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cpumask/hotplug: Fix cpu_dying() state tracking

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Vincent reported that for states with a NULL startup/teardown function
we do not call cpuhp_invoke_callback() (because there is none) and as
such we'll not update the cpu_dying() state.

The stale cpu_dying() can eventually lead to triggering BUG().

Rectify this by updating cpu_dying() in the exact same places the
hotplug machinery tracks its directional state, namely
cpuhp_set_state() and cpuhp_reset_state().

Reported-by: Vincent Donnefort <vincent.donnefort@arm.com>
Suggested-by: Vincent Donnefort <vincent.donnefort@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Donnefort <vincent.donnefort@arm.com>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/YH7r+AoQEReSvxBI@hirez.programming.kicks-ass.net
This commit is contained in:
Peter Zijlstra 2021-04-20 20:04:19 +02:00
parent 3a7956e25e
commit 2ea46c6fc9
1 changed files with 11 additions and 5 deletions
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16
kernel/cpu.c
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@ -63,6 +63,7 @@ struct cpuhp_cpu_state {
bool rollback;
bool single;
bool bringup;
int cpu;
struct hlist_node *node;
struct hlist_node *last;
enum cpuhp_state cb_state;
@ -160,9 +161,6 @@ static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
int (*cb)(unsigned int cpu);
int ret, cnt;
if (cpu_dying(cpu) != !bringup)
set_cpu_dying(cpu, !bringup);
if (st->fail == state) {
st->fail = CPUHP_INVALID;
return -EAGAIN;
@ -467,13 +465,16 @@ static inline enum cpuhp_state
cpuhp_set_state(struct cpuhp_cpu_state *st, enum cpuhp_state target)
{
enum cpuhp_state prev_state = st->state;
bool bringup = st->state < target;
st->rollback = false;
st->last = NULL;
st->target = target;
st->single = false;
st->bringup = st->state < target;
st->bringup = bringup;
if (cpu_dying(st->cpu) != !bringup)
set_cpu_dying(st->cpu, !bringup);
return prev_state;
}
@ -481,6 +482,8 @@ cpuhp_set_state(struct cpuhp_cpu_state *st, enum cpuhp_state target)
static inline void
cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state prev_state)
{
bool bringup = !st->bringup;
st->target = prev_state;
/*
@ -503,7 +506,9 @@ cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state prev_state)
st->state++;
}
st->bringup = !st->bringup;
st->bringup = bringup;
if (cpu_dying(st->cpu) != !bringup)
set_cpu_dying(st->cpu, !bringup);
}
/* Regular hotplug invocation of the AP hotplug thread */
@ -693,6 +698,7 @@ static void cpuhp_create(unsigned int cpu)
init_completion(&st->done_up);
init_completion(&st->done_down);
st->cpu = cpu;
}
static int cpuhp_should_run(unsigned int cpu)