From 1534cd19b5c76e2bbbf1e32e5ab0110eeb62ddd2 Mon Sep 17 00:00:00 2001 From: "Bjoern A. Zeeb" Date: Thu, 5 Jul 2018 17:06:54 +0000 Subject: [PATCH] Split up deadlkres() to make it more readable in anticipation of further changes adding another level of indentation. Some of the logic got simplified with the break out functions. There should be no functional changes. Reviewed by: kib Sponsored by: iXsystems, Inc. Differential Revision: https://reviews.freebsd.org/D15914 --- sys/kern/kern_clock.c | 152 ++++++++++++++++++++---------------------- 1 file changed, 73 insertions(+), 79 deletions(-) diff --git a/sys/kern/kern_clock.c b/sys/kern/kern_clock.c index 1d3441529eb0..6b3a19e0a62c 100644 --- a/sys/kern/kern_clock.c +++ b/sys/kern/kern_clock.c @@ -184,13 +184,71 @@ static int slptime_threshold = 1800; static int blktime_threshold = 900; static int sleepfreq = 3; +static void +deadlres_td_on_lock(struct proc *p, struct thread *td, int blkticks) +{ + int tticks; + + sx_assert(&allproc_lock, SX_LOCKED); + PROC_LOCK_ASSERT(p, MA_OWNED); + THREAD_LOCK_ASSERT(td, MA_OWNED); + /* + * The thread should be blocked on a turnstile, simply check + * if the turnstile channel is in good state. + */ + MPASS(td->td_blocked != NULL); + + tticks = ticks - td->td_blktick; + if (tticks > blkticks) + /* + * Accordingly with provided thresholds, this thread is stuck + * for too long on a turnstile. + */ + panic("%s: possible deadlock detected for %p, " + "blocked for %d ticks\n", __func__, td, tticks); +} + +static void +deadlres_td_sleep_q(struct proc *p, struct thread *td, int slpticks) +{ + void *wchan; + int i, slptype, tticks; + + sx_assert(&allproc_lock, SX_LOCKED); + PROC_LOCK_ASSERT(p, MA_OWNED); + THREAD_LOCK_ASSERT(td, MA_OWNED); + /* + * Check if the thread is sleeping on a lock, otherwise skip the check. + * Drop the thread lock in order to avoid a LOR with the sleepqueue + * spinlock. + */ + wchan = td->td_wchan; + tticks = ticks - td->td_slptick; + slptype = sleepq_type(wchan); + if ((slptype == SLEEPQ_SX || slptype == SLEEPQ_LK) && + tticks > slpticks) { + + /* + * Accordingly with provided thresholds, this thread is stuck + * for too long on a sleepqueue. + * However, being on a sleepqueue, we might still check for the + * blessed list. + */ + for (i = 0; blessed[i] != NULL; i++) + if (!strcmp(blessed[i], td->td_wmesg)) + return; + + panic("%s: possible deadlock detected for %p, " + "blocked for %d ticks\n", __func__, td, tticks); + } +} + static void deadlkres(void) { struct proc *p; struct thread *td; - void *wchan; - int blkticks, i, slpticks, slptype, tryl, tticks; + int blkticks, slpticks, tryl; tryl = 0; for (;;) { @@ -198,14 +256,15 @@ deadlkres(void) slpticks = slptime_threshold * hz; /* - * Avoid to sleep on the sx_lock in order to avoid a possible - * priority inversion problem leading to starvation. + * Avoid to sleep on the sx_lock in order to avoid a + * possible priority inversion problem leading to + * starvation. * If the lock can't be held after 100 tries, panic. */ if (!sx_try_slock(&allproc_lock)) { if (tryl > 100) - panic("%s: possible deadlock detected on allproc_lock\n", - __func__); + panic("%s: possible deadlock detected " + "on allproc_lock\n", __func__); tryl++; pause("allproc", sleepfreq * hz); continue; @@ -218,80 +277,15 @@ deadlkres(void) continue; } FOREACH_THREAD_IN_PROC(p, td) { - thread_lock(td); - if (TD_ON_LOCK(td)) { - - /* - * The thread should be blocked on a - * turnstile, simply check if the - * turnstile channel is in good state. - */ - MPASS(td->td_blocked != NULL); - - tticks = ticks - td->td_blktick; - thread_unlock(td); - if (tticks > blkticks) { - - /* - * Accordingly with provided - * thresholds, this thread is - * stuck for too long on a - * turnstile. - */ - PROC_UNLOCK(p); - sx_sunlock(&allproc_lock); - panic("%s: possible deadlock detected for %p, blocked for %d ticks\n", - __func__, td, tticks); - } - } else if (TD_IS_SLEEPING(td) && - TD_ON_SLEEPQ(td)) { - - /* - * Check if the thread is sleeping on a - * lock, otherwise skip the check. - * Drop the thread lock in order to - * avoid a LOR with the sleepqueue - * spinlock. - */ - wchan = td->td_wchan; - tticks = ticks - td->td_slptick; - thread_unlock(td); - slptype = sleepq_type(wchan); - if ((slptype == SLEEPQ_SX || - slptype == SLEEPQ_LK) && - tticks > slpticks) { - - /* - * Accordingly with provided - * thresholds, this thread is - * stuck for too long on a - * sleepqueue. - * However, being on a - * sleepqueue, we might still - * check for the blessed - * list. - */ - tryl = 0; - for (i = 0; blessed[i] != NULL; - i++) { - if (!strcmp(blessed[i], - td->td_wmesg)) { - tryl = 1; - break; - } - } - if (tryl != 0) { - tryl = 0; - continue; - } - PROC_UNLOCK(p); - sx_sunlock(&allproc_lock); - panic("%s: possible deadlock detected for %p, blocked for %d ticks\n", - __func__, td, tticks); - } - } else - thread_unlock(td); + if (TD_ON_LOCK(td)) + deadlres_td_on_lock(p, td, + blkticks); + else if (TD_IS_SLEEPING(td) && + TD_ON_SLEEPQ(td)) + deadlres_td_sleep_q(p, td, + slpticks); + thread_unlock(td); } PROC_UNLOCK(p); }