[PATCH] Switch nfs/callback.c to using struct pid, not pid_t

[Christoph Hellwig]

On Wed, Aug 29, 2007 at 05:36:24PM +0400, Pavel Emelyanov wrote:
> Pid namespaces make it dangerous to use pid and tgid values
> when run in some namespace. The struct pid itself is going
> to be the only way for working with task pids, so make the
> nfs callback thread use it.
> 
> Since nfs_callback_info.pid is set to current's one and reset
> on the thread exit, it is safe not to get the struct pid. 
> 
> Since this pid is used later under lock_kernel() w/o sleeping 
> operations, checking for i to be not NULL and killing the 
> thread with kill_pid() is safe.

NACK.  This just makes the code even more obscure.  Please get rid
of the pid references entirely and convert the code to the kthread
API.