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authorThomas Gleixner <tglx@linutronix.de>2017-05-24 10:15:43 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-05-26 10:10:48 +0200
commit49dfe2a6779717d9c18395684ee31bdc98b22e53 (patch)
treed8a067fdbef6e58d980d3137c7fa6f8a27d212ea /kernel/cpu.c
parent0266d81e9bf5cc1fe6405c0523dfa015fe55aae1 (diff)
downloadlinux-49dfe2a6779717d9c18395684ee31bdc98b22e53.tar.bz2
cpuhotplug: Link lock stacks for hotplug callbacks
The CPU hotplug callbacks are not covered by lockdep versus the cpu hotplug rwsem. CPU0 CPU1 cpuhp_setup_state(STATE, startup, teardown); cpus_read_lock(); invoke_callback_on_ap(); kick_hotplug_thread(ap); wait_for_completion(); hotplug_thread_fn() lock(m); do_stuff(); unlock(m); Lockdep does not know about this dependency and will not trigger on the following code sequence: lock(m); cpus_read_lock(); Add a lockdep map and connect the initiators lock chain with the hotplug thread lock chain, so potential deadlocks can be detected. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20170524081549.709375845@linutronix.de
Diffstat (limited to 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 66836216ebae..7435ffc6163b 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -66,6 +66,12 @@ 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);
+#endif
+
/**
* cpuhp_step - Hotplug state machine step
* @name: Name of the step
@@ -403,6 +409,7 @@ static void cpuhp_thread_fun(unsigned int cpu)
st->should_run = false;
+ lock_map_acquire(&cpuhp_state_lock_map);
/* Single callback invocation for [un]install ? */
if (st->single) {
if (st->cb_state < CPUHP_AP_ONLINE) {
@@ -429,6 +436,7 @@ static void cpuhp_thread_fun(unsigned int cpu)
else if (st->state > st->target)
ret = cpuhp_ap_offline(cpu, st);
}
+ lock_map_release(&cpuhp_state_lock_map);
st->result = ret;
complete(&st->done);
}
@@ -443,6 +451,9 @@ 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);
+
/*
* If we are up and running, use the hotplug thread. For early calls
* we invoke the thread function directly.
@@ -486,6 +497,8 @@ static int cpuhp_kick_ap_work(unsigned int cpu)
enum cpuhp_state state = st->state;
trace_cpuhp_enter(cpu, st->target, state, cpuhp_kick_ap_work);
+ lock_map_acquire(&cpuhp_state_lock_map);
+ lock_map_release(&cpuhp_state_lock_map);
__cpuhp_kick_ap_work(st);
wait_for_completion(&st->done);
trace_cpuhp_exit(cpu, st->state, state, st->result);