From: Hong Zhiguo <zhiguohong@xxxxxxxxxxx>
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.
Signed-off-by: Hong Zhiguo <zhiguohong@xxxxxxxxxxx>
---
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 ae6969a..2e34c38 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;
}
--
1.8.1.2
--
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