Return-Path: Received: from fieldses.org ([174.143.236.118]:56147 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757731Ab0JYXEA (ORCPT ); Mon, 25 Oct 2010 19:04:00 -0400 Date: Mon, 25 Oct 2010 19:03:35 -0400 From: "J. Bruce Fields" To: Neil Brown Cc: "J. Bruce Fields" , linux-nfs@vger.kernel.org, Menyhart Zoltan Subject: Re: [PATCH 1/4] svcrpc: never clear XPT_BUSY on dead xprt Message-ID: <20101025230331.GF13523@fieldses.org> References: <20101025010923.GB11470@fieldses.org> <1287969693-12340-1-git-send-email-bfields@redhat.com> <20101025124357.63b966bb@notabene> <20101025202155.GD13523@fieldses.org> <20101026095836.61bf6a38@notabene> Content-Type: text/plain; charset=us-ascii In-Reply-To: <20101026095836.61bf6a38@notabene> Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Tue, Oct 26, 2010 at 09:58:36AM +1100, Neil Brown wrote: > On Mon, 25 Oct 2010 16:21:56 -0400 > "J. Bruce Fields" wrote: > > > On Mon, Oct 25, 2010 at 12:43:57PM +1100, Neil Brown wrote: > > > On Sun, 24 Oct 2010 21:21:30 -0400 > > > "J. Bruce Fields" wrote: > > > > > > > Once an xprt has been deleted, there's no reason to allow it to be > > > > enqueued--at worst, that might cause the xprt to be re-added to some > > > > global list, resulting in later corruption. > > > > > > > > Signed-off-by: J. Bruce Fields > > > > > > Yep, this makes svc_close_xprt() behave the same way as svc_recv() which > > > calls svc_delete_xprt but does not clear XPT_BUSY. The other branches in > > > svc_recv call svc_xprt_received, but the XPT_CLOSE branch doesn't > > > > > > Reviewed-by: NeilBrown > > > > Also, of course: > > > > > > svc_xprt_get(xprt); > > > > svc_delete_xprt(xprt); > > > > - clear_bit(XPT_BUSY, &xprt->xpt_flags); > > > > svc_xprt_put(xprt); > > > > The get/put is pointless: the only reason I can see for doing that of > > course was to be able to safely clear the bit afterwards. > > > > Agreed. > > I like patches that get rid of code!! Unfortunately, I'm stuck on just one more point: is svc_close_all() really safe? It assumes it doesn't need any locking to speak of any more because the server threads are gone--but the xprt's themselves could still be producing events, right? (So data could be arriving that results in calls to svc_xprt_enqueue, for example?) If that's right, I'm not sure what to do there.... --b.