The following commit has been merged into the sched/core branch of tip: Commit-ID: 0019699518cc026b5bd912425be8e424843d5b33 Gitweb: https://git.kernel.org/tip/0019699518cc026b5bd912425be8e424843d5b33 Author: Yejune Deng <yejune.deng@xxxxxxxxx> AuthorDate: Mon, 10 May 2021 16:10:24 +01:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Tue, 18 May 2021 12:53:54 +02:00 lib/smp_processor_id: Use is_percpu_thread() instead of nr_cpus_allowed is_percpu_thread() more elegantly handles SMP vs UP, and further checks the presence of PF_NO_SETAFFINITY. This lets us catch cases where check_preemption_disabled() can race with a concurrent sched_setaffinity(). [Amended changelog] Signed-off-by: Valentin Schneider <valentin.schneider@xxxxxxx> Signed-off-by: Yejune Deng <yejune.deng@xxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20210510151024.2448573-3-valentin.schneider@xxxxxxx --- lib/smp_processor_id.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c index 1c1dbd3..046ac62 100644 --- a/lib/smp_processor_id.c +++ b/lib/smp_processor_id.c @@ -19,11 +19,7 @@ unsigned int check_preemption_disabled(const char *what1, const char *what2) if (irqs_disabled()) goto out; - /* - * Kernel threads bound to a single CPU can safely use - * smp_processor_id(): - */ - if (current->nr_cpus_allowed == 1) + if (is_percpu_thread()) goto out; #ifdef CONFIG_SMP
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