[src/trunk]: src/sys/kern ras_fork: don't do PR_WAITOK holding a spinlock.

[yamt <yamt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/834b787a7bf8
branches:  trunk
changeset: 565192:834b787a7bf8
user:      yamt <yamt%NetBSD.org@localhost>
date:      Thu Apr 01 02:37:42 2004 +0000

description:
ras_fork: don't do PR_WAITOK holding a spinlock.

diffstat:

 sys/kern/kern_ras.c |  53 +++++++++++++++++++++++++++++++++++++++++++++++------
 1 files changed, 47 insertions(+), 6 deletions(-)

diffs (83 lines):

diff -r 92326d82dd2c -r 834b787a7bf8 sys/kern/kern_ras.c
--- a/sys/kern/kern_ras.c       Thu Apr 01 02:37:24 2004 +0000
+++ b/sys/kern/kern_ras.c       Thu Apr 01 02:37:42 2004 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_ras.c,v 1.8 2004/04/01 01:49:04 yamt Exp $        */
+/*     $NetBSD: kern_ras.c,v 1.9 2004/04/01 02:37:42 yamt Exp $        */
 
 /*-
  * Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_ras.c,v 1.8 2004/04/01 01:49:04 yamt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_ras.c,v 1.9 2004/04/01 02:37:42 yamt Exp $");
 
 #include <sys/param.h>
 #include <sys/lock.h>
@@ -108,19 +108,60 @@
 ras_fork(struct proc *p1, struct proc *p2)
 {
        struct ras *rp, *nrp;
-       int nras = 0;
+       int nras;
+
+again:
+       /*
+        * first, try to shortcut.
+        */
 
+       if (LIST_EMPTY(&p1->p_raslist))
+               return (0);
+
+       /*
+        * count entries.
+        */
+
+       nras = 0;
        simple_lock(&p1->p_lock);
-       LIST_FOREACH(rp, &p1->p_raslist, ras_list) {
+       LIST_FOREACH(rp, &p1->p_raslist, ras_list)
                nras++;
+       simple_unlock(&p1->p_lock);
+
+       /*
+        * allocate entries.
+        */
+
+       for ( ; nras > 0; nras--) {
                nrp = pool_get(&ras_pool, PR_WAITOK);
-               nrp->ras_startaddr = rp->ras_startaddr;
-               nrp->ras_endaddr = rp->ras_endaddr;
                nrp->ras_hits = 0;
                LIST_INSERT_HEAD(&p2->p_raslist, nrp, ras_list);
        }
+
+       /*
+        * copy entries.
+        */
+
+       simple_lock(&p1->p_lock);
+       nrp = LIST_FIRST(&p2->p_raslist);
+       LIST_FOREACH(rp, &p1->p_raslist, ras_list) {
+               if (nrp == NULL)
+                       break;
+               nrp->ras_startaddr = rp->ras_startaddr;
+               nrp->ras_endaddr = rp->ras_endaddr;
+               nrp = LIST_NEXT(nrp, ras_list);
+       }
        simple_unlock(&p1->p_lock);
 
+       /*
+        * if we lose a race, retry.
+        */
+
+       if (rp != NULL || nrp != NULL) {
+               ras_purgeall(p2);
+               goto again;
+       }
+
        DPRINTF(("ras_fork: p1=%p, p2=%p, nras=%d\n", p1, p2, nras));
 
        return (0);