From: Heiko Carstens

If only one cpu is online we might as well use the non-smp variant of
stop_machine which should be much faster since no scheduling is needed.

Signed-off-by: Heiko Carstens
---
include/linux/stop_machine.h | 16 +++++++++++-----
kernel/stop_machine.c | 3 +++
2 files changed, 14 insertions(+), 5 deletions(-)

Index: linux-2.6/include/linux/stop_machine.h
================================================== =================
--- linux-2.6.orig/include/linux/stop_machine.h
+++ linux-2.6/include/linux/stop_machine.h
@@ -8,6 +8,16 @@
#include
#include

+static inline int stop_machine_simple(int (*fn)(void *), void *data,
+ const cpumask_t *cpus)
+{
+ int ret;
+ local_irq_disable();
+ ret = fn(data);
+ local_irq_enable();
+ return ret;
+}
+
#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)

/**
@@ -40,11 +50,7 @@ int __stop_machine(int (*fn)(void *), vo
static inline int stop_machine(int (*fn)(void *), void *data,
const cpumask_t *cpus)
{
- int ret;
- local_irq_disable();
- ret = fn(data);
- local_irq_enable();
- return ret;
+ return stop_machine_simple(fn, data, cpus);
}
#endif /* CONFIG_SMP */
#endif /* _LINUX_STOP_MACHINE */
Index: linux-2.6/kernel/stop_machine.c
================================================== =================
--- linux-2.6.orig/kernel/stop_machine.c
+++ linux-2.6/kernel/stop_machine.c
@@ -111,6 +111,9 @@ int __stop_machine(int (*fn)(void *), vo
struct work_struct *sm_work;
int i;

+ if (num_online_cpus() == 1)
+ return stop_machine_simple(fn, data, cpus);
+
/* Set up initial state. */
mutex_lock(&lock);
num_threads = num_online_cpus();

--
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