namei lookup vnode locking

[Bruce Evans]

On Thu, 27 Dec 2007, Raja Sivaramakrishnan wrote:

> Thanks for the response - I'll take a look at the handbook.
> Regarding ttywait, it was not called through the ttydrain ioctl.
> ttywait was called through fdfree from exit1() when the login
> process was exiting. I believe this is called with the vnode
> lock held.

Calling device close with the vnode lock held was a large bug.  It was
one of the bugs fixed in 6.2 (devfs_vnops.c 1.114.2.12 2006/10/30 by
kib MFC 1.136 by kib).  It was broken at a higher level by locking the
vnode in vn_close() starting before 6.0 (vfs_vnops.c 1.224 2005/03/13).

Bruce