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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 /kernel/cpu.c
parentc298be74492bece102f3379d14015638f1fd1fac (diff)
downloadlinux-2.6.34-ux500-9ea09af3bd3090e8349ca2899ca2011bd94cda85.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 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 47fff3b63cb..30e74dd6d01 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -269,8 +269,11 @@ out_release:
int __ref cpu_down(unsigned int cpu)
{
- int err = 0;
+ int err;
+ err = stop_machine_create();
+ if (err)
+ return err;
cpu_maps_update_begin();
if (cpu_hotplug_disabled) {
@@ -297,6 +300,7 @@ int __ref cpu_down(unsigned int cpu)
out:
cpu_maps_update_done();
+ stop_machine_destroy();
return err;
}
EXPORT_SYMBOL(cpu_down);