From 6c8557bdb28df3ae97476c5e2aed6373cd235aab Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 19 May 2017 12:58:25 +0200 Subject: [PATCH] smp, cpumask: Use non-atomic cpumask_{set,clear}_cpu() The cpumasks in smp_call_function_many() are private and not subject to concurrency, atomic bitops are pointless and expensive. Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- include/linux/cpumask.h | 11 +++++++++++ kernel/smp.c | 4 ++-- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index a21b1fb9a968..4bf4479a3a80 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -293,6 +293,12 @@ static inline void cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp) set_bit(cpumask_check(cpu), cpumask_bits(dstp)); } +static inline void __cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp) +{ + __set_bit(cpumask_check(cpu), cpumask_bits(dstp)); +} + + /** * cpumask_clear_cpu - clear a cpu in a cpumask * @cpu: cpu number (< nr_cpu_ids) @@ -303,6 +309,11 @@ static inline void cpumask_clear_cpu(int cpu, struct cpumask *dstp) clear_bit(cpumask_check(cpu), cpumask_bits(dstp)); } +static inline void __cpumask_clear_cpu(int cpu, struct cpumask *dstp) +{ + __clear_bit(cpumask_check(cpu), cpumask_bits(dstp)); +} + /** * cpumask_test_cpu - test for a cpu in a cpumask * @cpu: cpu number (< nr_cpu_ids) diff --git a/kernel/smp.c b/kernel/smp.c index 76d16fe3c427..3061483cb3ad 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -436,7 +436,7 @@ void smp_call_function_many(const struct cpumask *mask, cfd = this_cpu_ptr(&cfd_data); cpumask_and(cfd->cpumask, mask, cpu_online_mask); - cpumask_clear_cpu(this_cpu, cfd->cpumask); + __cpumask_clear_cpu(this_cpu, cfd->cpumask); /* Some callers race with other cpus changing the passed mask */ if (unlikely(!cpumask_weight(cfd->cpumask))) @@ -452,7 +452,7 @@ void smp_call_function_many(const struct cpumask *mask, csd->func = func; csd->info = info; if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) - cpumask_set_cpu(cpu, cfd->cpumask_ipi); + __cpumask_set_cpu(cpu, cfd->cpumask_ipi); } /* Send a message to all CPUs in the map */