Commit 6c8557bd authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 3fc5b3b6

include/linux/cpumask.h

+11 −0
Original line number Diff line number Diff line
@@ -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)

kernel/smp.c

+2 −2
Original line number Diff line number Diff line
@@ -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 */

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