Commit 2ea6dec4 authored by Rusty Russell's avatar Rusty Russell Committed by Thomas Gleixner
Browse files

generic-ipi: Add smp_call_function_any() 



Andrew points out that acpi-cpufreq uses cpumask_any, when it really
would prefer to use the same CPU if possible (to avoid an IPI).  In
general, this seems a good idea to offer.

[ tglx: Documented selection preference and Inlined the UP case to
  	avoid the copy of smp_call_function_single() and the extra
  	EXPORT ]

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Zhao Yakui <yakui.zhao@intel.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 72f279b2

include/linux/smp.h

+10 −1
Original line number Diff line number Diff line
@@ -76,6 +76,9 @@ void smp_call_function_many(const struct cpumask *mask, 
void __smp_call_function_single(int cpuid, struct call_single_data *data,

				int wait);



int smp_call_function_any(const struct cpumask *mask,

			  void (*func)(void *info), void *info, int wait);



/*

 * Generic and arch helpers

 */
@@ -137,9 +140,15 @@ static inline void smp_send_reschedule(int cpu) { } 
#define smp_prepare_boot_cpu()			do {} while (0)

#define smp_call_function_many(mask, func, info, wait) \

			(up_smp_call_function(func, info))

static inline void init_call_single_data(void)

static inline void init_call_single_data(void) { }



static inline int

smp_call_function_any(const struct cpumask *mask, void (*func)(void *info),

		      void *info, int wait)

{

	return smp_call_function_single(0, func, info, wait);

}



#endif /* !SMP */



/*

kernel/smp.c

+45 −0
Original line number Diff line number Diff line
@@ -319,6 +319,51 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info, 
}

EXPORT_SYMBOL(smp_call_function_single);



/*

 * smp_call_function_any - Run a function on any of the given cpus

 * @mask: The mask of cpus it can run on.

 * @func: The function to run. This must be fast and non-blocking.

 * @info: An arbitrary pointer to pass to the function.

 * @wait: If true, wait until function has completed.

 *

 * Returns 0 on success, else a negative status code (if no cpus were online).

 * Note that @wait will be implicitly turned on in case of allocation failures,

 * since we fall back to on-stack allocation.

 *

 * Selection preference:

 *	1) current cpu if in @mask

 *	2) any cpu of current node if in @mask

 *	3) any other online cpu in @mask

 */

int smp_call_function_any(const struct cpumask *mask,

			  void (*func)(void *info), void *info, int wait)

{

	unsigned int cpu;

	const struct cpumask *nodemask;

	int ret;



	/* Try for same CPU (cheapest) */

	cpu = get_cpu();

	if (cpumask_test_cpu(cpu, mask))

		goto call;



	/* Try for same node. */

	nodemask = cpumask_of_node(cpu);

	for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;

	     cpu = cpumask_next_and(cpu, nodemask, mask)) {

		if (cpu_online(cpu))

			goto call;

	}



	/* Any online will do: smp_call_function_single handles nr_cpu_ids. */

	cpu = cpumask_any_and(mask, cpu_online_mask);

call:

	ret = smp_call_function_single(cpu, func, info, wait);

	put_cpu();

	return ret;

}

EXPORT_SYMBOL_GPL(smp_call_function_any);



/**

 * __smp_call_function_single(): Run a function on another CPU

 * @cpu: The CPU to run on.

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