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Split sleepq_wakeup_thread() into two functions. sleepq_remove_thread()

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removes a specific thread from a sleep queue.  sleepq_resume_thread()
resumes scheduling of a thread that has been previously removed from a
sleep queue.
- sleepq_catch_signals() just removes a thread from the queue it was just
  added to when a pending signal is found.
- sleepq_signal() and sleepq_broadcast() remove threads from a queue,
  drop the queue lock, and then resume all the previously removed threads.
  This doesn't completely fix the sched_lock <-> sleepq chain LOR, but it
  makes it a little better as we no longer call setrunnble() with a sleep
  queue lock held meaning if setrunnable() tries to wakeup the swapper we
  don't try to lock two sleep queue chains at the same time.
This commit is contained in:
John Baldwin 2004-05-13 20:00:43 +00:00
parent 8d975d4f7c
commit 3335671ddd
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=129188
1 changed files with 50 additions and 13 deletions
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63
sys/kern/subr_sleepqueue.c
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@ -131,8 +131,8 @@ MALLOC_DEFINE(M_SLEEPQUEUE, "sleep queues", "sleep queues");
static int sleepq_check_timeout(void);
static void sleepq_switch(void *wchan);
static void sleepq_timeout(void *arg);
static void sleepq_wakeup_thread(struct sleepqueue *sq, struct thread *td,
int pri);
static void sleepq_remove_thread(struct sleepqueue *sq, struct thread *td);
static void sleepq_resume_thread(struct thread *td, int pri);
/*
* Early initialization of sleep queues that is called from the sleepinit()
@ -332,7 +332,7 @@ sleepq_catch_signals(void *wchan)
mtx_lock_spin(&sched_lock);
if (TD_ON_SLEEPQ(td) && (sig != 0 || do_upcall != 0)) {
mtx_unlock_spin(&sched_lock);
sleepq_wakeup_thread(sq, td, -1);
sleepq_remove_thread(sq, td);
} else
mtx_unlock_spin(&sched_lock);
return (sig);
@ -533,10 +533,10 @@ sleepq_timedwait_sig(void *wchan, int signal_caught)
}
/*
* Removes a thread from a sleep queue and resumes it.
* Removes a thread from a sleep queue.
*/
static void
sleepq_wakeup_thread(struct sleepqueue *sq, struct thread *td, int pri)
sleepq_remove_thread(struct sleepqueue *sq, struct thread *td)
{
struct sleepqueue_chain *sc;
@ -563,14 +563,29 @@ sleepq_wakeup_thread(struct sleepqueue *sq, struct thread *td, int pri)
td->td_sleepqueue = LIST_FIRST(&sq->sq_free);
LIST_REMOVE(td->td_sleepqueue, sq_hash);
mtx_lock_spin(&sched_lock);
td->td_wmesg = NULL;
td->td_wchan = NULL;
mtx_unlock_spin(&sched_lock);
}
/*
* Resumes a thread that was asleep on a queue.
*/
static void
sleepq_resume_thread(struct thread *td, int pri)
{
/*
* Finish resuming the thread.
* Note that thread td might not be sleeping if it is running
* sleepq_catch_signals() on another CPU or is blocked on
* its proc lock to check signals. It doesn't hurt to clear
* the sleeping flag if it isn't set though, so we just always
* do it. However, we can't assert that it is set.
*/
mtx_lock_spin(&sched_lock);
CTR3(KTR_PROC, "sleepq_wakeup: thread %p (pid %d, %s)", td,
td->td_proc->p_pid, td->td_proc->p_comm);
td->td_wmesg = NULL;
td->td_wchan = NULL;
TD_CLR_SLEEPING(td);
/* Adjust priority if requested. */
@ -588,6 +603,7 @@ void
sleepq_signal(void *wchan, int flags, int pri)
{
struct sleepqueue *sq;
struct thread *td;
CTR2(KTR_PROC, "sleepq_signal(%p, %d)", wchan, flags);
KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
@ -601,8 +617,12 @@ sleepq_signal(void *wchan, int flags, int pri)
/* XXX: Do for all sleep queues eventually. */
if (flags & SLEEPQ_CONDVAR)
mtx_assert(sq->sq_lock, MA_OWNED);
sleepq_wakeup_thread(sq, TAILQ_FIRST(&sq->sq_blocked), pri);
/* Remove first thread from queue and awaken it. */
td = TAILQ_FIRST(&sq->sq_blocked);
sleepq_remove_thread(sq, td);
sleepq_release(wchan);
sleepq_resume_thread(td, pri);
}
/*
@ -611,7 +631,9 @@ sleepq_signal(void *wchan, int flags, int pri)
void
sleepq_broadcast(void *wchan, int flags, int pri)
{
TAILQ_HEAD(, thread) list;
struct sleepqueue *sq;
struct thread *td;
CTR2(KTR_PROC, "sleepq_broadcast(%p, %d)", wchan, flags);
KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
@ -625,9 +647,22 @@ sleepq_broadcast(void *wchan, int flags, int pri)
/* XXX: Do for all sleep queues eventually. */
if (flags & SLEEPQ_CONDVAR)
mtx_assert(sq->sq_lock, MA_OWNED);
while (!TAILQ_EMPTY(&sq->sq_blocked))
sleepq_wakeup_thread(sq, TAILQ_FIRST(&sq->sq_blocked), pri);
/* Move blocked threads from the sleep queue to a temporary list. */
TAILQ_INIT(&list);
while (!TAILQ_EMPTY(&sq->sq_blocked)) {
td = TAILQ_FIRST(&sq->sq_blocked);
sleepq_remove_thread(sq, td);
TAILQ_INSERT_TAIL(&list, td, td_slpq);
}
sleepq_release(wchan);
/* Resume all the threads on the temporary list. */
while (!TAILQ_EMPTY(&list)) {
td = TAILQ_FIRST(&list);
TAILQ_REMOVE(&list, td, td_slpq);
sleepq_resume_thread(td, pri);
}
}
/*
@ -675,8 +710,9 @@ sleepq_timeout(void *arg)
MPASS(sq != NULL);
td->td_flags |= TDF_TIMEOUT;
mtx_unlock_spin(&sched_lock);
sleepq_wakeup_thread(sq, td, -1);
sleepq_remove_thread(sq, td);
sleepq_release(wchan);
sleepq_resume_thread(td, -1);
return;
} else if (wchan != NULL)
sleepq_release(wchan);
@ -726,8 +762,9 @@ sleepq_remove(struct thread *td, void *wchan)
MPASS(sq != NULL);
/* Thread is asleep on sleep queue sq, so wake it up. */
sleepq_wakeup_thread(sq, td, -1);
sleepq_remove_thread(sq, td);
sleepq_release(wchan);
sleepq_resume_thread(td, -1);
}
/*