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authorTejun Heo <tj@kernel.org>2012-02-15 09:45:52 +0100
committerJens Axboe <axboe@kernel.dk>2012-02-15 09:45:52 +0100
commit2274b029f640cd652ab59c363e5beebf5f50e609 (patch)
tree652a2e774c537b83cd70481a936f5c7485436491 /block/blk-ioc.c
parentd705ae6b133f9f6a8beee617b1224b6a5c99c5da (diff)
downloadlinux-linaro-stable-2274b029f640cd652ab59c363e5beebf5f50e609.tar.gz
block: simplify ioc_release_fn()
Reverse double lock dancing in ioc_release_fn() can be simplified by just using trylock on the queue_lock and back out from ioc lock on trylock failure. Simplify it. Signed-off-by: Tejun Heo <tj@kernel.org> Tested-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-ioc.c')
-rw-r--r--block/blk-ioc.c46
1 files changed, 10 insertions, 36 deletions
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 811879c752e4..f53c80ecaf07 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -79,7 +79,6 @@ static void ioc_release_fn(struct work_struct *work)
{
struct io_context *ioc = container_of(work, struct io_context,
release_work);
- struct request_queue *last_q = NULL;
unsigned long flags;
/*
@@ -93,44 +92,19 @@ static void ioc_release_fn(struct work_struct *work)
while (!hlist_empty(&ioc->icq_list)) {
struct io_cq *icq = hlist_entry(ioc->icq_list.first,
struct io_cq, ioc_node);
- struct request_queue *this_q = icq->q;
-
- if (this_q != last_q) {
- /*
- * Need to switch to @this_q. Once we release
- * @ioc->lock, it can go away along with @cic.
- * Hold on to it.
- */
- __blk_get_queue(this_q);
-
- /*
- * blk_put_queue() might sleep thanks to kobject
- * idiocy. Always release both locks, put and
- * restart.
- */
- if (last_q) {
- spin_unlock(last_q->queue_lock);
- spin_unlock_irqrestore(&ioc->lock, flags);
- blk_put_queue(last_q);
- } else {
- spin_unlock_irqrestore(&ioc->lock, flags);
- }
-
- last_q = this_q;
- spin_lock_irqsave(this_q->queue_lock, flags);
- spin_lock_nested(&ioc->lock, 1);
- continue;
+ struct request_queue *q = icq->q;
+
+ if (spin_trylock(q->queue_lock)) {
+ ioc_exit_icq(icq);
+ spin_unlock(q->queue_lock);
+ } else {
+ spin_unlock_irqrestore(&ioc->lock, flags);
+ cpu_relax();
+ spin_lock_irqsave_nested(&ioc->lock, flags, 1);
}
- ioc_exit_icq(icq);
}
- if (last_q) {
- spin_unlock(last_q->queue_lock);
- spin_unlock_irqrestore(&ioc->lock, flags);
- blk_put_queue(last_q);
- } else {
- spin_unlock_irqrestore(&ioc->lock, flags);
- }
+ spin_unlock_irqrestore(&ioc->lock, flags);
kmem_cache_free(iocontext_cachep, ioc);
}