From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758235Ab3KNWyk (ORCPT ); Thu, 14 Nov 2013 17:54:40 -0500 Received: from mail.tpi.com ([74.45.170.26]:48221 "EHLO mail.tpi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751951Ab3KNWyg (ORCPT ); Thu, 14 Nov 2013 17:54:36 -0500 Message-ID: <528554AC.5080607@canonical.com> Date: Thu, 14 Nov 2013 14:54:36 -0800 From: Tim Gardner User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Konrad Rzeszutek Wilk , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org CC: Boris Ostrovsky , David Vrabel , "roger.pau@citrix.com" Subject: Re: [PATCH 3.13-rc1] xen-blkfront: Silence pfn maybe-uninitialized warning References: <1384464592-35970-1-git-send-email-tim.gardner@canonical.com> <17a2e4ab-d2dc-4bcc-a0fc-1eb1172876e5@email.android.com> In-Reply-To: <17a2e4ab-d2dc-4bcc-a0fc-1eb1172876e5@email.android.com> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/14/2013 02:24 PM, Konrad Rzeszutek Wilk wrote: > Tim Gardner wrote: >> pfn cannot actually be used unless (!info->feature_persistent), nor >> is pfn accessed in get_grant() unless (!info->feature_persistent), >> but silence this warning anyway. gcc-4.8 >> >> drivers/block/xen-blkfront.c: In function 'do_blkif_request': >> drivers/block/xen-blkfront.c:508:20: warning: 'pfn' may be used >> uninitialized in this function [-Wmaybe-uninitialized] >> gnt_list_entry = get_grant(&gref_head, pfn, info); ^ >> drivers/block/xen-blkfront.c:492:19: note: 'pfn' was declared here >> unsigned long pfn; >> >> Cc: Konrad Rzeszutek Wilk Cc: Boris >> Ostrovsky Cc: David Vrabel >> Signed-off-by: Tim Gardner >> --- drivers/block/xen-blkfront.c | 2 >> +- 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/block/xen-blkfront.c >> b/drivers/block/xen-blkfront.c index 432db1b..5f926de 100644 --- >> a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c >> @@ -489,7 +489,7 @@ static int blkif_queue_request(struct request >> *req) >> >> if ((ring_req->operation == BLKIF_OP_INDIRECT) && (i % >> SEGS_PER_INDIRECT_FRAME == 0)) { - unsigned long pfn; + >> unsigned long uninitialized_var(pfn); >> >> if (segments) kunmap_atomic(segments); > > I have a similar patch from Roger that sets pfn=0. > > Roger could you repost your patch please or if you feel that this > patch makes sense then comment on it? > > Thanks. > The advantage of uninitialized_var() is that it doesn't actually generate any code (or so it says in the header). rtg -- Tim Gardner tim.gardner@canonical.com