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authorPeter Zijlstra <peterz@infradead.org>2017-09-20 19:00:19 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-09-25 22:11:43 +0200
commit5ebe7742fff8be5f1359bc50f5d43fb6ff7bd060 (patch)
tree7959e66651a79d2b7a3df00a1e93f391c2f0d0a7 /kernel
parent5f4b55e10645b7371322c800a5ec745cab487a6c (diff)
download96b-common-5ebe7742fff8be5f1359bc50f5d43fb6ff7bd060.tar.gz
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: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas 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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cpu.c49
1 files changed, 32 insertions, 17 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index d5c09985fbb6..6bbe261b851f 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -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 @@ err:
}
#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 @@ next:
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 */