Add locking for interrupt-safe maps (those that have the VM_MAP_INTRSAFE flag

set).  Since we cannot sleep in that case, use a mutex instead of an rwlock.
This is ok as the more complex code paths in the uvm code are not entered
for interrupt-safe maps as paging isn't allowed in those maps.

ok tedu@

2 files changed, 17 insertions, 3 deletions

diff --git a/sys/uvm/uvm_map.c b/sys/uvm/uvm_map.c
index 0e846ff5832..9c51fa1478c 100644
--- a/sys/uvm/uvm_map.c
+++ b/sys/uvm/uvm_map.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_map.c,v 1.197 2015/09/09 14:52:12 miod Exp $	*/
+/*	$OpenBSD: uvm_map.c,v 1.198 2015/09/09 23:33:37 kettenis Exp $	*/
 /*	$NetBSD: uvm_map.c,v 1.86 2000/11/27 08:40:03 chs Exp $	*/
 
 /*
@@ -2392,6 +2392,7 @@ uvm_map_setup(struct vm_map *map, vaddr_t min, vaddr_t max, int flags)
 	map->flags = flags;
 	map->timestamp = 0;
 	rw_init(&map->lock, "vmmaplk");
+	mtx_init(&map->mtx, IPL_VM);
 	mtx_init(&map->flags_lock, IPL_VM);
 
 	/* Configure the allocators. */
@@ -4949,7 +4950,7 @@ vm_map_lock_try_ln(struct vm_map *map, char *file, int line)
 	boolean_t rv;
 
 	if (map->flags & VM_MAP_INTRSAFE) {
-		rv = TRUE;
+		rv = mtx_enter_try(&map->mtx);
 	} else {
 		mtx_enter(&map->flags_lock);
 		if (map->flags & VM_MAP_BUSY) {
@@ -5000,6 +5001,8 @@ tryagain:
 			goto tryagain;
 		}
 		mtx_leave(&map->flags_lock);
+	} else {
+		mtx_enter(&map->mtx);
 	}
 
 	map->timestamp++;
@@ -5013,6 +5016,8 @@ vm_map_lock_read_ln(struct vm_map *map, char *file, int line)
 {
 	if ((map->flags & VM_MAP_INTRSAFE) == 0)
 		rw_enter_read(&map->lock);
+	else
+		mtx_enter(&map->mtx);
 	LPRINTF(("map   lock: %p (at %s %d)\n", map, file, line));
 	uvm_tree_sanity(map, file, line);
 	uvm_tree_size_chk(map, file, line);
@@ -5026,6 +5031,8 @@ vm_map_unlock_ln(struct vm_map *map, char *file, int line)
 	LPRINTF(("map unlock: %p (at %s %d)\n", map, file, line));
 	if ((map->flags & VM_MAP_INTRSAFE) == 0)
 		rw_exit(&map->lock);
+	else
+		mtx_leave(&map->mtx);
 }
 
 void
@@ -5036,6 +5043,8 @@ vm_map_unlock_read_ln(struct vm_map *map, char *file, int line)
 	LPRINTF(("map unlock: %p (at %s %d)\n", map, file, line));
 	if ((map->flags & VM_MAP_INTRSAFE) == 0)
 		rw_exit_read(&map->lock);
+	else
+		mtx_leave(&map->mtx);
 }
 
 void
@@ -5045,6 +5054,7 @@ vm_map_downgrade_ln(struct vm_map *map, char *file, int line)
 	uvm_tree_size_chk(map, file, line);
 	LPRINTF(("map unlock: %p (at %s %d)\n", map, file, line));
 	LPRINTF(("map   lock: %p (at %s %d)\n", map, file, line));
+	KASSERT((map->flags & VM_MAP_INTRSAFE) == 0);
 	if ((map->flags & VM_MAP_INTRSAFE) == 0)
 		rw_enter(&map->lock, RW_DOWNGRADE);
 }
@@ -5055,6 +5065,7 @@ vm_map_upgrade_ln(struct vm_map *map, char *file, int line)
 	/* XXX: RO */ uvm_tree_sanity(map, file, line);
 	/* XXX: RO */ uvm_tree_size_chk(map, file, line);
 	LPRINTF(("map unlock: %p (at %s %d)\n", map, file, line));
+	KASSERT((map->flags & VM_MAP_INTRSAFE) == 0);
 	if ((map->flags & VM_MAP_INTRSAFE) == 0) {
 		rw_exit_read(&map->lock);
 		rw_enter_write(&map->lock);
@@ -5066,6 +5077,7 @@ vm_map_upgrade_ln(struct vm_map *map, char *file, int line)
 void
 vm_map_busy_ln(struct vm_map *map, char *file, int line)
 {
+	KASSERT((map->flags & VM_MAP_INTRSAFE) == 0);
 	mtx_enter(&map->flags_lock);
 	map->flags |= VM_MAP_BUSY;
 	mtx_leave(&map->flags_lock);
@@ -5076,6 +5088,7 @@ vm_map_unbusy_ln(struct vm_map *map, char *file, int line)
 {
 	int oflags;
 
+	KASSERT((map->flags & VM_MAP_INTRSAFE) == 0);
 	mtx_enter(&map->flags_lock);
 	oflags = map->flags;
 	map->flags &= ~(VM_MAP_BUSY|VM_MAP_WANTLOCK);
diff --git a/sys/uvm/uvm_map.h b/sys/uvm/uvm_map.h
index c23e070f703..38604b577d6 100644
--- a/sys/uvm/uvm_map.h
+++ b/sys/uvm/uvm_map.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_map.h,v 1.54 2015/03/30 21:08:40 miod Exp $	*/
+/*	$OpenBSD: uvm_map.h,v 1.55 2015/09/09 23:33:37 kettenis Exp $	*/
 /*	$NetBSD: uvm_map.h,v 1.24 2001/02/18 21:19:08 chs Exp $	*/
 
 /*
@@ -288,6 +288,7 @@ RB_PROTOTYPE(uvm_map_addr, vm_map_entry, daddrs.addr_entry,
 struct vm_map {
 	struct pmap *		pmap;		/* Physical map */
 	struct rwlock		lock;		/* Lock for map data */
+	struct mutex		mtx;
 
 	struct uvm_map_addr	addr;		/* Entry tree, by addr */