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authorXiaotian Feng <dfeng@redhat.com>2009-12-16 18:04:32 +0100
committerIngo Molnar <mingo@elte.hu>2009-12-16 19:01:53 +0100
commit9ee349ad6d326df3633d43f54202427295999c47 (patch)
tree06f4795cb1b3f493b2421b65af0fd870875c8168 /kernel/cpu.c
parent933b0618d8b2a59c7a0742e43836544e02f1e9bd (diff)
downloadlinux-2.6.34-ux500-9ee349ad6d326df3633d43f54202427295999c47.tar.gz
sched: Fix set_cpu_active() in cpu_down()
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>
Diffstat (limited to 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c24
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)