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cgroup: rstat: Mark benign data race to silence KCSAN

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There is a race between updaters and flushers (flush can possibly miss
the latest update(s)). This is expected as explained in
cgroup_rstat_updated() comment, add also machine readable annotation so
that KCSAN results aren't noisy.

Reported-by: Hao Sun <sunhao.th@gmail.com>
Link: https://lore.kernel.org/r/CACkBjsbPVdkub=e-E-p1WBOLxS515ith-53SFdmFHWV_QMo40w@mail.gmail.com
Suggested-by: Hao Sun <sunhao.th@gmail.com>

Signed-off-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Michal Koutný 2021-11-03 17:58:45 +01:00 committed by Tejun Heo
parent 8ab7745879
commit eda09706b2
1 changed files with 1 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
kernel/cgroup/rstat.c
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@ -35,7 +35,7 @@ void cgroup_rstat_updated(struct cgroup *cgrp, int cpu)
* instead of NULL, we can tell whether @cgrp is on the list by * instead of NULL, we can tell whether @cgrp is on the list by
* testing the next pointer for NULL. * testing the next pointer for NULL.
*/ */
if (cgroup_rstat_cpu(cgrp, cpu)->updated_next) if (data_race(cgroup_rstat_cpu(cgrp, cpu)->updated_next))
return; return;
raw_spin_lock_irqsave(cpu_lock, flags); raw_spin_lock_irqsave(cpu_lock, flags);