diff options
| author | Xiaotian Feng <dfeng@redhat.com> | 2009-12-16 18:04:32 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-09-20 13:18:00 -0700 |
| commit | 4ec349b128a038e9011b56843ee86e44e356987e (patch) | |
| tree | aa6fa8be3af88a449d03ff9851010746cd8f823e /kernel | |
| parent | 62d4f155288b1c3524a6493341bc80d98dce11c5 (diff) | |
sched: Fix set_cpu_active() in cpu_down()
commit 9ee349ad6d326df3633d43f54202427295999c47 upstream
Sachin found cpu hotplug test failures on powerpc, which made
the kernel hang on his POWER box.
The problem is that we fail to re-activate a cpu when a
hot-unplug fails. Fix this by moving the de-activation into
_cpu_down after doing the initial checks.
Remove the synchronize_sched() calls and rely on those implied
by rebuilding the sched domains using the new mask.
Reported-by: Sachin Sant <sachinp@in.ibm.com>
Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Tested-by: Sachin Sant <sachinp@in.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091216170517.500272612@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cpu.c | 24 |
1 files changed, 3 insertions, 21 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 291ac586f37..1c8ddd6ee94 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -209,6 +209,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) return -ENOMEM; cpu_hotplug_begin(); + set_cpu_active(cpu, false); err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls); if (err == NOTIFY_BAD) { @@ -280,18 +281,6 @@ int __ref cpu_down(unsigned int cpu) goto out; } - set_cpu_active(cpu, false); - - /* - * Make sure the all cpus did the reschedule and are not - * using stale version of the cpu_active_mask. - * This is not strictly necessary becuase stop_machine() - * that we run down the line already provides the required - * synchronization. But it's really a side effect and we do not - * want to depend on the innards of the stop_machine here. - */ - synchronize_sched(); - err = _cpu_down(cpu, 0); out: @@ -382,19 +371,12 @@ int disable_nonboot_cpus(void) return error; cpu_maps_update_begin(); first_cpu = cpumask_first(cpu_online_mask); - /* We take down all of the non-boot CPUs in one shot to avoid races + /* + * We take down all of the non-boot CPUs in one shot to avoid races * with the userspace trying to use the CPU hotplug at the same time */ cpumask_clear(frozen_cpus); - for_each_online_cpu(cpu) { - if (cpu == first_cpu) - continue; - set_cpu_active(cpu, false); - } - - synchronize_sched(); - printk("Disabling non-boot CPUs ...\n"); for_each_online_cpu(cpu) { if (cpu == first_cpu) |