diff options
| -rw-r--r-- | include/trace/events/rcu.h | 1 | ||||
| -rw-r--r-- | kernel/rcutree_plugin.h | 24 |
2 files changed, 22 insertions, 3 deletions
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index aaa55e1b8c48..1480900c511c 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -292,6 +292,7 @@ TRACE_EVENT(rcu_dyntick, * "More callbacks": Still more callbacks, try again to clear them out. * "Callbacks drained": All callbacks processed, off to dyntick idle! * "Timer": Timer fired to cause CPU to continue processing callbacks. + * "Demigrate": Timer fired on wrong CPU, woke up correct CPU. * "Cleanup after idle": Idle exited, timer canceled. */ TRACE_EVENT(rcu_prep_idle, diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index d01e26df55a1..bbb43cad755e 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -2057,16 +2057,34 @@ static bool rcu_cpu_has_nonlazy_callbacks(int cpu) } /* + * Handler for smp_call_function_single(). The only point of this + * handler is to wake the CPU up, so the handler does only tracing. + */ +void rcu_idle_demigrate(void *unused) +{ + trace_rcu_prep_idle("Demigrate"); +} + +/* * Timer handler used to force CPU to start pushing its remaining RCU * callbacks in the case where it entered dyntick-idle mode with callbacks * pending. The hander doesn't really need to do anything because the * real work is done upon re-entry to idle, or by the next scheduling-clock * interrupt should idle not be re-entered. + * + * One special case: the timer gets migrated without awakening the CPU + * on which the timer was scheduled on. In this case, we must wake up + * that CPU. We do so with smp_call_function_single(). */ -static void rcu_idle_gp_timer_func(unsigned long unused) +static void rcu_idle_gp_timer_func(unsigned long cpu_in) { - WARN_ON_ONCE(1); /* Getting here can hang the system... */ + int cpu = (int)cpu_in; + trace_rcu_prep_idle("Timer"); + if (cpu != smp_processor_id()) + smp_call_function_single(cpu, rcu_idle_demigrate, NULL, 0); + else + WARN_ON_ONCE(1); /* Getting here can hang the system... */ } /* @@ -2075,7 +2093,7 @@ static void rcu_idle_gp_timer_func(unsigned long unused) static void rcu_prepare_for_idle_init(int cpu) { setup_timer(&per_cpu(rcu_idle_gp_timer, cpu), - rcu_idle_gp_timer_func, 0); + rcu_idle_gp_timer_func, cpu); } /* |