diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2009-07-03 18:16:38 (GMT) |
---|---|---|
committer | Scott Wood <scottwood@freescale.com> | 2015-02-13 22:20:39 (GMT) |
commit | c63d9c27c282777f892d282b3b0819ce58854f90 (patch) | |
tree | b89a49c689656f0d4a1894ac63bc1d2ee5cd1450 /kernel | |
parent | 1c9e58fad223741faa7dd6ceaaaf0b711ce07f96 (diff) | |
download | linux-fsl-qoriq-c63d9c27c282777f892d282b3b0819ce58854f90.tar.xz |
softirq: Sanitize softirq pending for NOHZ/RT
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/softirq.c | 63 | ||||
-rw-r--r-- | kernel/time/tick-sched.c | 9 |
2 files changed, 64 insertions, 8 deletions
diff --git a/kernel/softirq.c b/kernel/softirq.c index c647956..a1c156a 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -62,6 +62,69 @@ char *softirq_to_name[NR_SOFTIRQS] = { "TASKLET", "SCHED", "HRTIMER", "RCU" }; +#ifdef CONFIG_NO_HZ_COMMON +# ifdef CONFIG_PREEMPT_RT_FULL +/* + * On preempt-rt a softirq might be blocked on a lock. There might be + * no other runnable task on this CPU because the lock owner runs on + * some other CPU. So we have to go into idle with the pending bit + * set. Therefor we need to check this otherwise we warn about false + * positives which confuses users and defeats the whole purpose of + * this test. + * + * This code is called with interrupts disabled. + */ +void softirq_check_pending_idle(void) +{ + static int rate_limit; + u32 warnpending = 0, pending; + + if (rate_limit >= 10) + return; + + pending = local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK; + if (pending) { + struct task_struct *tsk; + + tsk = __get_cpu_var(ksoftirqd); + /* + * The wakeup code in rtmutex.c wakes up the task + * _before_ it sets pi_blocked_on to NULL under + * tsk->pi_lock. So we need to check for both: state + * and pi_blocked_on. + */ + raw_spin_lock(&tsk->pi_lock); + + if (!tsk->pi_blocked_on && !(tsk->state == TASK_RUNNING)) + warnpending = 1; + + raw_spin_unlock(&tsk->pi_lock); + } + + if (warnpending) { + printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n", + pending); + rate_limit++; + } +} +# else +/* + * On !PREEMPT_RT we just printk rate limited: + */ +void softirq_check_pending_idle(void) +{ + static int rate_limit; + + if (rate_limit < 10 && + (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { + printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n", + local_softirq_pending()); + rate_limit++; + } +} +# endif +#endif + /* * we cannot loop indefinitely here to avoid userspace starvation, * but we also don't want to introduce a worst case 1/HZ latency diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 0619d3d..fa4c28b 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -724,14 +724,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) return false; if (unlikely(local_softirq_pending() && cpu_online(cpu))) { - static int ratelimit; - - if (ratelimit < 10 && - (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { - pr_warn("NOHZ: local_softirq_pending %02x\n", - (unsigned int) local_softirq_pending()); - ratelimit++; - } + softirq_check_pending_idle(); return false; } |