smp: add func to IPI cpus based on parameter func

Add the on_each_cpu_cond() function that wraps on_each_cpu_mask() and
calculates the cpumask of cpus to IPI by calling a function supplied as a
parameter in order to determine whether to IPI each specific cpu.

The function works around allocation failure of cpumask variable in
CONFIG_CPUMASK_OFFSTACK=y by itereating over cpus sending an IPI a time
via smp_call_function_single().

The function is useful since it allows to seperate the specific code that
decided in each case whether to IPI a specific cpu for a specific request
from the common boilerplate code of handling creating the mask, handling
failures etc.

[[email protected]: s/gfpflags/gfp_flags/]
[[email protected]: avoid double-evaluation of `info' (per Michal), parenthesise evaluation of `cond_func']
[[email protected]: s/CPU/CPUs, use all 80 cols in comment]
Signed-off-by: Gilad Ben-Yossef <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Christoph Lameter <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Russell King <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Matt Mackall <[email protected]>
Cc: Sasha Levin <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Avi Kivity <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Cc: Kosaki Motohiro <[email protected]>
Cc: Milton Miller <[email protected]>
Reviewed-by: "Srivatsa S. Bhat" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 24 insertions, 0 deletions

diff --git a/include/linux/smp.h b/include/linux/smp.h
index d0adb7898d54..10530d92c04b 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -109,6 +109,15 @@ void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
 		void *info, bool wait);
 
 /*
+ * Call a function on each processor for which the supplied function
+ * cond_func returns a positive value. This may include the local
+ * processor.
+ */
+void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
+		smp_call_func_t func, void *info, bool wait,
+		gfp_t gfp_flags);
+
+/*
  * Mark the boot cpu "online" so that it can call console drivers in
  * printk() and can access its per-cpu storage.
  */
@@ -153,6 +162,21 @@ static inline int up_smp_call_function(smp_call_func_t func, void *info)
 			local_irq_enable();		\
 		}					\
 	} while (0)
+/*
+ * Preemption is disabled here to make sure the cond_func is called under the
+ * same condtions in UP and SMP.
+ */
+#define on_each_cpu_cond(cond_func, func, info, wait, gfp_flags)\
+	do {							\
+		void *__info = (info);				\
+		preempt_disable();				\
+		if ((cond_func)(0, __info)) {			\
+			local_irq_disable();			\
+			(func)(__info);				\
+			local_irq_enable();			\
+		}						\
+		preempt_enable();				\
+	} while (0)
 
 static inline void smp_send_reschedule(int cpu) { }
 #define num_booting_cpus()			1