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smp_call_function_single(): be slightly less stupid 

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>
This commit is contained in:
Andrew Morton 2009-01-09 12:27:08 -08:00 committed by Ingo Molnar
parent abede81c4f
commit 53ce3d9564
3 changed files with 26 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
include/linux/smp.h
View 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) \

6
kernel/Makefile
View 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

18
kernel/up.c Normal file
View File

@ -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);