Merge branch 'core-ipi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-ipi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  generic-ipi: Add smp_call_function_any()
  generic-ipi: Fix misleading smp_call_function*() description

2 files changed, 58 insertions, 9 deletions

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 39c64bae776d..7a0570e6a596 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 c9d1c7835c2f..a8c76069cf50 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)
@@ -321,6 +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.
@@ -355,9 +398,7 @@ 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 +484,7 @@ 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.