From 72f279b256d520e321a850880d094bc0bcbf45d6 Mon Sep 17 00:00:00 2001 From: Sheng Yang Date: Thu, 22 Oct 2009 19:19:34 +0800 Subject: generic-ipi: Fix misleading smp_call_function*() description After commit:8969a5ede0f9e17da4b943712429aef2c9bcd82b "generic-ipi: remove kmalloc()", wait = 0 can be guaranteed. Signed-off-by: Sheng Yang Cc: Peter Zijlstra Cc: Jens Axboe Cc: Nick Piggin LKML-Reference: <1256210374-25354-1-git-send-email-sheng@linux.intel.com> Signed-off-by: Ingo Molnar --- kernel/smp.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/kernel/smp.c b/kernel/smp.c index c9d1c7835c2..8bd618f0364 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -265,9 +265,7 @@ static DEFINE_PER_CPU(struct call_single_data, csd_data); * @info: An arbitrary pointer to pass to the function. * @wait: If true, wait until function has completed on other CPUs. * - * Returns 0 on success, else a negative status code. Note that @wait - * will be implicitly turned on in case of allocation failures, since - * we fall back to on-stack allocation. + * Returns 0 on success, else a negative status code. */ int smp_call_function_single(int cpu, void (*func) (void *info), void *info, int wait) @@ -355,9 +353,7 @@ void __smp_call_function_single(int cpu, struct call_single_data *data, * @wait: If true, wait (atomically) until function has completed * on other CPUs. * - * If @wait is true, then returns once @func has returned. Note that @wait - * will be implicitly turned on in case of allocation failures, since - * we fall back to on-stack allocation. + * If @wait is true, then returns once @func has returned. * * You must not call this function with disabled interrupts or from a * hardware interrupt handler or from a bottom half handler. Preemption @@ -443,8 +439,7 @@ EXPORT_SYMBOL(smp_call_function_many); * Returns 0. * * If @wait is true, then returns once @func has returned; otherwise - * it returns just before the target cpu calls @func. In case of allocation - * failure, @wait will be implicitly turned on. + * it returns just before the target cpu calls @func. * * You must not call this function with disabled interrupts or from a * hardware interrupt handler or from a bottom half handler. -- cgit v1.2.3 From 2ea6dec4a22a6f66f6633876212fd4d195cf8277 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Tue, 17 Nov 2009 14:27:27 -0800 Subject: 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: Rusty Russell Cc: Ingo Molnar Cc: Venkatesh Pallipadi Cc: Len Brown Cc: Zhao Yakui Cc: Dave Jones Cc: Thomas Gleixner Cc: Mike Galbraith Cc: "Zhang, Yanmin" Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- include/linux/smp.h | 11 ++++++++++- kernel/smp.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 55 insertions(+), 1 deletion(-) diff --git a/include/linux/smp.h b/include/linux/smp.h index 39c64bae776..7a0570e6a59 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -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 */ /* diff --git a/kernel/smp.c b/kernel/smp.c index 8bd618f0364..a8c76069cf5 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -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. -- cgit v1.2.3