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author | Tejun Heo <tj@kernel.org> | 2012-03-05 13:15:22 -0800 |
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committer | Jens Axboe <axboe@kernel.dk> | 2012-03-06 21:27:24 +0100 |
commit | c875f4d0250a1f070fa26087a73bdd8f54c48100 (patch) | |
tree | 4ed2bae2fc48e54ac712d28eaaae8217c8064c1d /include/linux/blkdev.h | |
parent | 9f13ef678efd977487fc0c2e489f17c9a8c67a3e (diff) | |
download | linux-stable-c875f4d0250a1f070fa26087a73bdd8f54c48100.tar.gz linux-stable-c875f4d0250a1f070fa26087a73bdd8f54c48100.tar.bz2 linux-stable-c875f4d0250a1f070fa26087a73bdd8f54c48100.zip |
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.h | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index b4d1d4bfc168..33f1b29e53f4 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; |