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authorOleg Nesterov <oleg@redhat.com>2015-11-15 20:33:14 +0100
committerIngo Molnar <mingo@kernel.org>2015-11-23 09:48:18 +0100
commit6a19005157c464b47b2082f2617d12bc11198a0d (patch)
tree90b75567427d005de8b2032fe2005cd08153f40c
parent64038f292a1b33c7d46bd11f62f7798101152c00 (diff)
stop_machine: Don't disable preemption in stop_two_cpus()
Now that stop_two_cpus() path does not check cpu_active() we can remove preempt_disable(), it was only needed to ensure that stop_machine() can not be called after we observe cpu_active() == T and before we queue the new work. Also, turn the pointless and confusing ->executed check into WARN_ON(). We know that both works must be executed, otherwise we have a bug. And in fact I think that done->executed should die, see the next changes. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Milos Vyletel <milos@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20151115193314.GA8249@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/stop_machine.c11
1 files changed, 3 insertions, 8 deletions
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 1a66a9569915..17f01a9dc3df 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -258,7 +258,6 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
struct cpu_stop_work work1, work2;
struct multi_stop_data msdata;
- preempt_disable();
msdata = (struct multi_stop_data){
.fn = fn,
.data = arg,
@@ -277,16 +276,12 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
if (cpu1 > cpu2)
swap(cpu1, cpu2);
- if (cpu_stop_queue_two_works(cpu1, &work1, cpu2, &work2)) {
- preempt_enable();
+ if (cpu_stop_queue_two_works(cpu1, &work1, cpu2, &work2))
return -ENOENT;
- }
-
- preempt_enable();
wait_for_completion(&done.completion);
-
- return done.executed ? done.ret : -ENOENT;
+ WARN_ON(!done.executed);
+ return done.ret;
}
/**