diff options
| author | Akinobu Mita <akinobu.mita@gmail.com> | 2007-10-18 03:05:12 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-18 14:37:21 -0700 |
| commit | a0d8cdb652d35af9319a9e0fb7134de2a276c636 (patch) | |
| tree | 485219f5bec58c9c6abba9e63e558c2a70b8755e | |
| parent | 12d00f6a121877235a5cacc56386936dd9bb81af (diff) | |
cpu hotplug: cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_PREPARE
The functions in a CPU notifier chain is called with CPU_UP_PREPARE event
before making the CPU online. If one of the callback returns NOTIFY_BAD, it
stops to deliver CPU_UP_PREPARE event, and CPU online operation is canceled.
Then CPU_UP_CANCELED event is delivered to the functions in a CPU notifier
chain again.
This CPU_UP_CANCELED event is delivered to the functions which have been
called with CPU_UP_PREPARE, not delivered to the functions which haven't been
called with CPU_UP_PREPARE.
The problem that makes existing cpu hotplug error handlings complex is that
the CPU_UP_CANCELED event is delivered to the function that has returned
NOTIFY_BAD, too.
Usually we don't expect to call destructor function against the object that
has failed to initialize. It is like:
err = register_something();
if (err) {
unregister_something();
return err;
}
So it is natural to deliver CPU_UP_CANCELED event only to the functions that
have returned NOTIFY_OK with CPU_UP_PREPARE event and not to call the function
that have returned NOTIFY_BAD. This is what this patch is doing.
Otherwise, every cpu hotplug notifiler has to track whether notifiler event is
failed or not for each cpu. (drivers/base/topology.c is doing this with
topology_dev_map)
Similary this patch makes same thing with CPU_DOWN_PREPARE and CPU_DOWN_FAILED
evnets.
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/cpu.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 38033db8d8ec..a21f71af9d81 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -150,6 +150,7 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen) err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls); if (err == NOTIFY_BAD) { + nr_calls--; __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL); printk("%s: attempt to take down CPU %u failed\n", @@ -233,6 +234,7 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen) ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls); if (ret == NOTIFY_BAD) { + nr_calls--; printk("%s: attempt to bring up CPU %u failed\n", __FUNCTION__, cpu); ret = -EINVAL; |