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| author |   Peter Zijlstra <peterz@infradead.org> | 2013-09-17 09:30:55 +0200 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2013-09-25 13:53:08 +0200 |
| commit | b021fe3e25094fbec22d0eff846d2adeee1b9736 (patch) | |
| tree | 6193cc7952f980625e9f77c76f650fb2a7844071 | |
| parent | x86: Use asm goto to implement better modify_and_test() functions (diff) | |
| download | linux-dev-b021fe3e25094fbec22d0eff846d2adeee1b9736.tar.xz linux-dev-b021fe3e25094fbec22d0eff846d2adeee1b9736.zip | |
sched, rcu: Make RCU use resched_cpu()
We're going to deprecate and remove set_need_resched() for it will do
the wrong thing. Make an exception for RCU and allow it to use
resched_cpu() which will do the right thing.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-2eywnacjl1nllctl1nszqa5w@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/rcutree.c | 15 | ||||
| -rw-r--r-- | kernel/sched/core.c | 10 |
2 files changed, 16 insertions, 9 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 32618b3fe4e6..1dc9f3604ad8 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -898,6 +898,12 @@ static void print_other_cpu_stall(struct rcu_state *rsp) force_quiescent_state(rsp); /* Kick them all. */ } +/* + * This function really isn't for public consumption, but RCU is special in + * that context switches can allow the state machine to make progress. + */ +extern void resched_cpu(int cpu); + static void print_cpu_stall(struct rcu_state *rsp) { int cpu; @@ -927,7 +933,14 @@ static void print_cpu_stall(struct rcu_state *rsp) 3 * rcu_jiffies_till_stall_check() + 3; raw_spin_unlock_irqrestore(&rnp->lock, flags); - set_need_resched(); /* kick ourselves to get things going. */ + /* + * Attempt to revive the RCU machinery by forcing a context switch. + * + * A context switch would normally allow the RCU state machine to make + * progress and it could be we're stuck in kernel space without context + * switches for an entirely unreasonable amount of time. + */ + resched_cpu(smp_processor_id()); } static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index ac5796783c49..242da0c03aba 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -513,12 +513,11 @@ static inline void init_hrtick(void) * might also involve a cross-CPU call to trigger the scheduler on * the target CPU. */ -#ifdef CONFIG_SMP void resched_task(struct task_struct *p) { int cpu; - assert_raw_spin_locked(&task_rq(p)->lock); + lockdep_assert_held(&task_rq(p)->lock); if (test_tsk_need_resched(p)) return; @@ -546,6 +545,7 @@ void resched_cpu(int cpu) raw_spin_unlock_irqrestore(&rq->lock, flags); } +#ifdef CONFIG_SMP #ifdef CONFIG_NO_HZ_COMMON /* * In the semi idle case, use the nearest busy cpu for migrating timers @@ -693,12 +693,6 @@ void sched_avg_update(struct rq *rq) } } -#else /* !CONFIG_SMP */ -void resched_task(struct task_struct *p) -{ - assert_raw_spin_locked(&task_rq(p)->lock); - set_tsk_need_resched(p); -} #endif /* CONFIG_SMP */ #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ |