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authorTejun Heo <tj@kernel.org>2012-03-05 13:15:22 -0800
committerJens Axboe <axboe@kernel.dk>2012-03-06 21:27:24 +0100
commitc875f4d0250a1f070fa26087a73bdd8f54c48100 (patch)
tree4ed2bae2fc48e54ac712d28eaaae8217c8064c1d /include/linux/blkdev.h
parent9f13ef678efd977487fc0c2e489f17c9a8c67a3e (diff)
downloadvexpress-lsk-c875f4d0250a1f070fa26087a73bdd8f54c48100.tar.gz
blkcg: drop unnecessary RCU locking
Now that blkg additions / removals are always done under both q and blkcg locks, the only places RCU locking is necessary are blkg_lookup[_create]() for lookup w/o blkcg lock. This patch drops unncessary RCU locking replacing it with plain blkcg locking as necessary. * blkiocg_pre_destroy() already perform proper locking and don't need RCU. Dropped. * blkio_read_blkg_stats() now uses blkcg->lock instead of RCU read lock. This isn't a hot path. * Now unnecessary synchronize_rcu() from queue exit paths removed. This makes q->nr_blkgs unnecessary. Dropped. * RCU annotation on blkg->q removed. -v2: Vivek pointed out that blkg_lookup_create() still needs to be called under rcu_read_lock(). Updated. -v3: After the update, stats_lock locking in blkio_read_blkg_stats() shouldn't be using _irq variant as it otherwise ends up enabling irq while blkcg->lock is locked. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/blkdev.h')
-rw-r--r--include/linux/blkdev.h1
1 files changed, 0 insertions, 1 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b4d1d4bfc16..33f1b29e53f 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -365,7 +365,6 @@ struct request_queue {
#ifdef CONFIG_BLK_CGROUP
/* XXX: array size hardcoded to avoid include dependency (temporary) */
struct list_head blkg_list;
- int nr_blkgs;
#endif
struct queue_limits limits;