OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

softirq: Adapt NOHZ softirq pending check to new RT scheme 

We can't rely on ksoftirqd anymore and we need to check the tasks
which run a particular softirq and if such a task is pi blocked ignore
the other pending bits of that task as well.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2012-10-28 13:46:16 +00:00 committed by Alibek Omarov
parent d2f09d0ed6
commit e1bb862d7e
1 changed files with 58 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

83
kernel/softirq.c
View File

@ -65,46 +65,71 @@ const char * const softirq_to_name[NR_SOFTIRQS] = {
#ifdef CONFIG_NO_HZ_COMMON
# ifdef CONFIG_PREEMPT_RT_FULL
struct softirq_runner {
struct task_struct *runner[NR_SOFTIRQS];
};
static DEFINE_PER_CPU(struct softirq_runner, softirq_runners);
static inline void softirq_set_runner(unsigned int sirq)
{
struct softirq_runner *sr = &__get_cpu_var(softirq_runners);
sr->runner[sirq] = current;
}
static inline void softirq_clr_runner(unsigned int sirq)
{
struct softirq_runner *sr = &__get_cpu_var(softirq_runners);
sr->runner[sirq] = NULL;
}
/*
* 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.
* On preempt-rt a softirq running context 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;
struct softirq_runner *sr = &__get_cpu_var(softirq_runners);
u32 warnpending;
int i;
if (rate_limit >= 10)
return;
pending = local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK;
if (pending) {
struct task_struct *tsk;
warnpending = local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK;
for (i = 0; i < NR_SOFTIRQS; i++) {
struct task_struct *tsk = sr->runner[i];
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 (tsk) {
raw_spin_lock(&tsk->pi_lock);
if (tsk->pi_blocked_on || tsk->state == TASK_RUNNING) {
/* Clear all bits pending in that task */
warnpending &= ~(tsk->softirqs_raised);
warnpending &= ~(1 << i);
}
raw_spin_unlock(&tsk->pi_lock);
}
}
if (warnpending) {
printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
pending);
warnpending);
rate_limit++;
}
}
@ -124,6 +149,10 @@ void softirq_check_pending_idle(void)
}
}
# endif
#else /* !CONFIG_NO_HZ_COMMON */
static inline void softirq_set_runner(unsigned int sirq) { }
static inline void softirq_clr_runner(unsigned int sirq) { }
#endif
/*
@ -508,6 +537,7 @@ static void do_current_softirqs(int need_rcu_bh_qs)
*/
lock_softirq(i);
local_irq_disable();
softirq_set_runner(i);
/*
* Check with the local_softirq_pending() bits,
* whether we need to process this still or if someone
@ -518,6 +548,7 @@ static void do_current_softirqs(int need_rcu_bh_qs)
set_softirq_pending(pending & ~mask);
do_single_softirq(i, need_rcu_bh_qs);
}
softirq_clr_runner(i);
unlock_softirq(i);
WARN_ON(current->softirq_nestcnt != 1);
}
@ -613,7 +644,7 @@ void thread_do_softirq(void)
}
}
void __raise_softirq_irqoff(unsigned int nr)
static void do_raise_softirq_irqoff(unsigned int nr)
{
trace_softirq_raise(nr);
or_softirq_pending(1UL << nr);
@ -630,12 +661,19 @@ void __raise_softirq_irqoff(unsigned int nr)
__this_cpu_read(ksoftirqd)->softirqs_raised |= (1U << nr);
}
void __raise_softirq_irqoff(unsigned int nr)
{
do_raise_softirq_irqoff(nr);
if (!in_irq() && !current->softirq_nestcnt)
wakeup_softirqd();
}
/*
* This function must run with irqs disabled!
*/
void raise_softirq_irqoff(unsigned int nr)
{
__raise_softirq_irqoff(nr);
do_raise_softirq_irqoff(nr);
/*
* If we're in an hard interrupt we let irq return code deal
@ -657,11 +695,6 @@ void raise_softirq_irqoff(unsigned int nr)
wakeup_softirqd();
}
void do_raise_softirq_irqoff(unsigned int nr)
{
raise_softirq_irqoff(nr);
}
static inline int ksoftirqd_softirq_pending(void)
{
return current->softirqs_raised;