From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932138Ab3KFLQ5 (ORCPT ); Wed, 6 Nov 2013 06:16:57 -0500 Received: from mail-pd0-f180.google.com ([209.85.192.180]:35005 "EHLO mail-pd0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756467Ab3KFLQz (ORCPT ); Wed, 6 Nov 2013 06:16:55 -0500 From: Hong Zhiguo To: tj@kernel.org Cc: vgoyal@redhat.com, cgroups@vger.kernel.org, axboe@kernel.dk, linux-kernel@vger.kernel.org, Hong Zhiguo Subject: [PATCH] blkcg: have bh disable for 32bit UP system reading 64bit stats Date: Wed, 6 Nov 2013 19:14:44 +0800 Message-Id: <1383736484-393-1-git-send-email-zhiguohong@tencent.com> X-Mailer: git-send-email 1.8.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Hong Zhiguo 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 --- 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