Date: Sun, 19 Sep 2010 17:43:22 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r212868 - head/sys/vm Message-ID: <201009191743.o8JHhMpT009889@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: alc Date: Sun Sep 19 17:43:22 2010 New Revision: 212868 URL: http://svn.freebsd.org/changeset/base/212868 Log: Make refinements to r212824. In particular, don't make vm_map_unlock_nodefer() part of the synchronization interface for maps. Add comments to vm_map_unlock_and_wait() and vm_map_wakeup() describing how they should be used. In particular, describe the deferred deallocations issue with vm_map_unlock_and_wait(). Redo the implementation of vm_map_unlock_and_wait() so that it passes along the caller's file and line information, just like the other map locking primitives. Reviewed by: kib X-MFC after: r212824 Modified: head/sys/vm/vm_map.c head/sys/vm/vm_map.h Modified: head/sys/vm/vm_map.c ============================================================================== --- head/sys/vm/vm_map.c Sun Sep 19 16:35:42 2010 (r212867) +++ head/sys/vm/vm_map.c Sun Sep 19 17:43:22 2010 (r212868) @@ -470,16 +470,6 @@ vm_map_process_deferred(void) } void -_vm_map_unlock_nodefer(vm_map_t map, const char *file, int line) -{ - - if (map->system_map) - _mtx_unlock_flags(&map->system_mtx, 0, file, line); - else - _sx_xunlock(&map->lock, file, line); -} - -void _vm_map_unlock(vm_map_t map, const char *file, int line) { @@ -637,19 +627,37 @@ _vm_map_assert_locked_read(vm_map_t map, #endif /* - * vm_map_unlock_and_wait: + * _vm_map_unlock_and_wait: + * + * Atomically releases the lock on the specified map and puts the calling + * thread to sleep. The calling thread will remain asleep until either + * vm_map_wakeup() is performed on the map or the specified timeout is + * exceeded. + * + * WARNING! This function does not perform deferred deallocations of + * objects and map entries. Therefore, the calling thread is expected to + * reacquire the map lock after reawakening and later perform an ordinary + * unlock operation, such as vm_map_unlock(), before completing its + * operation on the map. */ int -vm_map_unlock_and_wait(vm_map_t map, int timo) +_vm_map_unlock_and_wait(vm_map_t map, int timo, const char *file, int line) { mtx_lock(&map_sleep_mtx); - vm_map_unlock_nodefer(map); - return (msleep(&map->root, &map_sleep_mtx, PDROP | PVM, "vmmaps", timo)); + if (map->system_map) + _mtx_unlock_flags(&map->system_mtx, 0, file, line); + else + _sx_xunlock(&map->lock, file, line); + return (msleep(&map->root, &map_sleep_mtx, PDROP | PVM, "vmmaps", + timo)); } /* * vm_map_wakeup: + * + * Awaken any threads that have slept on the map using + * vm_map_unlock_and_wait(). */ void vm_map_wakeup(vm_map_t map) @@ -657,8 +665,8 @@ vm_map_wakeup(vm_map_t map) /* * Acquire and release map_sleep_mtx to prevent a wakeup() - * from being performed (and lost) between the vm_map_unlock() - * and the msleep() in vm_map_unlock_and_wait(). + * from being performed (and lost) between the map unlock + * and the msleep() in _vm_map_unlock_and_wait(). */ mtx_lock(&map_sleep_mtx); mtx_unlock(&map_sleep_mtx); Modified: head/sys/vm/vm_map.h ============================================================================== --- head/sys/vm/vm_map.h Sun Sep 19 16:35:42 2010 (r212867) +++ head/sys/vm/vm_map.h Sun Sep 19 17:43:22 2010 (r212868) @@ -266,7 +266,7 @@ vmspace_pmap(struct vmspace *vmspace) void _vm_map_lock(vm_map_t map, const char *file, int line); void _vm_map_unlock(vm_map_t map, const char *file, int line); -void _vm_map_unlock_nodefer(vm_map_t map, const char *file, int line); +int _vm_map_unlock_and_wait(vm_map_t map, int timo, const char *file, int line); void _vm_map_lock_read(vm_map_t map, const char *file, int line); void _vm_map_unlock_read(vm_map_t map, const char *file, int line); int _vm_map_trylock(vm_map_t map, const char *file, int line); @@ -274,13 +274,12 @@ int _vm_map_trylock_read(vm_map_t map, c int _vm_map_lock_upgrade(vm_map_t map, const char *file, int line); void _vm_map_lock_downgrade(vm_map_t map, const char *file, int line); int vm_map_locked(vm_map_t map); -int vm_map_unlock_and_wait(vm_map_t map, int timo); void vm_map_wakeup(vm_map_t map); #define vm_map_lock(map) _vm_map_lock(map, LOCK_FILE, LOCK_LINE) #define vm_map_unlock(map) _vm_map_unlock(map, LOCK_FILE, LOCK_LINE) -#define vm_map_unlock_nodefer(map) \ - _vm_map_unlock_nodefer(map, LOCK_FILE, LOCK_LINE) +#define vm_map_unlock_and_wait(map, timo) \ + _vm_map_unlock_and_wait(map, timo, LOCK_FILE, LOCK_LINE) #define vm_map_lock_read(map) _vm_map_lock_read(map, LOCK_FILE, LOCK_LINE) #define vm_map_unlock_read(map) _vm_map_unlock_read(map, LOCK_FILE, LOCK_LINE) #define vm_map_trylock(map) _vm_map_trylock(map, LOCK_FILE, LOCK_LINE)
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201009191743.o8JHhMpT009889>