cpu: Remove incorrect BUG_ON

Oleg mentioned that there is no actual guarantee the dying cpu's
migration thread is actually finished running when we get there, so
replace the BUG_ON() with a spinloop waiting for it.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2010-11-19 20:37:53 +01:00 committed by Ingo Molnar
parent 2e01f4740a
commit 51a96c7781
1 changed files with 4 additions and 1 deletions

View File

@ -249,8 +249,11 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
* The migration_call() CPU_DYING callback will have removed all
* runnable tasks from the cpu, there's only the idle task left now
* that the migration thread is done doing the stop_machine thing.
*
* Wait for the stop thread to go away.
*/
BUG_ON(!idle_cpu(cpu));
while (!idle_cpu(cpu))
cpu_relax();
/* This actually kills the CPU. */
__cpu_die(cpu);