Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966783AbcCPPL4 (ORCPT ); Wed, 16 Mar 2016 11:11:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50811 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964860AbcCPPLz (ORCPT ); Wed, 16 Mar 2016 11:11:55 -0400 Subject: Re: [PATCH] qla2xxx: avoid maybe_uninitialized warning To: Arnd Bergmann , qla2xxx-upstream@qlogic.com, "James E.J. Bottomley" , "Martin K. Petersen" References: <1458078051-529344-1-git-send-email-arnd@arndb.de> <56E975B8.6040807@redhat.com> Cc: Nicholas Bellinger , Himanshu Madhani , Quinn Tran , Alexei Potashnik , Bart Van Assche , Swapnil Nagle , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org From: Tomas Henzl Message-ID: <56E977B7.1030607@redhat.com> Date: Wed, 16 Mar 2016 16:11:51 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <56E975B8.6040807@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3419 Lines: 72 On 16.3.2016 16:03, Tomas Henzl wrote: > On 15.3.2016 22:40, Arnd Bergmann wrote: >> The qlt_check_reserve_free_req() function produces an incorrect warning >> when CONFIG_PROFILE_ANNOTATED_BRANCHES is set: >> >> drivers/scsi/qla2xxx/qla_target.c: In function 'qlt_check_reserve_free_req': >> drivers/scsi/qla2xxx/qla_target.c:1887:3: error: 'cnt_in' may be used uninitialized in this function [-Werror=maybe-uninitialized] >> ql_dbg(ql_dbg_io, vha, 0x305a, >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> "qla_target(%d): There is no room in the request ring: vha->req->ring_index=%d, vha->req->cnt=%d, req_cnt=%d Req-out=%d Req-in=%d Req-Length=%d\n", >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> vha->vp_idx, vha->req->ring_index, >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> vha->req->cnt, req_cnt, cnt, cnt_in, vha->req->length); >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> drivers/scsi/qla2xxx/qla_target.c:1887:3: error: 'cnt' may be used uninitialized in this function [-Werror=maybe-uninitialized] >> >> The problem is that gcc fails to track the state of the condition across >> an annotated branch. >> >> This slightly rearranges the code to move the second if() block >> into the first one, to avoid the warning while retaining the >> behavior of the code. > When the first 'if' is true the vha->req->ring_index gets a new value > assigned - so it could be possible that the second 'if' wont be true any more. > The code should not be merged into that single 'if', or am I missing something? Oh, I haven't noticed that the second if actually remained in place - please ignore my previous comments. > > tomash > >> Signed-off-by: Arnd Bergmann >> --- >> drivers/scsi/qla2xxx/qla_target.c | 16 +++++++++------- >> 1 file changed, 9 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c >> index 985231900aca..8a44d1541eb4 100644 >> --- a/drivers/scsi/qla2xxx/qla_target.c >> +++ b/drivers/scsi/qla2xxx/qla_target.c >> @@ -1881,15 +1881,17 @@ static int qlt_check_reserve_free_req(struct scsi_qla_host *vha, >> else >> vha->req->cnt = vha->req->length - >> (vha->req->ring_index - cnt); >> - } >> >> - if (unlikely(vha->req->cnt < (req_cnt + 2))) { >> - ql_dbg(ql_dbg_io, vha, 0x305a, >> - "qla_target(%d): There is no room in the request ring: vha->req->ring_index=%d, vha->req->cnt=%d, req_cnt=%d Req-out=%d Req-in=%d Req-Length=%d\n", >> - vha->vp_idx, vha->req->ring_index, >> - vha->req->cnt, req_cnt, cnt, cnt_in, vha->req->length); >> - return -EAGAIN; >> + if (unlikely(vha->req->cnt < (req_cnt + 2))) { >> + ql_dbg(ql_dbg_io, vha, 0x305a, >> + "qla_target(%d): There is no room in the request ring: vha->req->ring_index=%d, vha->req->cnt=%d, req_cnt=%d Req-out=%d Req-in=%d Req-Length=%d\n", >> + vha->vp_idx, vha->req->ring_index, >> + vha->req->cnt, req_cnt, cnt, cnt_in, >> + vha->req->length); >> + return -EAGAIN; >> + } >> } >> + >> vha->req->cnt -= req_cnt; >> >> return 0; > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html