From owner-svn-src-all@FreeBSD.ORG Thu May 24 04:09:48 2012 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 71427106564A; Thu, 24 May 2012 04:09:48 +0000 (UTC) (envelope-from alc@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c]) by mx1.freebsd.org (Postfix) with ESMTP id 427DA8FC08; Thu, 24 May 2012 04:09:48 +0000 (UTC) Received: from svn.freebsd.org (localhost [127.0.0.1]) by svn.freebsd.org (8.14.4/8.14.4) with ESMTP id q4O49maq014341; Thu, 24 May 2012 04:09:48 GMT (envelope-from alc@svn.freebsd.org) Received: (from alc@localhost) by svn.freebsd.org (8.14.4/8.14.4/Submit) id q4O49mDA014338; Thu, 24 May 2012 04:09:48 GMT (envelope-from alc@svn.freebsd.org) Message-Id: <201205240409.q4O49mDA014338@svn.freebsd.org> From: Alan Cox Date: Thu, 24 May 2012 04:09:48 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org X-SVN-Group: stable-9 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Subject: svn commit: r235878 - stable/9/sys/vm X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 24 May 2012 04:09:48 -0000 Author: alc Date: Thu May 24 04:09:47 2012 New Revision: 235878 URL: http://svn.freebsd.org/changeset/base/235878 Log: MFC r232160 Simplify vmspace_fork()'s control flow by copying immutable data before the vm map locks are acquired. Also, eliminate redundant initialization of the new vm map's timestamp. Modified: stable/9/sys/vm/vm_map.c Directory Properties: stable/9/sys/ (props changed) Modified: stable/9/sys/vm/vm_map.c ============================================================================== --- stable/9/sys/vm/vm_map.c Thu May 24 03:45:13 2012 (r235877) +++ stable/9/sys/vm/vm_map.c Thu May 24 04:09:47 2012 (r235878) @@ -3087,27 +3087,25 @@ struct vmspace * vmspace_fork(struct vmspace *vm1, vm_ooffset_t *fork_charge) { struct vmspace *vm2; - vm_map_t old_map = &vm1->vm_map; - vm_map_t new_map; - vm_map_entry_t old_entry; - vm_map_entry_t new_entry; + vm_map_t new_map, old_map; + vm_map_entry_t new_entry, old_entry; vm_object_t object; int locked; - vm_map_lock(old_map); - if (old_map->busy) - vm_map_wait_busy(old_map); - new_map = NULL; /* silence gcc */ + old_map = &vm1->vm_map; + /* Copy immutable fields of vm1 to vm2. */ vm2 = vmspace_alloc(old_map->min_offset, old_map->max_offset); if (vm2 == NULL) - goto unlock_and_return; + return (NULL); vm2->vm_taddr = vm1->vm_taddr; vm2->vm_daddr = vm1->vm_daddr; vm2->vm_maxsaddr = vm1->vm_maxsaddr; - new_map = &vm2->vm_map; /* XXX */ + vm_map_lock(old_map); + if (old_map->busy) + vm_map_wait_busy(old_map); + new_map = &vm2->vm_map; locked = vm_map_trylock(new_map); /* trylock to silence WITNESS */ KASSERT(locked, ("vmspace_fork: lock failed")); - new_map->timestamp = 1; old_entry = old_map->header.next; @@ -3228,15 +3226,13 @@ vmspace_fork(struct vmspace *vm1, vm_oof } old_entry = old_entry->next; } -unlock_and_return: /* * Use inlined vm_map_unlock() to postpone handling the deferred * map entries, which cannot be done until both old_map and * new_map locks are released. */ sx_xunlock(&old_map->lock); - if (vm2 != NULL) - sx_xunlock(&new_map->lock); + sx_xunlock(&new_map->lock); vm_map_process_deferred(); return (vm2);