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ref_tracker: add a count of untracked references

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We are still chasing a netdev refcount imbalance, and we suspect
we have one rogue dev_put() that is consuming a reference taken
from a dev_hold_track()

To detect this case, allow ref_tracker_alloc() and ref_tracker_free()
to be called with a NULL @trackerp parameter, and use a dedicated
refcount_t just for them.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2022-02-04 14:42:36 -08:00 committed by David S. Miller
parent e3ececfe66
commit 8fd5522f44
2 changed files with 13 additions and 1 deletions
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2
include/linux/ref_tracker.h
View File

@ -13,6 +13,7 @@ struct ref_tracker_dir {
spinlock_t lock;
unsigned int quarantine_avail;
refcount_t untracked;
refcount_t no_tracker;
bool dead;
struct list_head list; /* List of active trackers */
struct list_head quarantine; /* List of dead trackers */
@ -29,6 +30,7 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
dir->quarantine_avail = quarantine_count;
dir->dead = false;
refcount_set(&dir->untracked, 1);
refcount_set(&dir->no_tracker, 1);
stack_depot_init();
}

12
lib/ref_tracker.c
View File

@ -38,6 +38,7 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
spin_unlock_irqrestore(&dir->lock, flags);
WARN_ON_ONCE(leak);
WARN_ON_ONCE(refcount_read(&dir->untracked) != 1);
WARN_ON_ONCE(refcount_read(&dir->no_tracker) != 1);
}
EXPORT_SYMBOL(ref_tracker_dir_exit);
@ -75,6 +76,10 @@ int ref_tracker_alloc(struct ref_tracker_dir *dir,
WARN_ON_ONCE(dir->dead);
if (!trackerp) {
refcount_inc(&dir->no_tracker);
return 0;
}
if (gfp & __GFP_DIRECT_RECLAIM)
gfp_mask |= __GFP_NOFAIL;
*trackerp = tracker = kzalloc(sizeof(*tracker), gfp_mask);
@ -98,13 +103,18 @@ int ref_tracker_free(struct ref_tracker_dir *dir,
struct ref_tracker **trackerp)
{
unsigned long entries[REF_TRACKER_STACK_ENTRIES];
struct ref_tracker *tracker = *trackerp;
depot_stack_handle_t stack_handle;
struct ref_tracker *tracker;
unsigned int nr_entries;
unsigned long flags;
WARN_ON_ONCE(dir->dead);
if (!trackerp) {
refcount_dec(&dir->no_tracker);
return 0;
}
tracker = *trackerp;
if (!tracker) {
refcount_dec(&dir->untracked);
return -EEXIST;