Linus,
please pull the latest smp-urgent-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
smp-urgent-for-linus
Two fixes for the hotplug state machine code:
- Move the misplaces smb() in the hotplug thread function to the proper
place, otherwise a half update control struct could be observed
- Prevent state corruption on error rollback, which causes the state to
advance by one and as a consequence skip it in the bringup sequence.
Thanks,
tglx
------------------>
Neeraj Upadhyay (1):
cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun()
Thomas Gleixner (1):
cpu/hotplug: Prevent state corruption on error rollback
kernel/cpu.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index aa7fe85ad62e..0097acec1c71 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -607,15 +607,15 @@ static void cpuhp_thread_fun(unsigned int cpu)
bool bringup = st->bringup;
enum cpuhp_state state;
+ if (WARN_ON_ONCE(!st->should_run))
+ return;
+
/*
* ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures
* that if we see ->should_run we also see the rest of the state.
*/
smp_mb();
- if (WARN_ON_ONCE(!st->should_run))
- return;
-
cpuhp_lock_acquire(bringup);
if (st->single) {
@@ -916,7 +916,8 @@ static int cpuhp_down_callbacks(unsigned int cpu, struct
cpuhp_cpu_state *st,
ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
if (ret) {
st->target = prev_state;
- undo_cpu_down(cpu, st);
+ if (st->state < prev_state)
+ undo_cpu_down(cpu, st);
break;
}
}
@@ -969,7 +970,7 @@ static int __ref _cpu_down(unsigned int cpu, int
tasks_frozen,
* to do the further cleanups.
*/
ret = cpuhp_down_callbacks(cpu, st, target);
- if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) {
+ if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) {
cpuhp_reset_state(st, prev_state);
__cpuhp_kick_ap(st);
}
