From 2ea46c6fc9452ac100ad907b051d797225847e33 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 20 Apr 2021 20:04:19 +0200 Subject: 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 Suggested-by: Vincent Donnefort Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Vincent Donnefort Reviewed-by: Valentin Schneider Link: https://lkml.kernel.org/r/YH7r+AoQEReSvxBI@hirez.programming.kicks-ass.net --- kernel/cpu.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/cpu.c b/kernel/cpu.c index 838dcf238f92..e538518556f4 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) -- cgit v1.2.3-59-g8ed1b