From: Heiko Carstens This makes cpu hotplug symmetrical: if CPU_UP_PREPARE fails we get CPU_UP_CANCELED, so we can undo what ever happened on PREPARE. The same should happen for CPU_DOWN_PREPARE. Cc: Srivatsa Vaddagiri Cc: Gautham Shenoy Signed-off-by: Heiko Carstens Cc: Oleg Nesterov Signed-off-by: Andrew Morton --- kernel/cpu.c | 17 +++++++++-------- 1 files changed, 9 insertions(+), 8 deletions(-) diff -puN kernel/cpu.c~call-cpu_chain-with-cpu_down_failed-if-cpu_down_prepare-failed kernel/cpu.c --- a/kernel/cpu.c~call-cpu_chain-with-cpu_down_failed-if-cpu_down_prepare-failed +++ a/kernel/cpu.c @@ -122,9 +122,10 @@ static int take_cpu_down(void *unused) /* Requires cpu_add_remove_lock to be held */ static int _cpu_down(unsigned int cpu) { - int err; + int err, nr_calls = 0; struct task_struct *p; cpumask_t old_allowed, tmp; + void *hcpu = (void *)(long)cpu; if (num_online_cpus() == 1) return -EBUSY; @@ -132,11 +133,12 @@ static int _cpu_down(unsigned int cpu) if (!cpu_online(cpu)) return -EINVAL; - raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, - (void *)(long)cpu); - err = raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE, - (void *)(long)cpu); + raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu); + err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE, + hcpu, -1, &nr_calls); if (err == NOTIFY_BAD) { + __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED, hcpu, + nr_calls, NULL); printk("%s: attempt to take down CPU %u failed\n", __FUNCTION__, cpu); err = -EINVAL; @@ -156,7 +158,7 @@ static int _cpu_down(unsigned int cpu) if (IS_ERR(p) || cpu_online(cpu)) { /* CPU didn't die: tell everyone. Can't complain. */ if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED, - (void *)(long)cpu) == NOTIFY_BAD) + hcpu) == NOTIFY_BAD) BUG(); if (IS_ERR(p)) { @@ -178,8 +180,7 @@ static int _cpu_down(unsigned int cpu) put_cpu(); /* CPU is completely dead: tell everyone. Too late to complain. */ - if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD, - (void *)(long)cpu) == NOTIFY_BAD) + if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD, hcpu) == NOTIFY_BAD) BUG(); check_for_tasks(cpu); _