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authorHeiko Carstens <heiko.carstens@de.ibm.com>2008-12-22 12:36:30 +0100
committerRusty Russell <rusty@rustcorp.com.au>2009-01-05 08:40:14 +1030
commit9ea09af3bd3090e8349ca2899ca2011bd94cda85 (patch)
tree36396347bb750a6aecb0771cfebf9887aaaae492 /include/linux/stop_machine.h
parentc298be74492bece102f3379d14015638f1fd1fac (diff)
downloadlinux-linaro-stable-9ea09af3bd3090e8349ca2899ca2011bd94cda85.tar.gz
stop_machine: introduce stop_machine_create/destroy.
Introduce stop_machine_create/destroy. With this interface subsystems that need a non-failing stop_machine environment can create the stop_machine machine threads before actually calling stop_machine. When the threads aren't needed anymore they can be killed with stop_machine_destroy again. When stop_machine gets called and the threads aren't present they will be created and destroyed automatically. This restores the old behaviour of stop_machine. This patch also converts cpu hotplug to the new interface since it is special: cpu_down calls __stop_machine instead of stop_machine. However the kstop threads will only be created when stop_machine gets called. Changing the code so that the threads would be created automatically on __stop_machine is currently not possible: when __stop_machine gets called we hold cpu_add_remove_lock, which is the same lock that create_rt_workqueue would take. So the workqueue needs to be created before the cpu hotplug code locks cpu_add_remove_lock. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'include/linux/stop_machine.h')
-rw-r--r--include/linux/stop_machine.h22
1 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h
index 74d59a641362..baba3a23a814 100644
--- a/include/linux/stop_machine.h
+++ b/include/linux/stop_machine.h
@@ -35,6 +35,24 @@ int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
* won't come or go while it's being called. Used by hotplug cpu.
*/
int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
+
+/**
+ * stop_machine_create: create all stop_machine threads
+ *
+ * Description: This causes all stop_machine threads to be created before
+ * stop_machine actually gets called. This can be used by subsystems that
+ * need a non failing stop_machine infrastructure.
+ */
+int stop_machine_create(void);
+
+/**
+ * stop_machine_destroy: destroy all stop_machine threads
+ *
+ * Description: This causes all stop_machine threads which were created with
+ * stop_machine_create to be destroyed again.
+ */
+void stop_machine_destroy(void);
+
#else
static inline int stop_machine(int (*fn)(void *), void *data,
@@ -46,5 +64,9 @@ static inline int stop_machine(int (*fn)(void *), void *data,
local_irq_enable();
return ret;
}
+
+static inline int stop_machine_create(void) { return 0; }
+static inline void stop_machine_destroy(void) { }
+
#endif /* CONFIG_SMP */
#endif /* _LINUX_STOP_MACHINE */