Remove unused vm_map_upgrade() & vm_map_downgrade().

Upgrade/downgrade operations on a `vmmaplk' are no longer necessary since
vm_map_busy() completely unlocks it (r1.318 of uvm/uvm_map.c).

ok kettenis@

diff --git a/sys/uvm/uvm_map.c b/sys/uvm/uvm_map.c
index 3951513..7346723 100644 (file)
--- a/sys/uvm/uvm_map.c
+++ b/sys/uvm/uvm_map.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: uvm_map.c,v 1.318 2023/05/20 12:48:36 mpi Exp $       */
+/*     $OpenBSD: uvm_map.c,v 1.319 2023/08/02 09:19:47 mpi Exp $       */
 /*     $NetBSD: uvm_map.c,v 1.86 2000/11/27 08:40:03 chs Exp $ */
 
 /*
@@ -5398,33 +5398,6 @@ vm_map_unlock_read_ln(struct vm_map *map, char *file, int line)
                mtx_leave(&map->mtx);
 }
 
-void
-vm_map_downgrade_ln(struct vm_map *map, char *file, int line)
-{
-       uvm_tree_sanity(map, file, 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);
-}
-
-void
-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);
-       }
-       LPRINTF(("map   lock: %p (at %s %d)\n", map, file, line));
-       uvm_tree_sanity(map, file, line);
-}
-
 void
 vm_map_busy_ln(struct vm_map *map, char *file, int line)
 {

diff --git a/sys/uvm/uvm_map.h b/sys/uvm/uvm_map.h
index 935333a..6f7d540 100644 (file)
--- a/sys/uvm/uvm_map.h
+++ b/sys/uvm/uvm_map.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: uvm_map.h,v 1.86 2023/05/20 12:48:36 mpi Exp $        */
+/*     $OpenBSD: uvm_map.h,v 1.87 2023/08/02 09:19:47 mpi Exp $        */
 /*     $NetBSD: uvm_map.h,v 1.24 2001/02/18 21:19:08 chs Exp $ */
 
 /*
@@ -189,20 +189,15 @@ RBT_PROTOTYPE(uvm_map_addr, vm_map_entry, daddrs.addr_entry,
  *
  *     VM map locking is a little complicated.  There are both shared
  *     and exclusive locks on maps.  However, it is sometimes required
- *     to downgrade an exclusive lock to a shared lock, and upgrade to
- *     an exclusive lock again (to perform error recovery).  However,
- *     another thread *must not* queue itself to receive an exclusive
- *     lock while before we upgrade back to exclusive, otherwise the
- *     error recovery becomes extremely difficult, if not impossible.
+ *     to unlock a VM map (to prevent lock ordering issues) without
+ *     allowing any other thread to modify it.
  *
  *     In order to prevent this scenario, we introduce the notion of
- *     a `busy' map.  A `busy' map is read-locked, but other threads
+ *     a `busy' map.  A `busy' map is unlocked, but other threads
  *     attempting to write-lock wait for this flag to clear before
  *     entering the lock manager.  A map may only be marked busy
- *     when the map is write-locked (and then the map must be downgraded
- *     to read-locked), and may only be marked unbusy by the thread
- *     which marked it busy (holding *either* a read-lock or a
- *     write-lock, the latter being gained by an upgrade).
+ *     when the map is write-locked and may only be marked unbusy by
+ *     the thread which marked it busy.
  *
  *     Access to the map `flags' member is controlled by the `flags_lock'
  *     simple lock.  Note that some flags are static (set once at map
@@ -414,10 +409,6 @@ int                uvm_map_fill_vmmap(struct vm_map *, struct kinfo_vmentry *,
  *
  *     vm_map_unlock_read: release a shared lock on a map.
  *
- *     vm_map_downgrade: downgrade an exclusive lock to a shared lock.
- *
- *     vm_map_upgrade: upgrade a shared lock to an exclusive lock.
- *
  *     vm_map_busy: mark a map as busy.
  *
  *     vm_map_unbusy: clear busy status on a map.
@@ -429,8 +420,6 @@ void                vm_map_lock_ln(struct vm_map*, char*, int);
 void           vm_map_lock_read_ln(struct vm_map*, char*, int);
 void           vm_map_unlock_ln(struct vm_map*, char*, int);
 void           vm_map_unlock_read_ln(struct vm_map*, char*, int);
-void           vm_map_downgrade_ln(struct vm_map*, char*, int);
-void           vm_map_upgrade_ln(struct vm_map*, char*, int);
 void           vm_map_busy_ln(struct vm_map*, char*, int);
 void           vm_map_unbusy_ln(struct vm_map*, char*, int);
 void           vm_map_assert_anylock_ln(struct vm_map*, char*, int);
@@ -442,8 +431,6 @@ void                vm_map_assert_wrlock_ln(struct vm_map*, char*, int);
 #define vm_map_lock_read(map)  vm_map_lock_read_ln(map, __FILE__, __LINE__)
 #define vm_map_unlock(map)     vm_map_unlock_ln(map, __FILE__, __LINE__)
 #define vm_map_unlock_read(map)        vm_map_unlock_read_ln(map, __FILE__, __LINE__)
-#define vm_map_downgrade(map)  vm_map_downgrade_ln(map, __FILE__, __LINE__)
-#define vm_map_upgrade(map)    vm_map_upgrade_ln(map, __FILE__, __LINE__)
 #define vm_map_busy(map)       vm_map_busy_ln(map, __FILE__, __LINE__)
 #define vm_map_unbusy(map)     vm_map_unbusy_ln(map, __FILE__, __LINE__)
 #define vm_map_assert_anylock(map)     \
@@ -456,8 +443,6 @@ void                vm_map_assert_wrlock_ln(struct vm_map*, char*, int);
 #define vm_map_lock_read(map)  vm_map_lock_read_ln(map, NULL, 0)
 #define vm_map_unlock(map)     vm_map_unlock_ln(map, NULL, 0)
 #define vm_map_unlock_read(map)        vm_map_unlock_read_ln(map, NULL, 0)
-#define vm_map_downgrade(map)  vm_map_downgrade_ln(map, NULL, 0)
-#define vm_map_upgrade(map)    vm_map_upgrade_ln(map, NULL, 0)
 #define vm_map_busy(map)       vm_map_busy_ln(map, NULL, 0)
 #define vm_map_unbusy(map)     vm_map_unbusy_ln(map, NULL, 0)
 #define vm_map_assert_anylock(map)     vm_map_assert_anylock_ln(map, NULL, 0)