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495 lines
12 KiB
495 lines
12 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2021 VMware Inc, Steven Rostedt <[email protected]> |
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*/ |
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#include <linux/spinlock.h> |
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#include <linux/irq_work.h> |
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#include <linux/slab.h> |
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#include "trace.h" |
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/* See pid_list.h for details */ |
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static inline union lower_chunk *get_lower_chunk(struct trace_pid_list *pid_list) |
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{ |
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union lower_chunk *chunk; |
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lockdep_assert_held(&pid_list->lock); |
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if (!pid_list->lower_list) |
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return NULL; |
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chunk = pid_list->lower_list; |
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pid_list->lower_list = chunk->next; |
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pid_list->free_lower_chunks--; |
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WARN_ON_ONCE(pid_list->free_lower_chunks < 0); |
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chunk->next = NULL; |
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/* |
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* If a refill needs to happen, it can not happen here |
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* as the scheduler run queue locks are held. |
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*/ |
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if (pid_list->free_lower_chunks <= CHUNK_REALLOC) |
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irq_work_queue(&pid_list->refill_irqwork); |
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return chunk; |
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} |
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static inline union upper_chunk *get_upper_chunk(struct trace_pid_list *pid_list) |
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{ |
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union upper_chunk *chunk; |
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lockdep_assert_held(&pid_list->lock); |
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if (!pid_list->upper_list) |
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return NULL; |
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chunk = pid_list->upper_list; |
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pid_list->upper_list = chunk->next; |
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pid_list->free_upper_chunks--; |
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WARN_ON_ONCE(pid_list->free_upper_chunks < 0); |
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chunk->next = NULL; |
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/* |
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* If a refill needs to happen, it can not happen here |
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* as the scheduler run queue locks are held. |
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*/ |
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if (pid_list->free_upper_chunks <= CHUNK_REALLOC) |
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irq_work_queue(&pid_list->refill_irqwork); |
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return chunk; |
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} |
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static inline void put_lower_chunk(struct trace_pid_list *pid_list, |
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union lower_chunk *chunk) |
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{ |
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lockdep_assert_held(&pid_list->lock); |
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chunk->next = pid_list->lower_list; |
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pid_list->lower_list = chunk; |
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pid_list->free_lower_chunks++; |
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} |
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static inline void put_upper_chunk(struct trace_pid_list *pid_list, |
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union upper_chunk *chunk) |
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{ |
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lockdep_assert_held(&pid_list->lock); |
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chunk->next = pid_list->upper_list; |
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pid_list->upper_list = chunk; |
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pid_list->free_upper_chunks++; |
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} |
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static inline bool upper_empty(union upper_chunk *chunk) |
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{ |
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/* |
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* If chunk->data has no lower chunks, it will be the same |
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* as a zeroed bitmask. Use find_first_bit() to test it |
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* and if it doesn't find any bits set, then the array |
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* is empty. |
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*/ |
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int bit = find_first_bit((unsigned long *)chunk->data, |
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sizeof(chunk->data) * 8); |
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return bit >= sizeof(chunk->data) * 8; |
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} |
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static inline int pid_split(unsigned int pid, unsigned int *upper1, |
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unsigned int *upper2, unsigned int *lower) |
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{ |
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/* MAX_PID should cover all pids */ |
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BUILD_BUG_ON(MAX_PID < PID_MAX_LIMIT); |
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/* In case a bad pid is passed in, then fail */ |
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if (unlikely(pid >= MAX_PID)) |
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return -1; |
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*upper1 = (pid >> UPPER1_SHIFT) & UPPER_MASK; |
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*upper2 = (pid >> UPPER2_SHIFT) & UPPER_MASK; |
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*lower = pid & LOWER_MASK; |
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return 0; |
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} |
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static inline unsigned int pid_join(unsigned int upper1, |
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unsigned int upper2, unsigned int lower) |
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{ |
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return ((upper1 & UPPER_MASK) << UPPER1_SHIFT) | |
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((upper2 & UPPER_MASK) << UPPER2_SHIFT) | |
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(lower & LOWER_MASK); |
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} |
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/** |
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* trace_pid_list_is_set - test if the pid is set in the list |
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* @pid_list: The pid list to test |
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* @pid: The pid to to see if set in the list. |
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* |
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* Tests if @pid is is set in the @pid_list. This is usually called |
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* from the scheduler when a task is scheduled. Its pid is checked |
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* if it should be traced or not. |
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* |
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* Return true if the pid is in the list, false otherwise. |
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*/ |
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bool trace_pid_list_is_set(struct trace_pid_list *pid_list, unsigned int pid) |
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{ |
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union upper_chunk *upper_chunk; |
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union lower_chunk *lower_chunk; |
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unsigned long flags; |
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unsigned int upper1; |
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unsigned int upper2; |
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unsigned int lower; |
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bool ret = false; |
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if (!pid_list) |
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return false; |
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if (pid_split(pid, &upper1, &upper2, &lower) < 0) |
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return false; |
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raw_spin_lock_irqsave(&pid_list->lock, flags); |
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upper_chunk = pid_list->upper[upper1]; |
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if (upper_chunk) { |
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lower_chunk = upper_chunk->data[upper2]; |
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if (lower_chunk) |
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ret = test_bit(lower, lower_chunk->data); |
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} |
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raw_spin_unlock_irqrestore(&pid_list->lock, flags); |
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return ret; |
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} |
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/** |
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* trace_pid_list_set - add a pid to the list |
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* @pid_list: The pid list to add the @pid to. |
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* @pid: The pid to add. |
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* |
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* Adds @pid to @pid_list. This is usually done explicitly by a user |
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* adding a task to be traced, or indirectly by the fork function |
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* when children should be traced and a task's pid is in the list. |
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* |
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* Return 0 on success, negative otherwise. |
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*/ |
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int trace_pid_list_set(struct trace_pid_list *pid_list, unsigned int pid) |
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{ |
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union upper_chunk *upper_chunk; |
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union lower_chunk *lower_chunk; |
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unsigned long flags; |
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unsigned int upper1; |
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unsigned int upper2; |
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unsigned int lower; |
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int ret; |
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if (!pid_list) |
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return -ENODEV; |
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if (pid_split(pid, &upper1, &upper2, &lower) < 0) |
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return -EINVAL; |
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raw_spin_lock_irqsave(&pid_list->lock, flags); |
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upper_chunk = pid_list->upper[upper1]; |
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if (!upper_chunk) { |
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upper_chunk = get_upper_chunk(pid_list); |
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if (!upper_chunk) { |
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ret = -ENOMEM; |
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goto out; |
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} |
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pid_list->upper[upper1] = upper_chunk; |
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} |
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lower_chunk = upper_chunk->data[upper2]; |
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if (!lower_chunk) { |
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lower_chunk = get_lower_chunk(pid_list); |
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if (!lower_chunk) { |
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ret = -ENOMEM; |
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goto out; |
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} |
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upper_chunk->data[upper2] = lower_chunk; |
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} |
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set_bit(lower, lower_chunk->data); |
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ret = 0; |
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out: |
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raw_spin_unlock_irqrestore(&pid_list->lock, flags); |
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return ret; |
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} |
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/** |
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* trace_pid_list_clear - remove a pid from the list |
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* @pid_list: The pid list to remove the @pid from. |
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* @pid: The pid to remove. |
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* |
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* Removes @pid from @pid_list. This is usually done explicitly by a user |
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* removing tasks from tracing, or indirectly by the exit function |
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* when a task that is set to be traced exits. |
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* |
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* Return 0 on success, negative otherwise. |
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*/ |
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int trace_pid_list_clear(struct trace_pid_list *pid_list, unsigned int pid) |
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{ |
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union upper_chunk *upper_chunk; |
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union lower_chunk *lower_chunk; |
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unsigned long flags; |
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unsigned int upper1; |
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unsigned int upper2; |
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unsigned int lower; |
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if (!pid_list) |
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return -ENODEV; |
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if (pid_split(pid, &upper1, &upper2, &lower) < 0) |
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return -EINVAL; |
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raw_spin_lock_irqsave(&pid_list->lock, flags); |
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upper_chunk = pid_list->upper[upper1]; |
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if (!upper_chunk) |
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goto out; |
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lower_chunk = upper_chunk->data[upper2]; |
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if (!lower_chunk) |
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goto out; |
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clear_bit(lower, lower_chunk->data); |
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/* if there's no more bits set, add it to the free list */ |
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if (find_first_bit(lower_chunk->data, LOWER_MAX) >= LOWER_MAX) { |
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put_lower_chunk(pid_list, lower_chunk); |
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upper_chunk->data[upper2] = NULL; |
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if (upper_empty(upper_chunk)) { |
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put_upper_chunk(pid_list, upper_chunk); |
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pid_list->upper[upper1] = NULL; |
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} |
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} |
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out: |
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raw_spin_unlock_irqrestore(&pid_list->lock, flags); |
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return 0; |
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} |
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/** |
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* trace_pid_list_next - return the next pid in the list |
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* @pid_list: The pid list to examine. |
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* @pid: The pid to start from |
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* @next: The pointer to place the pid that is set starting from @pid. |
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* |
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* Looks for the next consecutive pid that is in @pid_list starting |
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* at the pid specified by @pid. If one is set (including @pid), then |
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* that pid is placed into @next. |
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* |
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* Return 0 when a pid is found, -1 if there are no more pids included. |
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*/ |
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int trace_pid_list_next(struct trace_pid_list *pid_list, unsigned int pid, |
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unsigned int *next) |
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{ |
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union upper_chunk *upper_chunk; |
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union lower_chunk *lower_chunk; |
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unsigned long flags; |
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unsigned int upper1; |
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unsigned int upper2; |
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unsigned int lower; |
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if (!pid_list) |
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return -ENODEV; |
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if (pid_split(pid, &upper1, &upper2, &lower) < 0) |
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return -EINVAL; |
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raw_spin_lock_irqsave(&pid_list->lock, flags); |
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for (; upper1 <= UPPER_MASK; upper1++, upper2 = 0) { |
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upper_chunk = pid_list->upper[upper1]; |
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if (!upper_chunk) |
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continue; |
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for (; upper2 <= UPPER_MASK; upper2++, lower = 0) { |
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lower_chunk = upper_chunk->data[upper2]; |
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if (!lower_chunk) |
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continue; |
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lower = find_next_bit(lower_chunk->data, LOWER_MAX, |
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lower); |
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if (lower < LOWER_MAX) |
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goto found; |
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} |
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} |
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found: |
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raw_spin_unlock_irqrestore(&pid_list->lock, flags); |
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if (upper1 > UPPER_MASK) |
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return -1; |
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*next = pid_join(upper1, upper2, lower); |
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return 0; |
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} |
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/** |
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* trace_pid_list_first - return the first pid in the list |
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* @pid_list: The pid list to examine. |
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* @pid: The pointer to place the pid first found pid that is set. |
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* |
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* Looks for the first pid that is set in @pid_list, and places it |
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* into @pid if found. |
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* |
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* Return 0 when a pid is found, -1 if there are no pids set. |
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*/ |
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int trace_pid_list_first(struct trace_pid_list *pid_list, unsigned int *pid) |
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{ |
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return trace_pid_list_next(pid_list, 0, pid); |
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} |
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static void pid_list_refill_irq(struct irq_work *iwork) |
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{ |
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struct trace_pid_list *pid_list = container_of(iwork, struct trace_pid_list, |
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refill_irqwork); |
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union upper_chunk *upper = NULL; |
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union lower_chunk *lower = NULL; |
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union upper_chunk **upper_next = &upper; |
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union lower_chunk **lower_next = &lower; |
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int upper_count; |
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int lower_count; |
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int ucnt = 0; |
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int lcnt = 0; |
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again: |
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raw_spin_lock(&pid_list->lock); |
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upper_count = CHUNK_ALLOC - pid_list->free_upper_chunks; |
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lower_count = CHUNK_ALLOC - pid_list->free_lower_chunks; |
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raw_spin_unlock(&pid_list->lock); |
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if (upper_count <= 0 && lower_count <= 0) |
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return; |
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while (upper_count-- > 0) { |
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union upper_chunk *chunk; |
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chunk = kzalloc(sizeof(*chunk), GFP_KERNEL); |
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if (!chunk) |
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break; |
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*upper_next = chunk; |
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upper_next = &chunk->next; |
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ucnt++; |
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} |
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while (lower_count-- > 0) { |
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union lower_chunk *chunk; |
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chunk = kzalloc(sizeof(*chunk), GFP_KERNEL); |
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if (!chunk) |
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break; |
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*lower_next = chunk; |
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lower_next = &chunk->next; |
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lcnt++; |
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} |
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raw_spin_lock(&pid_list->lock); |
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if (upper) { |
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*upper_next = pid_list->upper_list; |
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pid_list->upper_list = upper; |
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pid_list->free_upper_chunks += ucnt; |
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} |
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if (lower) { |
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*lower_next = pid_list->lower_list; |
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pid_list->lower_list = lower; |
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pid_list->free_lower_chunks += lcnt; |
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} |
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raw_spin_unlock(&pid_list->lock); |
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/* |
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* On success of allocating all the chunks, both counters |
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* will be less than zero. If they are not, then an allocation |
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* failed, and we should not try again. |
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*/ |
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if (upper_count >= 0 || lower_count >= 0) |
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return; |
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/* |
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* When the locks were released, free chunks could have |
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* been used and allocation needs to be done again. Might as |
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* well allocate it now. |
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*/ |
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goto again; |
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} |
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/** |
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* trace_pid_list_alloc - create a new pid_list |
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* |
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* Allocates a new pid_list to store pids into. |
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* |
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* Returns the pid_list on success, NULL otherwise. |
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*/ |
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struct trace_pid_list *trace_pid_list_alloc(void) |
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{ |
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struct trace_pid_list *pid_list; |
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int i; |
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/* According to linux/thread.h, pids can be no bigger that 30 bits */ |
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WARN_ON_ONCE(pid_max > (1 << 30)); |
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pid_list = kzalloc(sizeof(*pid_list), GFP_KERNEL); |
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if (!pid_list) |
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return NULL; |
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init_irq_work(&pid_list->refill_irqwork, pid_list_refill_irq); |
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raw_spin_lock_init(&pid_list->lock); |
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for (i = 0; i < CHUNK_ALLOC; i++) { |
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union upper_chunk *chunk; |
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chunk = kzalloc(sizeof(*chunk), GFP_KERNEL); |
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if (!chunk) |
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break; |
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chunk->next = pid_list->upper_list; |
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pid_list->upper_list = chunk; |
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pid_list->free_upper_chunks++; |
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} |
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for (i = 0; i < CHUNK_ALLOC; i++) { |
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union lower_chunk *chunk; |
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chunk = kzalloc(sizeof(*chunk), GFP_KERNEL); |
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if (!chunk) |
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break; |
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chunk->next = pid_list->lower_list; |
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pid_list->lower_list = chunk; |
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pid_list->free_lower_chunks++; |
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} |
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return pid_list; |
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} |
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/** |
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* trace_pid_list_free - Frees an allocated pid_list. |
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* |
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* Frees the memory for a pid_list that was allocated. |
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*/ |
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void trace_pid_list_free(struct trace_pid_list *pid_list) |
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{ |
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union upper_chunk *upper; |
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union lower_chunk *lower; |
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int i, j; |
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if (!pid_list) |
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return; |
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irq_work_sync(&pid_list->refill_irqwork); |
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while (pid_list->lower_list) { |
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union lower_chunk *chunk; |
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chunk = pid_list->lower_list; |
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pid_list->lower_list = pid_list->lower_list->next; |
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kfree(chunk); |
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} |
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while (pid_list->upper_list) { |
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union upper_chunk *chunk; |
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chunk = pid_list->upper_list; |
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pid_list->upper_list = pid_list->upper_list->next; |
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kfree(chunk); |
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} |
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for (i = 0; i < UPPER1_SIZE; i++) { |
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upper = pid_list->upper[i]; |
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if (upper) { |
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for (j = 0; j < UPPER2_SIZE; j++) { |
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lower = upper->data[j]; |
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kfree(lower); |
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} |
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kfree(upper); |
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} |
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} |
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kfree(pid_list); |
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}
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