msleep(9) must prevent kernel from attempting a context switch

during autoconf and after panics.

Tweak and OK guenther, OK miod

diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index d5efc75..e438f0d 100644 (file)
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_synch.c,v 1.119 2015/03/14 03:38:50 jsg Exp $    */
+/*     $OpenBSD: kern_synch.c,v 1.120 2015/05/07 18:30:27 mikeb Exp $  */
 /*     $NetBSD: kern_synch.c,v 1.37 1996/04/22 01:38:37 christos Exp $ */
 
 /*
@@ -141,7 +141,7 @@ tsleep(const volatile void *ident, int priority, const char *wmesg, int timo)
 }
 
 /*
- * Same as tsleep, but if we have a mutex provided, then once we've 
+ * Same as tsleep, but if we have a mutex provided, then once we've
  * entered the sleep queue we drop the mutex. After sleeping we re-lock.
  */
 int
@@ -154,12 +154,30 @@ msleep(const volatile void *ident, struct mutex *mtx, int priority,
        KASSERT((priority & ~(PRIMASK | PCATCH | PNORELOCK)) == 0);
        KASSERT(mtx != NULL);
 
+       if (cold || panicstr) {
+               /*
+                * After a panic, or during autoconfiguration,
+                * just give interrupts a chance, then just return;
+                * don't run any other procs or panic below,
+                * in case this is the idle process and already asleep.
+                */
+               spl = MUTEX_OLDIPL(mtx);
+               MUTEX_OLDIPL(mtx) = safepri;
+               mtx_leave(mtx);
+               if ((priority & PNORELOCK) == 0) {
+                       mtx_enter(mtx);
+                       MUTEX_OLDIPL(mtx) = spl;
+               } else
+                       splx(spl);
+               return (0);
+       }
+
        sleep_setup(&sls, ident, priority, wmesg);
        sleep_setup_timeout(&sls, timo);
        sleep_setup_signal(&sls, priority);
 
        /* XXX - We need to make sure that the mutex doesn't
-        * unblock splsched. This can be made a bit more 
+        * unblock splsched. This can be made a bit more
         * correct when the sched_lock is a mutex.
         */
        spl = MUTEX_OLDIPL(mtx);