From: mikeb <mikeb@openbsd.org>
Date: Tue, 12 May 2015 09:30:35 +0000 (+0000)
Subject: Drop and reacquire the kernel lock in the vfs_shutdown and "cold"
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=b86c486e388a674c4ec8ae3acff31b5a14186b22;p=openbsd

Drop and reacquire the kernel lock in the vfs_shutdown and "cold"
portions of msleep and tsleep to give interrupts a chance to run
on other CPUs.

Tweak and OK kettenis
---

diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index e438f0dac99..7a49c354ae5 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_synch.c,v 1.120 2015/05/07 18:30:27 mikeb Exp $	*/
+/*	$OpenBSD: kern_synch.c,v 1.121 2015/05/12 09:30:35 mikeb Exp $	*/
 /*	$NetBSD: kern_synch.c,v 1.37 1996/04/22 01:38:37 christos Exp $	*/
 
 /*
@@ -104,6 +104,9 @@ tsleep(const volatile void *ident, int priority, const char *wmesg, int timo)
 {
 	struct sleep_state sls;
 	int error, error1;
+#ifdef MULTIPROCESSOR
+	int hold_count;
+#endif
 
 	KASSERT((priority & ~(PRIMASK | PCATCH)) == 0);
 
@@ -121,6 +124,12 @@ tsleep(const volatile void *ident, int priority, const char *wmesg, int timo)
 		 */
 		s = splhigh();
 		splx(safepri);
+#ifdef MULTIPROCESSOR
+		if (__mp_lock_held(&kernel_lock)) {
+			hold_count = __mp_release_all(&kernel_lock);
+			__mp_acquire_count(&kernel_lock, hold_count);
+		}
+#endif
 		splx(s);
 		return (0);
 	}
@@ -150,6 +159,9 @@ msleep(const volatile void *ident, struct mutex *mtx, int priority,
 {
 	struct sleep_state sls;
 	int error, error1, spl;
+#ifdef MULTIPROCESSOR
+	int hold_count;
+#endif
 
 	KASSERT((priority & ~(PRIMASK | PCATCH | PNORELOCK)) == 0);
 	KASSERT(mtx != NULL);
@@ -164,6 +176,12 @@ msleep(const volatile void *ident, struct mutex *mtx, int priority,
 		spl = MUTEX_OLDIPL(mtx);
 		MUTEX_OLDIPL(mtx) = safepri;
 		mtx_leave(mtx);
+#ifdef MULTIPROCESSOR
+		if (__mp_lock_held(&kernel_lock)) {
+			hold_count = __mp_release_all(&kernel_lock);
+			__mp_acquire_count(&kernel_lock, hold_count);
+		}
+#endif
 		if ((priority & PNORELOCK) == 0) {
 			mtx_enter(mtx);
 			MUTEX_OLDIPL(mtx) = spl;
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 1d02681e8a2..2c1da15cba6 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_subr.c,v 1.230 2015/03/14 03:38:51 jsg Exp $	*/
+/*	$OpenBSD: vfs_subr.c,v 1.231 2015/05/12 09:30:35 mikeb Exp $	*/
 /*	$NetBSD: vfs_subr.c,v 1.53 1996/04/22 01:39:13 christos Exp $	*/
 
 /*
@@ -1614,6 +1614,9 @@ vfs_syncwait(int verbose)
 	struct buf *bp;
 	int iter, nbusy, dcount, s;
 	struct proc *p;
+#ifdef MULTIPROCESSOR
+	int hold_count;
+#endif
 
 	p = curproc? curproc : &proc0;
 	sys_sync(p, (void *)0, (register_t *)0);
@@ -1648,7 +1651,17 @@ vfs_syncwait(int verbose)
 			break;
 		if (verbose)
 			printf("%d ", nbusy);
+#ifdef MULTIPROCESSOR
+		if (__mp_lock_held(&kernel_lock))
+			hold_count = __mp_release_all(&kernel_lock);
+		else
+			hold_count = 0;
+#endif
 		DELAY(40000 * iter);
+#ifdef MULTIPROCESSOR
+		if (hold_count)
+			__mp_acquire_count(&kernel_lock, hold_count);
+#endif
 	}
 
 	return nbusy;