From: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
Joseph Qi <joseph.qi@linux.alibaba.com>,
Tejun Heo <tj@kernel.org>,
jiufei.xue@linux.alibaba.com,
Caspar Zhang <caspar@linux.alibaba.com>
Subject: [PATCH v2] cfq: clear queue pointers from cfqg after unpinning them in cfq_pd_offline
Date: Wed, 5 Sep 2018 14:51:50 +0200 [thread overview]
Message-ID: <5278cac9-399f-3e30-add8-f15642ca6b8b@maciej.szmigiero.name> (raw)
BFQ is already doing a similar thing in its .pd_offline_fn() method
implementation.
While it seems that after
commit 4c6994806f70 ("blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir()")
was reverted leaving these pointers intact no longer causes crashes
clearing them is still a sensible thing to do to make the code more robust.
Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
---
Changes from v1: Drop stable and fixes tags, rewrite the commit message
as after commit 4c6994806f70 was reverted this change is no longer
required to fix a crash.
block/cfq-iosched.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 2eb87444b157..ed41aa978c4a 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1644,14 +1644,20 @@ static void cfq_pd_offline(struct blkg_policy_data *pd)
int i;
for (i = 0; i < IOPRIO_BE_NR; i++) {
- if (cfqg->async_cfqq[0][i])
+ if (cfqg->async_cfqq[0][i]) {
cfq_put_queue(cfqg->async_cfqq[0][i]);
- if (cfqg->async_cfqq[1][i])
+ cfqg->async_cfqq[0][i] = NULL;
+ }
+ if (cfqg->async_cfqq[1][i]) {
cfq_put_queue(cfqg->async_cfqq[1][i]);
+ cfqg->async_cfqq[1][i] = NULL;
+ }
}
- if (cfqg->async_idle_cfqq)
+ if (cfqg->async_idle_cfqq) {
cfq_put_queue(cfqg->async_idle_cfqq);
+ cfqg->async_idle_cfqq = NULL;
+ }
/*
* @blkg is going offline and will be ignored by
reply other threads:[~2018-09-05 12:52 UTC|newest]
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