From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH] sg: remove unreachable code in SET_FORCE_LOW_DMA Date: Wed, 1 Feb 2017 14:00:48 +0100 Message-ID: <20170201130048.GA5125@lst.de> References: <1485948399-83339-1-git-send-email-hare@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from verein.lst.de ([213.95.11.211]:35144 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751127AbdBANAu (ORCPT ); Wed, 1 Feb 2017 08:00:50 -0500 Content-Disposition: inline In-Reply-To: <1485948399-83339-1-git-send-email-hare@suse.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Hannes Reinecke Cc: "Martin K. Petersen" , James Bottomley , Christoph Hellwig , linux-scsi@vger.kernel.org, Hannes Reinecke On Wed, Feb 01, 2017 at 12:26:39PM +0100, Hannes Reinecke wrote: > The low_dma value is always '1' in that branch, so the remaining > 'if' statement can never be reached. > > > Signed-off-by: Hannes Reinecke > --- > drivers/scsi/sg.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) > > diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c > index dbe5b4b..652b934 100644 > --- a/drivers/scsi/sg.c > +++ b/drivers/scsi/sg.c > @@ -890,14 +890,9 @@ static int max_sectors_bytes(struct request_queue *q) > result = get_user(val, ip); > if (result) > return result; > - if (val) { > + if (val) > sfp->low_dma = 1; > - if ((0 == sfp->low_dma) && (0 == sg_res_in_use(sfp))) { > - val = (int) sfp->reserve.bufflen; > - sg_remove_scat(sfp, &sfp->reserve); > - sg_build_reserve(sfp, val); > - } > - } else { > + else { I think the proper fix is to check sfp->low_dma for 0 before updating it, at least that seems to be the intent here.