CVS commit: [matt-nb5-mips64] src/sys/arch/mips/mips

[Matt Thomas]

Module Name:    src
Committed By:   matt
Date:           Thu Apr  8 16:05:31 UTC 2010

Modified Files:
        src/sys/arch/mips/mips [matt-nb5-mips64]: pmap.c

Log Message:
Fix problem where pmap_clear_modify could go into an infinite loop.
Spotted by cyber.


To generate a diff of this commit:
cvs rdiff -u -r1.179.16.22 -r1.179.16.23 src/sys/arch/mips/mips/pmap.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.


Modified files:

Index: src/sys/arch/mips/mips/pmap.c
diff -u src/sys/arch/mips/mips/pmap.c:1.179.16.22 src/sys/arch/mips/mips/pmap.c:1.179.16.23
--- src/sys/arch/mips/mips/pmap.c:1.179.16.22	Thu Mar 11 08:19:01 2010
+++ src/sys/arch/mips/mips/pmap.c	Thu Apr  8 16:05:31 2010
@@ -1,4 +1,4 @@
-/*	$NetBSD: pmap.c,v 1.179.16.22 2010/03/11 08:19:01 matt Exp $	*/
+/*	$NetBSD: pmap.c,v 1.179.16.23 2010/04/08 16:05:31 matt Exp $	*/
 
 /*-
  * Copyright (c) 1998, 2001 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
 
 #include <sys/cdefs.h>
 
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.179.16.22 2010/03/11 08:19:01 matt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.179.16.23 2010/04/08 16:05:31 matt Exp $");
 
 /*
  *	Manages physical address maps.
@@ -1886,7 +1886,8 @@
 bool
 pmap_clear_modify(struct vm_page *pg)
 {
-	struct pv_entry *pv = &pg->mdpage.pvh_first;
+	pv_entry_t pv = &pg->mdpage.pvh_first;
+	pv_entry_t pv_next;
 	uint16_t gen;
 
 	PMAP_COUNT(clear_modify);
@@ -1916,11 +1917,12 @@
 	 */
 	kpreempt_disable();
 	gen = VM_PAGE_PVLIST_LOCK(pg, false);
-	while (pv != NULL) {
+	for (; pv != NULL; pv = pv_next) {
 		pmap_t pmap = pv->pv_pmap;
 		vaddr_t va = pv->pv_va;
 		pt_entry_t *pte;
 		uint32_t pt_entry;
+		pv_next = pv->pv_next;
 		if (pmap == pmap_kernel()) {
 			pte = kvtopte(va);
 		} else {
@@ -1946,13 +1948,11 @@
 		VM_PAGE_PVLIST_UNLOCK(pg);
 		pmap_tlb_invalidate_addr(pmap, va);
 		pmap_update(pmap);
-		if (gen != VM_PAGE_PVLIST_LOCK(pg, false)) {
+		if (__predict_false(gen != VM_PAGE_PVLIST_LOCK(pg, false))) {
 			/*
 			 * The list changed!  So restart from the beginning.
 			 */
-			pv = &pg->mdpage.pvh_first;
-		} else {
-			pv = pv->pv_next;
+			pv_next = &pg->mdpage.pvh_first;
 		}
 	}
 	VM_PAGE_PVLIST_UNLOCK(pg);