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authorAkinobu Mita <akinobu.mita@gmail.com>2007-10-18 03:05:12 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-18 14:37:21 -0700
commita0d8cdb652d35af9319a9e0fb7134de2a276c636 (patch)
tree485219f5bec58c9c6abba9e63e558c2a70b8755e
parent12d00f6a121877235a5cacc56386936dd9bb81af (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.c2
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;