Date: Tue, 2 Feb 2016 16:53:22 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Jov <zhao6014@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Fwd: [BUGS] BUG #13900: stop standby failed with writer process hang(happen 3 times in 2 days) Message-ID: <20160202145322.GA91220@kib.kiev.ua> In-Reply-To: <CADyrUxMN3_=thr0LutMMkpzkVzFr_NtYOQPM2Dn2Ce_JtSKROg@mail.gmail.com> References: <20160130071346.31022.37189@wrigleys.postgresql.org> <CADyrUxM9jWVrUZYkUYP6vxgg_eWOuCqCQTqEERQ6iSq11DjUeA@mail.gmail.com> <20160131162929.GI91220@kib.kiev.ua> <CADyrUxOw%2Bn-ZB9f71v9PFjB_Mk=x8-DMZWqsD0GXK0DYEVw2fA@mail.gmail.com> <20160201190415.GO91220@kib.kiev.ua> <CADyrUxMN3_=thr0LutMMkpzkVzFr_NtYOQPM2Dn2Ce_JtSKROg@mail.gmail.com>
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On Tue, Feb 02, 2016 at 09:36:19AM +0800, Jov wrote:
> ???Thanks for your info,Belousov.
> Would you please point which PR or which commit I can exam???I can not move
> to 10 stable now,maybe I can avoid trigger this bug or add some monitor???.
stable/10 is not fixed as well.
I do not have a good suggestion rather then to sync kern_timeout.c with
head. After that, you need one more patch.
diff --git a/sys/kern/kern_timeout.c b/sys/kern/kern_timeout.c
index 9c9d25f..e827665 100644
--- a/sys/kern/kern_timeout.c
+++ b/sys/kern/kern_timeout.c
@@ -1162,7 +1162,7 @@ _callout_stop_safe(struct callout *c, int safe, void (*drain)(void *))
int direct, sq_locked, use_lock;
int not_on_a_list;
- if (safe)
+ if ((safe & CS_DRAIN) != 0)
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock,
"calling %s", __func__);
@@ -1170,7 +1170,7 @@ _callout_stop_safe(struct callout *c, int safe, void (*drain)(void *))
* Some old subsystems don't hold Giant while running a callout_stop(),
* so just discard this check for the moment.
*/
- if (!safe && c->c_lock != NULL) {
+ if ((safe & CS_DRAIN) == 0 && c->c_lock != NULL) {
if (c->c_lock == &Giant.lock_object)
use_lock = mtx_owned(&Giant);
else {
@@ -1253,7 +1253,7 @@ again:
return (-1);
}
- if (safe) {
+ if ((safe & CS_DRAIN) != 0) {
/*
* The current callout is running (or just
* about to run) and blocking is allowed, so
@@ -1370,7 +1370,7 @@ again:
cc_exec_drain(cc, direct) = drain;
}
CC_UNLOCK(cc);
- return (0);
+ return ((safe & CS_MIGRBLOCK) != 0);
}
CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
c, c->c_func, c->c_arg);
diff --git a/sys/kern/subr_sleepqueue.c b/sys/kern/subr_sleepqueue.c
index bbbec92..12908f6 100644
--- a/sys/kern/subr_sleepqueue.c
+++ b/sys/kern/subr_sleepqueue.c
@@ -586,7 +586,8 @@ sleepq_check_timeout(void)
* another CPU, so synchronize with it to avoid having it
* accidentally wake up a subsequent sleep.
*/
- else if (callout_stop(&td->td_slpcallout) == 0) {
+ else if (_callout_stop_safe(&td->td_slpcallout, CS_MIGRBLOCK, NULL)
+ == 0) {
td->td_flags |= TDF_TIMEOUT;
TD_SET_SLEEPING(td);
mi_switch(SW_INVOL | SWT_SLEEPQTIMO, NULL);
diff --git a/sys/sys/callout.h b/sys/sys/callout.h
index 3e71c87..51dc137 100644
--- a/sys/sys/callout.h
+++ b/sys/sys/callout.h
@@ -62,6 +62,9 @@ struct callout_handle {
struct callout *callout;
};
+#define CS_DRAIN 0x0001
+#define CS_MIGRBLOCK 0x0002
+
#ifdef _KERNEL
/*
* Note the flags field is actually *two* fields. The c_flags
@@ -81,7 +84,7 @@ struct callout_handle {
*/
#define callout_active(c) ((c)->c_flags & CALLOUT_ACTIVE)
#define callout_deactivate(c) ((c)->c_flags &= ~CALLOUT_ACTIVE)
-#define callout_drain(c) _callout_stop_safe(c, 1, NULL)
+#define callout_drain(c) _callout_stop_safe(c, CS_DRAIN, NULL)
void callout_init(struct callout *, int);
void _callout_init_lock(struct callout *, struct lock_object *, int);
#define callout_init_mtx(c, mtx, flags) \
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