Commit 8fd5522f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ref_tracker: add a count of untracked references 



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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e3ececfe

include/linux/ref_tracker.h

+2 −0
Original line number Diff line number Diff line
@@ -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();

}

lib/ref_tracker.c

+11 −1
Original line number Diff line number Diff line
@@ -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;