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irda: Fix lockdep annotations in hashbin_delete().
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A nested lock depth was added to the hasbin_delete() code but it
doesn't actually work some well and results in tons of lockdep splats.

Fix the code instead to properly drop the lock around the operation
and just keep peeking the head of the hashbin queue.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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davem330 committed Feb 17, 2017
1 parent 22f0708 commit 4c03b86
Showing 1 changed file with 16 additions and 18 deletions.
34 changes: 16 additions & 18 deletions net/irda/irqueue.c
Original file line number Diff line number Diff line change
Expand Up @@ -383,9 +383,6 @@ EXPORT_SYMBOL(hashbin_new);
* for deallocating this structure if it's complex. If not the user can
* just supply kfree, which should take care of the job.
*/
#ifdef CONFIG_LOCKDEP
static int hashbin_lock_depth = 0;
#endif
int hashbin_delete( hashbin_t* hashbin, FREE_FUNC free_func)
{
irda_queue_t* queue;
Expand All @@ -396,22 +393,27 @@ int hashbin_delete( hashbin_t* hashbin, FREE_FUNC free_func)
IRDA_ASSERT(hashbin->magic == HB_MAGIC, return -1;);

/* Synchronize */
if ( hashbin->hb_type & HB_LOCK ) {
spin_lock_irqsave_nested(&hashbin->hb_spinlock, flags,
hashbin_lock_depth++);
}
if (hashbin->hb_type & HB_LOCK)
spin_lock_irqsave(&hashbin->hb_spinlock, flags);

/*
* Free the entries in the hashbin, TODO: use hashbin_clear when
* it has been shown to work
*/
for (i = 0; i < HASHBIN_SIZE; i ++ ) {
queue = dequeue_first((irda_queue_t**) &hashbin->hb_queue[i]);
while (queue ) {
if (free_func)
(*free_func)(queue);
queue = dequeue_first(
(irda_queue_t**) &hashbin->hb_queue[i]);
while (1) {
queue = dequeue_first((irda_queue_t**) &hashbin->hb_queue[i]);

if (!queue)
break;

if (free_func) {
if (hashbin->hb_type & HB_LOCK)
spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
free_func(queue);
if (hashbin->hb_type & HB_LOCK)
spin_lock_irqsave(&hashbin->hb_spinlock, flags);
}
}
}

Expand All @@ -420,12 +422,8 @@ int hashbin_delete( hashbin_t* hashbin, FREE_FUNC free_func)
hashbin->magic = ~HB_MAGIC;

/* Release lock */
if ( hashbin->hb_type & HB_LOCK) {
if (hashbin->hb_type & HB_LOCK)
spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
#ifdef CONFIG_LOCKDEP
hashbin_lock_depth--;
#endif
}

/*
* Free the hashbin structure
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