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authorHong Zhiguo <zhiguohong@tencent.com>2013-11-20 10:35:05 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-12-11 22:37:54 -0800
commit4830959318d14bd8856437ad5beea6016ef8c484 (patch)
treeb145a1526ee06e4589cf7bafef4f4b0ebb31a342 /block
parent7b549e29197626f361f29c0a3e444259f048702f (diff)
downloadlwn-4830959318d14bd8856437ad5beea6016ef8c484.tar.gz
lwn-4830959318d14bd8856437ad5beea6016ef8c484.zip
Update of blkg_stat and blkg_rwstat may happen in bh context. While u64_stats_fetch_retry is only preempt_disable on 32bit UP system. This is not enough to avoid preemption by bh and may read strange 64 bit value.
commit 2c575026fae6e63771bd2a4c1d407214a8096a89 upstream. Signed-off-by: Hong Zhiguo <zhiguohong@tencent.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
-rw-r--r--block/blk-cgroup.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index ae6969a7ffd4..2e34c386d760 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -430,9 +430,9 @@ static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
uint64_t v;
do {
- start = u64_stats_fetch_begin(&stat->syncp);
+ start = u64_stats_fetch_begin_bh(&stat->syncp);
v = stat->cnt;
- } while (u64_stats_fetch_retry(&stat->syncp, start));
+ } while (u64_stats_fetch_retry_bh(&stat->syncp, start));
return v;
}
@@ -498,9 +498,9 @@ static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
struct blkg_rwstat tmp;
do {
- start = u64_stats_fetch_begin(&rwstat->syncp);
+ start = u64_stats_fetch_begin_bh(&rwstat->syncp);
tmp = *rwstat;
- } while (u64_stats_fetch_retry(&rwstat->syncp, start));
+ } while (u64_stats_fetch_retry_bh(&rwstat->syncp, start));
return tmp;
}