kern/38141: lookup/vfs_busy acquire rwlock recursively

[yamt%mwd.biglobe.ne.jp@localhost]

>Number:         38141
>Category:       kern
>Synopsis:       lookup/vfs_busy acquire rwlock recursively
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Mar 03 00:20:00 +0000 2008
>Originator:     YAMAMOTO Takashi <yamt%mwd.biglobe.ne.jp@localhost>
>Release:        NetBSD 4.99.55
>Organization:
        
>Environment:
>Description:
        lookup can acquire rwlock with RW_READER recursively.

        eg.
                lookup (holding the lock via vfs_busy) -> VFS_ROOT
                -> tmpfs_root -> tmpfs_alloc_vp -> getnewvnode
                -> vfs_busy -> rw_enter
>How-To-Repeat:
        code inspection.
>Fix:
        

>Unformatted: