Re: [PATCH 5/9] rpc: call release_pipe only on last close

["J. Bruce Fields" <bfields@fieldses.org>]

On Mon, Nov 10, 2008 at 02:11:37PM -0500, Trond Myklebust wrote:
> On Sun, 2008-11-09 at 16:04 -0500, J. Bruce Fields wrote:
> > I can't see any reason we particularly need to call this until the last
> > gssd closes the pipe.
> 
> There's a very good reason: if we call rpc_close_pipes() then it is
> because the kernel listener is shutting down. At that point, we want to
> return EPIPE for all future read() or write() attempts by gssd.

Sure.  This doesn't interfere with that--we're still calling
release_pipe() itself (which is the function that sets rpci->ops to
NULL), it's only the ->release_pipe() op that we're not calling.

> > Also, this allows to guarantee that open_pipe and release_pipe are
> > called strictly in pairs; open_pipe on the first open, release_pipe on
> > the last close.  That'll make it very easy for the gss code to keep
> > track of which pipes gssd is using.
> 
> ...unless the gss code is no longer running.

I'm not following you.

Note the patch calls ->release_pipe() at close_pipe() time if there are
still opens (and then subsequent closes become no-ops).  So it does
guarantee that there's always a matching call.

So my patch description was wrong: "last close" should be something like
"last close, or destruction of an opened pipe."  I'll fix that.

--b.