Re: [PATCH 1/4] svcrpc: never clear XPT_BUSY on dead xprt

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

On Mon, Oct 25, 2010 at 08:28:58PM -0400, J. Bruce Fields wrote:
> On Mon, Oct 25, 2010 at 08:11:45PM -0400, J. Bruce Fields wrote:
> > On Tue, Oct 26, 2010 at 10:54:47AM +1100, Neil Brown wrote:
> > > Note that once we always set XPT_BUSY and it stays set.  So we call
> > > svc_delete_xprt instread of svc_close_xprt.
> > > 
> > > Maybe we don't actually need to list_del_init - both the pool and the xprt
> > > will soon be freed and if there is linkage between them, who cares??
> > > In that case we wouldn't need to for_each_pool after all ???
> 
> So, untested:

Ditto.  But, hey, it deletes more code, it must be good.

--b.

commit 99401f6f6c3d0782ef79bb37749ace2accd4c79a
Author: J. Bruce Fields <bfields@redhat.com>
Date:   Mon Oct 25 20:24:48 2010 -0400

    svcrpc: simplify svc_close_xprt, fix minor race
    
    We're assuming that in the XPT_BUSY case, somebody else will take care
    of the close.  But that's not necessarily the case (e.g. if
    svc_xprt_enqueue() exits due to a lack of write space).  So the close
    could in theory be delayed indefinitely.  We should be calling
    svc_xprt_enqueue() after every set of XPT_CLOSE.
    
    Also with svc_close_all() no longer relying on svc_close, it no longer
    needs to be able to immediately do the svc_delete_xprt() itself.
    
    Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 8c018df..dfee123 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -928,11 +928,7 @@ void svc_delete_xprt(struct svc_xprt *xprt)
 void svc_close_xprt(struct svc_xprt *xprt)
 {
 	set_bit(XPT_CLOSE, &xprt->xpt_flags);
-	if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags))
-		/* someone else will have to effect the close */
-		return;
-
-	svc_delete_xprt(xprt);
+	svc_xprt_enqueue(xprt);
 }
 EXPORT_SYMBOL_GPL(svc_close_xprt);