Commit 9e0c8299 authored by Bart Van Assche's avatar Bart Van Assche Committed by Jens Axboe

block: Add a comment above queue_lockdep_assert_held()

Add a comment above the queue_lockdep_assert_held() macro that
explains the purpose of the q->queue_lock test.
Signed-off-by: default avatarBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c3a148d2
......@@ -635,6 +635,13 @@ struct request_queue {
(1 << QUEUE_FLAG_SAME_COMP) | \
(1 << QUEUE_FLAG_POLL))
/*
* @q->queue_lock is set while a queue is being initialized. Since we know
* that no other threads access the queue object before @q->queue_lock has
* been set, it is safe to manipulate queue flags without holding the
* queue_lock if @q->queue_lock == NULL. See also blk_alloc_queue_node() and
* blk_init_allocated_queue().
*/
static inline void queue_lockdep_assert_held(struct request_queue *q)
{
if (q->queue_lock)
......
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