smp_call_function_single(): be slightly less stupid
Andrew Morton [Fri, 9 Jan 2009 20:27:08 +0000 (12:27 -0800)]
If you do

smp_call_function_single(expression-with-side-effects, ...)

then expression-with-side-effects never gets evaluated on UP builds.

As always, implementing it in C is the correct thing to do.

While we're there, uninline it for size and possible header dependency
reasons.

And create a new kernel/up.c, as a place in which to put
uniprocessor-specific code and storage.  It should mirror kernel/smp.c.

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/smp.h
kernel/Makefile
kernel/up.c [new file with mode: 0644]

index b824669..715196b 100644 (file)
@@ -24,6 +24,9 @@ struct call_single_data {
 /* total number of cpus in this system (may exceed NR_CPUS) */
 extern unsigned int total_cpus;
 
+int smp_call_function_single(int cpuid, void (*func) (void *info), void *info,
+                               int wait);
+
 #ifdef CONFIG_SMP
 
 #include <linux/preempt.h>
@@ -79,8 +82,6 @@ smp_call_function_mask(cpumask_t mask, void(*func)(void *info), void *info,
        return 0;
 }
 
-int smp_call_function_single(int cpuid, void (*func) (void *info), void *info,
-                               int wait);
 void __smp_call_function_single(int cpuid, struct call_single_data *data);
 
 /*
@@ -140,14 +141,6 @@ static inline int up_smp_call_function(void (*func)(void *), void *info)
 static inline void smp_send_reschedule(int cpu) { }
 #define num_booting_cpus()                     1
 #define smp_prepare_boot_cpu()                 do {} while (0)
-#define smp_call_function_single(cpuid, func, info, wait) \
-({ \
-       WARN_ON(cpuid != 0);    \
-       local_irq_disable();    \
-       (func)(info);           \
-       local_irq_enable();     \
-       0;                      \
-})
 #define smp_call_function_mask(mask, func, info, wait) \
                        (up_smp_call_function(func, info))
 #define smp_call_function_many(mask, func, info, wait) \
index 2921d90..2aebc4c 100644 (file)
@@ -40,7 +40,11 @@ obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
 obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
 obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o
 obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
-obj-$(CONFIG_USE_GENERIC_SMP_HELPERS) += smp.o
+ifeq ($(CONFIG_USE_GENERIC_SMP_HELPERS),y)
+obj-y += smp.o
+else
+obj-y += up.o
+endif
 obj-$(CONFIG_SMP) += spinlock.o
 obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
 obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
diff --git a/kernel/up.c b/kernel/up.c
new file mode 100644 (file)
index 0000000..ce62cc9
--- /dev/null
@@ -0,0 +1,18 @@
+/*
+ * Uniprocessor-only support functions.  The counterpart to kernel/smp.c
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/smp.h>
+
+int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
+                               int wait)
+{
+       WARN_ON(cpuid != 0);
+       local_irq_disable();
+       (func)(info);
+       local_irq_enable();
+       return 0;
+}
+EXPORT_SYMBOL(smp_call_function_single);