powerpc: Make sysfs code use smp_call_function_single

Impact: performance improvement

This fixes 'powerpc: avoid cpumask games in arch/powerpc/kernel/sysfs.c'
which talked about using smp_call_function_single, but actually used
work_on_cpu (an older version of the patch).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 6 insertions, 25 deletions

diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index 4a2ee08af6a7..e6cd6c990c25 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -134,36 +134,16 @@ void ppc_enable_pmcs(void)
 }
 EXPORT_SYMBOL(ppc_enable_pmcs);
 
-#if defined(CONFIG_6xx) || defined(CONFIG_PPC64)
-/* XXX convert to rusty's on_one_cpu */
-static unsigned long run_on_cpu(unsigned long cpu,
-                                unsigned long (*func)(unsigned long),
-                                unsigned long arg)
-{
-        cpumask_t old_affinity = current->cpus_allowed;
-        unsigned long ret;
-
-        /* should return -EINVAL to userspace */
-        if (set_cpus_allowed(current, cpumask_of_cpu(cpu)))
-                return 0;
-
-        ret = func(arg);
-
-        set_cpus_allowed(current, old_affinity);
-
-        return ret;
-}
-#endif
 
 #define SYSFS_PMCSETUP(NAME, ADDRESS) \
-static unsigned long read_##NAME(unsigned long junk) \
+static void read_##NAME(void *val) \
 { \
-        return mfspr(ADDRESS); \
+        mtspr(ADDRESS, *(unsigned long *)val);  \
 } \
 static unsigned long write_##NAME(unsigned long val) \
 { \
         ppc_enable_pmcs(); \
-        mtspr(ADDRESS, val); \
+        mtspr(ADDRESS, *(unsigned long *)val);  \
         return 0; \
 } \
 static ssize_t show_##NAME(struct sys_device *dev, \
@@ -171,7 +151,8 @@ static ssize_t show_##NAME(struct sys_device *dev, \
                         char *buf) \
 { \
         struct cpu *cpu = container_of(dev, struct cpu, sysdev); \
-        unsigned long val = run_on_cpu(cpu->sysdev.id, read_##NAME, 0); \
+        unsigned long val; \
+        smp_call_function_single(cpu->sysdev.id, read_##NAME, &val, 1); \
         return sprintf(buf, "%lx\n", val); \
 } \
 static ssize_t __used \
@@ -183,7 +164,7 @@ static ssize_t __used \
         int ret = sscanf(buf, "%lx", &val); \
         if (ret != 1) \
                 return -EINVAL; \
-        run_on_cpu(cpu->sysdev.id, write_##NAME, val); \
+        smp_call_function_single(cpu->sysdev.id, write_##NAME, &val, 1); \
         return count; \
 }