Aren/NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Simplify the last even more; We downgraded to a shared (read) lock, so

Browse Source 
setting recursive has no effect!  The kernel lock manager doesn't allow
an exclusive recursion into a shared lock.  This situation must simply
be avoided.  The only place where this might be a problem is the (ab)use
of uvm_map_pageable() in the Utah-derived pmaps for m68k (they should
either toss the iffy scheme they use completely, or use something like
uvm_fault_wire()).

In addition, once we have looped over uvm_fault_wire(), only upgrade to
an exclusive (write) lock if we need to modify the map again (i.e.
wiring a page failed).
This commit is contained in:
thorpej 1999-06-02 22:40:51 +00:00
parent 23b3336739
commit 779ecdd773
1 changed files with 8 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
sys/uvm/uvm_map.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: uvm_map.c,v 1.51 1999/06/02 21:23:08 thorpej Exp $ */
/* $NetBSD: uvm_map.c,v 1.52 1999/06/02 22:40:51 thorpej Exp $ */
/*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
@ -191,39 +191,6 @@ static void uvm_map_entry_unwire __P((vm_map_t, vm_map_entry_t));
* local inlines
*/
/* XXX Should not exist! */
static __inline void vm_map_set_recursive __P((vm_map_t));
static __inline void
vm_map_set_recursive(map)
vm_map_t map;
{
#ifdef DIAGNOSTIC
if (map->flags & VM_MAP_INTRSAFE)
panic("vm_map_set_recursive: intrsafe map");
#endif
simple_lock(&map->lock.lk_interlock);
map->lock.lk_flags |= LK_CANRECURSE;
simple_unlock(&map->lock.lk_interlock);
}
/* XXX Should not exist! */
static __inline void vm_map_clear_recursive __P((vm_map_t));
static __inline void
vm_map_clear_recursive(map)
vm_map_t map;
{
#ifdef DIAGNOSTIC
if (map->flags & VM_MAP_INTRSAFE)
panic("vm_map_clear_recursive: intrsafe map");
#endif
simple_lock(&map->lock.lk_interlock);
if (map->lock.lk_exclusivecount <= 1)
map->lock.lk_flags &= ~LK_CANRECURSE;
simple_unlock(&map->lock.lk_interlock);
}
/* XXX Should not exist! */
#define vm_map_downgrade(map) \
(void) lockmgr(&(map)->lock, LK_DOWNGRADE, NULL)
@ -2185,18 +2152,6 @@ uvm_map_pageable(map, start, end, new_pageable)
* Pass 2.
*/
/*
* XXX Note, even if we're a kernel map, just set recursion on
* XXX the lock. If the pmap (via uvm_fault()) needs to lock
* XXX this map again in this thread, it will be able to due
* XXX to the recursion setting. Note that we have already
* XXX done what we need to do to the map entries, so we
* XXX should be okay.
*
* JEEZ, THIS IS A MESS!
*/
vm_map_set_recursive(map);
vm_map_downgrade(map);
rv = 0;
@ -2217,13 +2172,12 @@ uvm_map_pageable(map, start, end, new_pageable)
entry = entry->next;
}
/*
* Get back to an exclusive, non-recursive lock. (XXX: see above)
*/
vm_map_upgrade(map);
vm_map_clear_recursive(map);
if (rv) { /* failed? */
/*
* Get back to an exclusive (write) lock.
*/
vm_map_upgrade(map);
/*
* first drop the wiring count on all the entries
* which haven't actually been wired yet.
@ -2242,7 +2196,8 @@ uvm_map_pageable(map, start, end, new_pageable)
return(rv);
}
vm_map_unlock(map);
/* We are holding a read lock here. */
vm_map_unlock_read(map);
UVMHIST_LOG(maphist,"<- done (OK WIRE)",0,0,0,0);
return(KERN_SUCCESS);