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lib/smp_processor_id: Use is_percpu_thread() instead of nr_cpus_allowed

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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().

Signed-off-by: Yejune Deng <yejune.deng@gmail.com>
[Amended changelog]
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210510151024.2448573-3-valentin.schneider@arm.com
This commit is contained in:
Yejune Deng 2021-05-10 16:10:24 +01:00 committed by Peter Zijlstra
parent 00b89fe019
commit 570a752b7a
1 changed files with 1 additions and 5 deletions
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6
lib/smp_processor_id.c
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@ -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