Date: Sun, 8 Feb 2009 19:55:03 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r188323 - head/sys/vm Message-ID: <200902081955.n18Jt3Po032530@svn.freebsd.org>
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Author: kib Date: Sun Feb 8 19:55:03 2009 New Revision: 188323 URL: http://svn.freebsd.org/changeset/base/188323 Log: Lock the new map in vmspace_fork(). The newly allocated map should not be accessible outside vmspace_fork() yet, but locking it would satisfy the protocol of the vm_map_entry_link() and other functions called from vmspace_fork(). Use trylock that is supposedly cannot fail, to silence WITNESS warning of the nested acquisition of the sx lock with the same name. Suggested and reviewed by: tegge Modified: head/sys/vm/vm_map.c Modified: head/sys/vm/vm_map.c ============================================================================== --- head/sys/vm/vm_map.c Sun Feb 8 19:53:37 2009 (r188322) +++ head/sys/vm/vm_map.c Sun Feb 8 19:55:03 2009 (r188323) @@ -2679,6 +2679,7 @@ vmspace_fork(struct vmspace *vm1) vm_map_entry_t old_entry; vm_map_entry_t new_entry; vm_object_t object; + int locked; vm_map_lock(old_map); @@ -2689,6 +2690,8 @@ vmspace_fork(struct vmspace *vm1) vm2->vm_daddr = vm1->vm_daddr; vm2->vm_maxsaddr = vm1->vm_maxsaddr; new_map = &vm2->vm_map; /* XXX */ + 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; @@ -2780,6 +2783,8 @@ vmspace_fork(struct vmspace *vm1) } unlock_and_return: vm_map_unlock(old_map); + if (vm2 != NULL) + vm_map_unlock(new_map); return (vm2); }
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