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commit e0a0d05848401df48b10f3defce14a5670a0f9f6
parent 3243a89dcbd8f5810b72ee0903d349bd000c4c9d
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun,  9 Sep 2018 06:48:06 -0700

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()

Diffstat:
Mkernel/cpu.c | 11++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git 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); }