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| author | Tao Cui <cuitao@kylinos.cn> | 2026-08-03 21:34:00 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-08-03 20:00:09 -0600 |
| commit | 3be7ad35f10e8e19f618f67ddca0bc0e247f6505 (patch) | |
| tree | 346e2ff9596083811cbc8026307000cab30c9650 /block | |
| parent | 8b5ffb43ae9d27eed9165e1962963d685d879219 (diff) | |
| download | linux-next-3be7ad35f10e8e19f618f67ddca0bc0e247f6505.tar.gz linux-next-3be7ad35f10e8e19f618f67ddca0bc0e247f6505.zip | |
block/blk-cgroup-rwstat: use data_race() for online test
blkg_rwstat_recursive_sum() reads pos_blkg->online without the queue
lock that its doc comment requires, since blkcg_print_blkgs() stopped
holding it in 56cc24f59c14. Concurrent blkg_create/destroy flips
->online, tripping KCSAN. The race is harmless (RCU-protected, stale
online only causes minor stat noise). Use data_race() to annotate
the intentional lockless read.
Also update the stale doc comment that still requires the queue lock.
Reviewed-by: Yu Kuai <yukuai@fygo.io>
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://patch.msgid.link/20260803133400.137906-1-cui.tao@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-cgroup-rwstat.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/block/blk-cgroup-rwstat.c b/block/blk-cgroup-rwstat.c index aae910713814..2e9bf081cce2 100644 --- a/block/blk-cgroup-rwstat.c +++ b/block/blk-cgroup-rwstat.c @@ -88,8 +88,7 @@ EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); * @sum: blkg_rwstat_sample structure containing the results * * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its - * online descendants and their aux counts. The caller must be holding the - * queue lock for online tests. + * online descendants and their aux counts. * * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it * is at @off bytes into @blkg's blkg_policy_data of the policy. @@ -107,7 +106,7 @@ void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol, blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) { struct blkg_rwstat *rwstat; - if (!pos_blkg->online) + if (!data_race(pos_blkg->online)) continue; if (pol) { |