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![Andrzej Hajda](/assets/img/avatar_default.png)
Library can handle allocation failures. To avoid allocation warnings __GFP_NOWARN has been added everywhere. Moreover GFP_ATOMIC has been replaced with GFP_NOWAIT in case of stack allocation on tracker free call. Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
275 lines
6.7 KiB
C
275 lines
6.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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#define pr_fmt(fmt) "ref_tracker: " fmt
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#include <linux/export.h>
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#include <linux/list_sort.h>
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#include <linux/ref_tracker.h>
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#include <linux/slab.h>
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#include <linux/stacktrace.h>
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#include <linux/stackdepot.h>
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#define REF_TRACKER_STACK_ENTRIES 16
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#define STACK_BUF_SIZE 1024
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struct ref_tracker {
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struct list_head head; /* anchor into dir->list or dir->quarantine */
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bool dead;
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depot_stack_handle_t alloc_stack_handle;
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depot_stack_handle_t free_stack_handle;
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};
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struct ref_tracker_dir_stats {
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int total;
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int count;
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struct {
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depot_stack_handle_t stack_handle;
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unsigned int count;
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} stacks[];
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};
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static struct ref_tracker_dir_stats *
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ref_tracker_get_stats(struct ref_tracker_dir *dir, unsigned int limit)
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{
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struct ref_tracker_dir_stats *stats;
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struct ref_tracker *tracker;
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stats = kmalloc(struct_size(stats, stacks, limit),
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GFP_NOWAIT | __GFP_NOWARN);
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if (!stats)
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return ERR_PTR(-ENOMEM);
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stats->total = 0;
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stats->count = 0;
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list_for_each_entry(tracker, &dir->list, head) {
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depot_stack_handle_t stack = tracker->alloc_stack_handle;
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int i;
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++stats->total;
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for (i = 0; i < stats->count; ++i)
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if (stats->stacks[i].stack_handle == stack)
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break;
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if (i >= limit)
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continue;
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if (i >= stats->count) {
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stats->stacks[i].stack_handle = stack;
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stats->stacks[i].count = 0;
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++stats->count;
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}
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++stats->stacks[i].count;
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}
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return stats;
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}
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struct ostream {
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char *buf;
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int size, used;
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};
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#define pr_ostream(stream, fmt, args...) \
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({ \
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struct ostream *_s = (stream); \
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\
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if (!_s->buf) { \
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pr_err(fmt, ##args); \
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} else { \
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int ret, len = _s->size - _s->used; \
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ret = snprintf(_s->buf + _s->used, len, pr_fmt(fmt), ##args); \
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_s->used += min(ret, len); \
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} \
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})
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static void
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__ref_tracker_dir_pr_ostream(struct ref_tracker_dir *dir,
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unsigned int display_limit, struct ostream *s)
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{
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struct ref_tracker_dir_stats *stats;
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unsigned int i = 0, skipped;
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depot_stack_handle_t stack;
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char *sbuf;
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lockdep_assert_held(&dir->lock);
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if (list_empty(&dir->list))
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return;
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stats = ref_tracker_get_stats(dir, display_limit);
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if (IS_ERR(stats)) {
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pr_ostream(s, "%s@%pK: couldn't get stats, error %pe\n",
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dir->name, dir, stats);
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return;
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}
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sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT | __GFP_NOWARN);
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for (i = 0, skipped = stats->total; i < stats->count; ++i) {
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stack = stats->stacks[i].stack_handle;
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if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
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sbuf[0] = 0;
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pr_ostream(s, "%s@%pK has %d/%d users at\n%s\n", dir->name, dir,
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stats->stacks[i].count, stats->total, sbuf);
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skipped -= stats->stacks[i].count;
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}
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if (skipped)
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pr_ostream(s, "%s@%pK skipped reports about %d/%d users.\n",
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dir->name, dir, skipped, stats->total);
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kfree(sbuf);
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kfree(stats);
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}
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void ref_tracker_dir_print_locked(struct ref_tracker_dir *dir,
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unsigned int display_limit)
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{
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struct ostream os = {};
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__ref_tracker_dir_pr_ostream(dir, display_limit, &os);
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}
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EXPORT_SYMBOL(ref_tracker_dir_print_locked);
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void ref_tracker_dir_print(struct ref_tracker_dir *dir,
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unsigned int display_limit)
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{
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unsigned long flags;
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spin_lock_irqsave(&dir->lock, flags);
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ref_tracker_dir_print_locked(dir, display_limit);
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spin_unlock_irqrestore(&dir->lock, flags);
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}
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EXPORT_SYMBOL(ref_tracker_dir_print);
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int ref_tracker_dir_snprint(struct ref_tracker_dir *dir, char *buf, size_t size)
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{
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struct ostream os = { .buf = buf, .size = size };
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unsigned long flags;
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spin_lock_irqsave(&dir->lock, flags);
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__ref_tracker_dir_pr_ostream(dir, 16, &os);
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spin_unlock_irqrestore(&dir->lock, flags);
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return os.used;
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}
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EXPORT_SYMBOL(ref_tracker_dir_snprint);
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void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
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{
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struct ref_tracker *tracker, *n;
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unsigned long flags;
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bool leak = false;
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dir->dead = true;
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spin_lock_irqsave(&dir->lock, flags);
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list_for_each_entry_safe(tracker, n, &dir->quarantine, head) {
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list_del(&tracker->head);
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kfree(tracker);
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dir->quarantine_avail++;
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}
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if (!list_empty(&dir->list)) {
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ref_tracker_dir_print_locked(dir, 16);
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leak = true;
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list_for_each_entry_safe(tracker, n, &dir->list, head) {
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list_del(&tracker->head);
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kfree(tracker);
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}
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}
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spin_unlock_irqrestore(&dir->lock, flags);
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WARN_ON_ONCE(leak);
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WARN_ON_ONCE(refcount_read(&dir->untracked) != 1);
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WARN_ON_ONCE(refcount_read(&dir->no_tracker) != 1);
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}
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EXPORT_SYMBOL(ref_tracker_dir_exit);
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int ref_tracker_alloc(struct ref_tracker_dir *dir,
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struct ref_tracker **trackerp,
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gfp_t gfp)
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{
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unsigned long entries[REF_TRACKER_STACK_ENTRIES];
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struct ref_tracker *tracker;
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unsigned int nr_entries;
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gfp_t gfp_mask = gfp | __GFP_NOWARN;
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unsigned long flags;
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WARN_ON_ONCE(dir->dead);
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if (!trackerp) {
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refcount_inc(&dir->no_tracker);
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return 0;
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}
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if (gfp & __GFP_DIRECT_RECLAIM)
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gfp_mask |= __GFP_NOFAIL;
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*trackerp = tracker = kzalloc(sizeof(*tracker), gfp_mask);
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if (unlikely(!tracker)) {
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pr_err_once("memory allocation failure, unreliable refcount tracker.\n");
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refcount_inc(&dir->untracked);
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return -ENOMEM;
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}
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nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
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tracker->alloc_stack_handle = stack_depot_save(entries, nr_entries, gfp);
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spin_lock_irqsave(&dir->lock, flags);
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list_add(&tracker->head, &dir->list);
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spin_unlock_irqrestore(&dir->lock, flags);
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return 0;
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}
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EXPORT_SYMBOL_GPL(ref_tracker_alloc);
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int ref_tracker_free(struct ref_tracker_dir *dir,
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struct ref_tracker **trackerp)
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{
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unsigned long entries[REF_TRACKER_STACK_ENTRIES];
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depot_stack_handle_t stack_handle;
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struct ref_tracker *tracker;
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unsigned int nr_entries;
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unsigned long flags;
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WARN_ON_ONCE(dir->dead);
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if (!trackerp) {
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refcount_dec(&dir->no_tracker);
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return 0;
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}
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tracker = *trackerp;
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if (!tracker) {
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refcount_dec(&dir->untracked);
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return -EEXIST;
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}
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nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
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stack_handle = stack_depot_save(entries, nr_entries,
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GFP_NOWAIT | __GFP_NOWARN);
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spin_lock_irqsave(&dir->lock, flags);
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if (tracker->dead) {
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pr_err("reference already released.\n");
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if (tracker->alloc_stack_handle) {
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pr_err("allocated in:\n");
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stack_depot_print(tracker->alloc_stack_handle);
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}
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if (tracker->free_stack_handle) {
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pr_err("freed in:\n");
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stack_depot_print(tracker->free_stack_handle);
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}
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spin_unlock_irqrestore(&dir->lock, flags);
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WARN_ON_ONCE(1);
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return -EINVAL;
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}
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tracker->dead = true;
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tracker->free_stack_handle = stack_handle;
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list_move_tail(&tracker->head, &dir->quarantine);
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if (!dir->quarantine_avail) {
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tracker = list_first_entry(&dir->quarantine, struct ref_tracker, head);
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list_del(&tracker->head);
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} else {
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dir->quarantine_avail--;
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tracker = NULL;
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}
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spin_unlock_irqrestore(&dir->lock, flags);
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kfree(tracker);
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return 0;
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}
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EXPORT_SYMBOL_GPL(ref_tracker_free);
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