Re: [PATCH v3 09/57] sched: Simplify ttwu()
From: Dan Carpenter <hidden>
Date: 2023-06-12 13:51:32
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dmaengine, linux-kbuild, linux-perf-users, lkml, llvm, rcu
On Mon, Jun 12, 2023 at 11:07:22AM +0200, Peter Zijlstra wrote:
quoted hunk ↗ jump to hunk
--- a/kernel/sched/core.c +++ b/kernel/sched/core.c@@ -3664,16 +3664,15 @@ ttwu_stat(struct task_struct *p, int cpu __schedstat_inc(p->stats.nr_wakeups_local); } else { struct sched_domain *sd; + guard(rcu)(); __schedstat_inc(p->stats.nr_wakeups_remote); - rcu_read_lock();
We can't put the guard(rcu)(); here? I have unpublished static analysis which assumes that the first and last statements guarded by a lock are important. But if we always put it at the top of the scope then we lose that information.
for_each_domain(rq->cpu, sd) {
if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
__schedstat_inc(sd->ttwu_wake_remote);
break;
}
}
- rcu_read_unlock();
}regards, dan carpenter