Commit-ID: 5f4b55e10645b7371322c800a5ec745cab487a6c
Gitweb: http://git.kernel.org/tip/5f4b55e10645b7371322c800a5ec745cab487a6c
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 20 Sep 2017 19:00:20 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 25 Sep 2017 22:11:43 +0200
smp/hotplug: Differentiate the AP-work lockdep class 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.
CPU0 CPU1 CPU2
cpuhp_up_callbacks: takedown_cpu: cpuhp_thread_fun:
cpuhp_state
irq_lock_sparse()
irq_lock_sparse()
wait_for_completion()
cpuhp_state
complete()
Now that we have consistent AP state, we can trivially separate the
AP-work class between up and down using st->bringup.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: max.byungchul.park@xxxxxxxxx
Cc: bigeasy@xxxxxxxxxxxxx
Cc: efault@xxxxxx
Cc: rostedt@xxxxxxxxxxx
Link: https://lkml.kernel.org/r/20170920170546.922524234@xxxxxxxxxxxxx
---
kernel/cpu.c | 41 ++++++++++++++++++++++++++++++++---------
1 file changed, 32 insertions(+), 9 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index d6f1b8c..d5c0998 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -68,9 +68,26 @@ struct cpuhp_cpu_state {
static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state);
#if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP)
-static struct lock_class_key cpuhp_state_key;
-static struct lockdep_map cpuhp_state_lock_map =
- STATIC_LOCKDEP_MAP_INIT("cpuhp_state", &cpuhp_state_key);
+static struct lockdep_map cpuhp_state_up_map =
+ STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map);
+static struct lockdep_map cpuhp_state_down_map =
+ STATIC_LOCKDEP_MAP_INIT("cpuhp_state-down", &cpuhp_state_down_map);
+
+
+static void inline cpuhp_lock_acquire(bool bringup)
+{
+ lock_map_acquire(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map);
+}
+
+static void inline cpuhp_lock_release(bool bringup)
+{
+ lock_map_release(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map);
+}
+#else
+
+static void inline cpuhp_lock_acquire(bool bringup) { }
+static void inline cpuhp_lock_release(bool bringup) { }
+
#endif
/**
@@ -486,7 +503,7 @@ static void cpuhp_thread_fun(unsigned int cpu)
if (WARN_ON_ONCE(!st->should_run))
return;
- lock_map_acquire(&cpuhp_state_lock_map);
+ cpuhp_lock_acquire(bringup);
if (st->single) {
state = st->cb_state;
@@ -537,7 +554,7 @@ static void cpuhp_thread_fun(unsigned int cpu)
}
next:
- lock_map_release(&cpuhp_state_lock_map);
+ cpuhp_lock_release(bringup);
if (!st->should_run)
complete(&st->done);
@@ -554,8 +571,11 @@ cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, bool bringup,
if (!cpu_online(cpu))
return 0;
- lock_map_acquire(&cpuhp_state_lock_map);
- lock_map_release(&cpuhp_state_lock_map);
+ cpuhp_lock_acquire(false);
+ cpuhp_lock_release(false);
+
+ cpuhp_lock_acquire(true);
+ cpuhp_lock_release(true);
/*
* If we are up and running, use the hotplug thread. For early calls
@@ -593,8 +613,11 @@ static int cpuhp_kick_ap_work(unsigned int cpu)
enum cpuhp_state prev_state = st->state;
int ret;
- lock_map_acquire(&cpuhp_state_lock_map);
- lock_map_release(&cpuhp_state_lock_map);
+ cpuhp_lock_acquire(false);
+ cpuhp_lock_release(false);
+
+ cpuhp_lock_acquire(true);
+ cpuhp_lock_release(true);
trace_cpuhp_enter(cpu, st->target, prev_state, cpuhp_kick_ap_work);
ret = cpuhp_kick_ap(st, st->target);
--
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