Commit 5ebe7742 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner

smp/hotplug: Differentiate the AP completion between up and down

With lockdep-crossrelease we get deadlock reports that span cpu-up and
cpu-down chains. Such deadlocks cannot possibly happen because cpu-up
and cpu-down are globally serialized.

  takedown_cpu()
    irq_lock_sparse()
    wait_for_completion(&st->done)

                                cpuhp_thread_fun
                                  cpuhp_up_callback
                                    cpuhp_invoke_callback
                                      irq_affinity_online_cpu
                                        irq_local_spare()
                                        irq_unlock_sparse()
                                  complete(&st->done)

Now that we have consistent AP state, we can trivially separate the
AP completion between up and down using st->bringup.
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: max.byungchul.park@gmail.com
Cc: bigeasy@linutronix.de
Cc: efault@gmx.de
Cc: rostedt@goodmis.org
Link: https://lkml.kernel.org/r/20170920170546.872472799@infradead.org
parent 5f4b55e1
......@@ -46,7 +46,8 @@
* @bringup: Single callback bringup or teardown selector
* @cb_state: The state for a single callback (install/uninstall)
* @result: Result of the operation
* @done: Signal completion to the issuer of the task
* @done_up: Signal completion to the issuer of the task for cpu-up
* @done_down: Signal completion to the issuer of the task for cpu-down
*/
struct cpuhp_cpu_state {
enum cpuhp_state state;
......@@ -61,7 +62,8 @@ struct cpuhp_cpu_state {
struct hlist_node *last;
enum cpuhp_state cb_state;
int result;
struct completion done;
struct completion done_up;
struct completion done_down;
#endif
};
......@@ -130,14 +132,6 @@ static bool cpuhp_is_ap_state(enum cpuhp_state state)
return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU;
}
/*
* The former STARTING/DYING states, ran with IRQs disabled and must not fail.
*/
static bool cpuhp_is_atomic_state(enum cpuhp_state state)
{
return CPUHP_AP_IDLE_DEAD <= state && state < CPUHP_AP_ONLINE;
}
static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
{
struct cpuhp_step *sp;
......@@ -232,6 +226,26 @@ static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
}
#ifdef CONFIG_SMP
static inline void wait_for_ap_thread(struct cpuhp_cpu_state *st, bool bringup)
{
struct completion *done = bringup ? &st->done_up : &st->done_down;
wait_for_completion(done);
}
static inline void complete_ap_thread(struct cpuhp_cpu_state *st, bool bringup)
{
struct completion *done = bringup ? &st->done_up : &st->done_down;
complete(done);
}
/*
* The former STARTING/DYING states, ran with IRQs disabled and must not fail.
*/
static bool cpuhp_is_atomic_state(enum cpuhp_state state)
{
return CPUHP_AP_IDLE_DEAD <= state && state < CPUHP_AP_ONLINE;
}
/* Serializes the updates to cpu_online_mask, cpu_present_mask */
static DEFINE_MUTEX(cpu_add_remove_lock);
bool cpuhp_tasks_frozen;
......@@ -368,7 +382,7 @@ static void __cpuhp_kick_ap(struct cpuhp_cpu_state *st)
smp_mb();
st->should_run = true;
wake_up_process(st->thread);
wait_for_completion(&st->done);
wait_for_ap_thread(st, st->bringup);
}
static int cpuhp_kick_ap(struct cpuhp_cpu_state *st, enum cpuhp_state target)
......@@ -391,7 +405,7 @@ static int bringup_wait_for_ap(unsigned int cpu)
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
/* Wait for the CPU to reach CPUHP_AP_ONLINE_IDLE */
wait_for_completion(&st->done);
wait_for_ap_thread(st, true);
if (WARN_ON_ONCE((!cpu_online(cpu))))
return -ECANCELED;
......@@ -464,7 +478,8 @@ static void cpuhp_create(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
init_completion(&st->done);
init_completion(&st->done_up);
init_completion(&st->done_down);
}
static int cpuhp_should_run(unsigned int cpu)
......@@ -557,7 +572,7 @@ static void cpuhp_thread_fun(unsigned int cpu)
cpuhp_lock_release(bringup);
if (!st->should_run)
complete(&st->done);
complete_ap_thread(st, bringup);
}
/* Invoke a single callback on a remote cpu */
......@@ -753,7 +768,7 @@ static int takedown_cpu(unsigned int cpu)
*
* Wait for the stop thread to go away.
*/
wait_for_completion(&st->done);
wait_for_ap_thread(st, false);
BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
/* Interrupts are moved away from the dying cpu, reenable alloc/free */
......@@ -772,7 +787,7 @@ static void cpuhp_complete_idle_dead(void *arg)
{
struct cpuhp_cpu_state *st = arg;
complete(&st->done);
complete_ap_thread(st, false);
}
void cpuhp_report_idle_dead(void)
......@@ -939,7 +954,7 @@ void cpuhp_online_idle(enum cpuhp_state state)
return;
st->state = CPUHP_AP_ONLINE_IDLE;
complete(&st->done);
complete_ap_thread(st, true);
}
/* Requires cpu_add_remove_lock to be held */
......
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