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author | Manfred Spraul <manfred@colorfullife.com> | 2008-08-31 19:58:49 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-09-06 19:13:59 +0200 |
commit | 3ba35573ad9a149a3af19625b502679283382f6b (patch) | |
tree | 01e19ef5be3a247e310745c09134837b990dda77 /kernel/cpu.c | |
parent | 38736f475071b80b66be28af7b44c854073699cc (diff) | |
download | linux-stable-3ba35573ad9a149a3af19625b502679283382f6b.tar.gz linux-stable-3ba35573ad9a149a3af19625b502679283382f6b.tar.bz2 linux-stable-3ba35573ad9a149a3af19625b502679283382f6b.zip |
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')
-rw-r--r-- | kernel/cpu.c | 5 |
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. */ sched_idle_next(); |