The following commit has been merged into the sched/rt branch of tip: Commit-ID: 9458e0a78c45bc6537ce11eb9f03489eab92f9c2 Gitweb: https://git.kernel.org/tip/9458e0a78c45bc6537ce11eb9f03489eab92f9c2 Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> AuthorDate: Thu, 25 Aug 2022 18:41:30 +02:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Mon, 19 Sep 2022 14:35:08 +02:00 flex_proportions: Disable preemption entering the write section. The seqcount fprop_global::sequence is not associated with a lock. The write section (fprop_new_period()) is invoked from a timer and since the softirq is preemptible on PREEMPT_RT it is possible to preempt the write section which is not desited. Disable preemption around the write section on PREEMPT_RT. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20220825164131.402717-8-bigeasy@xxxxxxxxxxxxx --- lib/flex_proportions.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/flex_proportions.c b/lib/flex_proportions.c index 05cccbc..83332fe 100644 --- a/lib/flex_proportions.c +++ b/lib/flex_proportions.c @@ -70,6 +70,7 @@ bool fprop_new_period(struct fprop_global *p, int periods) */ if (events <= 1) return false; + preempt_disable_nested(); write_seqcount_begin(&p->sequence); if (periods < 64) events -= events >> periods; @@ -77,6 +78,7 @@ bool fprop_new_period(struct fprop_global *p, int periods) percpu_counter_add(&p->events, -events); p->period += periods; write_seqcount_end(&p->sequence); + preempt_enable_nested(); return true; }
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