|
.read = relay_file_read, |
|
.llseek = no_llseek, |
|
.release = relay_file_release, |
|
.splice_read = relay_file_splice_read, |
|
}; |
|
EXPORT_SYMBOL_GPL(relay_file_operations);
|
|
|