4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Zijlstra peterz@infradead.org
commit 1098582a0f6c4e8fd28da0a6305f9233d02c9c1d upstream.
Lots of things take locks, due to a wee bug, rcu_lockdep didn't notice that the locking tracepoints were using RCU.
Push rcu_idle_{enter,exit}() as deep as possible into the idle paths, this also resolves a lot of _rcuidle()/RCU_NONIDLE() usage.
Specifically, sched_clock_idle_wakeup_event() will use ktime which will use seqlocks which will tickle lockdep, and stop_critical_timings() uses lock.
Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Steven Rostedt (VMware) rostedt@goodmis.org Reviewed-by: Thomas Gleixner tglx@linutronix.de Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Tested-by: Marco Elver elver@google.com Link: https://lkml.kernel.org/r/20200821085348.310943801@infradead.org Tested-by: Linux Kernel Functional Testing lkft@linaro.org Tested-by: Naresh Kamboju naresh.kamboju@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/cpuidle/cpuidle.c | 12 ++++++++---- kernel/sched/idle.c | 22 ++++++++-------------- 2 files changed, 16 insertions(+), 18 deletions(-)
--- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -140,13 +140,14 @@ static void enter_s2idle_proper(struct c * executing it contains RCU usage regarded as invalid in the idle * context, so tell RCU about that. */ - RCU_NONIDLE(tick_freeze()); + tick_freeze(); /* * The state used here cannot be a "coupled" one, because the "coupled" * cpuidle mechanism enables interrupts and doing that with timekeeping * suspended is generally unsafe. */ stop_critical_timings(); + rcu_idle_enter(); drv->states[index].enter_s2idle(dev, drv, index); if (WARN_ON_ONCE(!irqs_disabled())) local_irq_disable(); @@ -155,7 +156,8 @@ static void enter_s2idle_proper(struct c * first CPU executing it calls functions containing RCU read-side * critical sections, so tell RCU about that. */ - RCU_NONIDLE(tick_unfreeze()); + rcu_idle_exit(); + tick_unfreeze(); start_critical_timings();
time_end = ns_to_ktime(local_clock()); @@ -224,16 +226,18 @@ int cpuidle_enter_state(struct cpuidle_d /* Take note of the planned idle state. */ sched_idle_set_state(target_state);
- trace_cpu_idle_rcuidle(index, dev->cpu); + trace_cpu_idle(index, dev->cpu); time_start = ns_to_ktime(local_clock());
stop_critical_timings(); + rcu_idle_enter(); entered_state = target_state->enter(dev, drv, index); + rcu_idle_exit(); start_critical_timings();
sched_clock_idle_wakeup_event(); time_end = ns_to_ktime(local_clock()); - trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); + trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
/* The cpu is no longer idle or about to enter idle. */ sched_idle_set_state(NULL); --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -53,17 +53,18 @@ __setup("hlt", cpu_idle_nopoll_setup);
static noinline int __cpuidle cpu_idle_poll(void) { + trace_cpu_idle(0, smp_processor_id()); + stop_critical_timings(); rcu_idle_enter(); - trace_cpu_idle_rcuidle(0, smp_processor_id()); local_irq_enable(); - stop_critical_timings();
while (!tif_need_resched() && - (cpu_idle_force_poll || tick_check_broadcast_expired())) + (cpu_idle_force_poll || tick_check_broadcast_expired())) cpu_relax(); - start_critical_timings(); - trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); + rcu_idle_exit(); + start_critical_timings(); + trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
return 1; } @@ -90,7 +91,9 @@ void __cpuidle default_idle_call(void) local_irq_enable(); } else { stop_critical_timings(); + rcu_idle_enter(); arch_cpu_idle(); + rcu_idle_exit(); start_critical_timings(); } } @@ -148,7 +151,6 @@ static void cpuidle_idle_call(void)
if (cpuidle_not_available(drv, dev)) { tick_nohz_idle_stop_tick(); - rcu_idle_enter();
default_idle_call(); goto exit_idle; @@ -166,19 +168,15 @@ static void cpuidle_idle_call(void)
if (idle_should_enter_s2idle() || dev->use_deepest_state) { if (idle_should_enter_s2idle()) { - rcu_idle_enter();
entered_state = cpuidle_enter_s2idle(drv, dev); if (entered_state > 0) { local_irq_enable(); goto exit_idle; } - - rcu_idle_exit(); }
tick_nohz_idle_stop_tick(); - rcu_idle_enter();
next_state = cpuidle_find_deepest_state(drv, dev); call_cpuidle(drv, dev, next_state); @@ -195,8 +193,6 @@ static void cpuidle_idle_call(void) else tick_nohz_idle_retain_tick();
- rcu_idle_enter(); - entered_state = call_cpuidle(drv, dev, next_state); /* * Give the governor an opportunity to reflect on the outcome @@ -212,8 +208,6 @@ exit_idle: */ if (WARN_ON_ONCE(irqs_disabled())) local_irq_enable(); - - rcu_idle_exit(); }
/*