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Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull cpu hotplug fixes from Thomas Gleixner:
 "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"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu/hotplug: Prevent state corruption on error rollback
  cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun()
This commit is contained in:
Linus Torvalds 2018-09-09 06:48:06 -07:00
parent 3243a89dcb 69fa6eb7d6
commit e0a0d05848
1 changed files with 6 additions and 5 deletions
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11
kernel/cpu.c
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@ -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);
}