path: root/kernel/cpu.c
diff options
authorManfred Spraul <manfred@colorfullife.com>2008-08-31 19:58:49 +0200
committerIngo Molnar <mingo@elte.hu>2008-09-06 19:13:59 +0200
commit3ba35573ad9a149a3af19625b502679283382f6b (patch)
tree01e19ef5be3a247e310745c09134837b990dda77 /kernel/cpu.c
parent38736f475071b80b66be28af7b44c854073699cc (diff)
kernel/cpu.c: Move the CPU_DYING notifiers
When a cpu is taken offline, the CPU_DYING notifiers are called on the dying cpu. According to <linux/notifiers.h>, the cpu should be "not running any task, not handling interrupts, soon dead". For the current implementation, this is not true: - __cpu_disable can fail. If it fails, then the cpu will remain alive and happy. - At least on x86, __cpu_disable() briefly enables the local interrupts to handle any outstanding interrupts. What about moving CPU_DYING down a few lines, behind the __cpu_disable() line? There are only two CPU_DYING handlers in the kernel right now: one in kvm, one in the scheduler. Both should work with the patch applied [and: I'm not sure if either one handles a failing __cpu_disable()] The patch survives simple offlining a cpu. kvm untested due to lack of a test setup. Signed-off-By: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/cpu.c')
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index f17e9854c246..9e7ebde1331c 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -199,13 +199,14 @@ static int __ref take_cpu_down(void *_param)
struct take_cpu_down_param *param = _param;
int err;
- raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
- param->hcpu);
/* Ensure this CPU doesn't handle any more interrupts. */
err = __cpu_disable();
if (err < 0)
return err;
+ raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
+ param->hcpu);
/* Force idle task to run as soon as we yield: it should
immediately notice cpu is offline and die quickly. */

Privacy Policy