From 950cda7f8e2bc6f182a2640817970166c55240db Mon Sep 17 00:00:00 2001 From: Hong Zhiguo Date: Wed, 20 Nov 2013 10:35:05 -0700 Subject: [PATCH] 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 Acked-by: Tejun Heo Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/blk-cgroup.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 4e595ee8c915..749afadfbb33 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -399,9 +399,9 @@ 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; } @@ -467,9 +467,9 @@ 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; }