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Subject[RESEND][PATCH v2] cfq: clear queue pointers from cfqg after unpinning them in cfq_pd_offline
Date
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 d219e9a1af65..6a3d87dd3c1a 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
--
2.17.0
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