Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-ie0-f175.google.com ([209.85.223.175]:35814 "EHLO mail-ie0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757010AbaAFX2k convert rfc822-to-8bit (ORCPT ); Mon, 6 Jan 2014 18:28:40 -0500 Received: by mail-ie0-f175.google.com with SMTP id x13so19408646ief.20 for ; Mon, 06 Jan 2014 15:28:40 -0800 (PST) Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.1 \(1827\)) Subject: Re: [PATCH] SUNRPC: fix a memory leak for tcp NFSv4.1 backchannel From: Trond Myklebust In-Reply-To: <20140106225346.GB3342@fieldses.org> Date: Mon, 6 Jan 2014 18:28:38 -0500 Cc: Kinglong Mee , Linux NFS Mailing List Message-Id: References: <52CA7862.1020203@gmail.com> <20140106184926.GC31764@fieldses.org> <24D159B0-C13D-43A6-B307-2B967E154353@primarydata.com> <20140106225346.GB3342@fieldses.org> To: Dr Fields James Bruce Sender: linux-nfs-owner@vger.kernel.org List-ID: On Jan 6, 2014, at 17:53, Dr Fields James Bruce wrote: > On Mon, Jan 06, 2014 at 05:40:03PM -0500, Trond Myklebust wrote: >> >> On Jan 6, 2014, at 13:49, J. Bruce Fields wrote: >> >>> On Mon, Jan 06, 2014 at 05:33:22PM +0800, Kinglong Mee wrote: >>>> xs_setup_bc_tcp may return an existing xprt with non-NULL servername. >>>> xprt_create_transport should not kstrdup servername for it. >>>> Otherwise, those memory for servername will be leaked. >>> >>> OK. Applying to my tree if Trond has no objection. >> >> Actually. Why do we go through all this code at all if xs_setup_bc_tcp() returns args->bc_xprt->xpt_bc_xprt? I?m assuming that is the only case where xprt->servername != NULL, right? >> >> For instance, won?t calling INIT_WORK() be a source of problems? > > Huh. Looking at the history.... There used to be a > > if (test_and_set_bit(XPRT_INITIALIZED, &xprt->state)) > /* ->setup returned a pre-initialized xprt: */ > return xprt; > > here, but it got removed by 21de0a955f3af29fa1100d96f66e6adade89e77a > "SUNRPC: Clean up the slot table allocation", which looks otherwise > unrelated. Was that just some kind of rebasing mistake, or was there a > reason for that? I probably misunderstood that bc_xprt sends a fully initialized struct rpc_xprt. The obvious question if that is the case, is why we are calling xprt_create_transport() at all? If .bc_xprt->xpt_bc_xprt contains a fully initialized struct rpc_xprt, then just have rpc_create() do the honors. Better yet, create a svc_create_backchannel_client() helper that calls rpc_new_client() with the correct parameters. I really don?t like those rpc_create_args hacks that introduce fields that are completely private to nfsd. Trond