From: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
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.
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Zhao Yakui <yakui.zhao@xxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: "Zhang, Yanmin" <yanmin_zhang@xxxxxxxxxxxxxxx>
Cc: Jaswinder Singh Rajput <jaswinder@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/smp.h | 3 +++
kernel/smp.c | 40 ++++++++++++++++++++++++++++++++++++++++
kernel/up.c | 12 ++++++++++++
3 files changed, 55 insertions(+)
diff -puN include/linux/smp.h~kernel-core-add-smp_call_function_any include/linux/smp.h
--- a/include/linux/smp.h~kernel-core-add-smp_call_function_any
+++ a/include/linux/smp.h
@@ -27,6 +27,9 @@ extern unsigned int total_cpus;
int smp_call_function_single(int cpuid, void (*func) (void *info), void *info,
int wait);
+int smp_call_function_any(const struct cpumask *mask,
+ void (*func)(void *info), void *info, int wait);
+
#ifdef CONFIG_SMP
#include <linux/preempt.h>
diff -puN kernel/smp.c~kernel-core-add-smp_call_function_any kernel/smp.c
--- a/kernel/smp.c~kernel-core-add-smp_call_function_any
+++ a/kernel/smp.c
@@ -319,6 +319,46 @@ int smp_call_function_single(int cpu, vo
}
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.
+ */
+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.
diff -puN kernel/up.c~kernel-core-add-smp_call_function_any kernel/up.c
--- a/kernel/up.c~kernel-core-add-smp_call_function_any
+++ a/kernel/up.c
@@ -19,3 +19,15 @@ int smp_call_function_single(int cpu, vo
return 0;
}
EXPORT_SYMBOL(smp_call_function_single);
+
+int smp_call_function_any(const struct cpumask *mask,
+ void (*func)(void *info), void *info,
+ int wait)
+{
+ local_irq_disable();
+ (func)(info);
+ local_irq_enable();
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(smp_call_function_any);
_
--
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