The following commit has been merged into the sched/core branch of tip:
Commit-ID: 2ea46c6fc9452ac100ad907b051d797225847e33
Gitweb: https://git.kernel.org/tip/2ea46c6fc9452ac100ad907b051d797225847e33
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Tue, 20 Apr 2021 20:04:19 +02:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 21 Apr 2021 13:55:43 +02:00
cpumask/hotplug: Fix cpu_dying() state tracking
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@xxxxxxx>
Suggested-by: Vincent Donnefort <vincent.donnefort@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Vincent Donnefort <vincent.donnefort@xxxxxxx>
Reviewed-by: Valentin Schneider <valentin.schneider@xxxxxxx>
Link: https://lkml.kernel.org/r/YH7r+AoQEReSvxBI@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
---
kernel/cpu.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 838dcf2..e538518 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -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)
|