From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754617AbbKXPDS (ORCPT ); Tue, 24 Nov 2015 10:03:18 -0500 Received: from mx2.suse.de ([195.135.220.15]:37913 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753528AbbKXPDO (ORCPT ); Tue, 24 Nov 2015 10:03:14 -0500 Message-ID: <56547C30.20800@suse.de> Date: Tue, 24 Nov 2015 16:03:12 +0100 From: Hannes Reinecke User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Arnd Bergmann , linux-scsi@vger.kernel.org CC: jbottomley@odin.com, martin.petersen@oracle.com, nico@fluxnic.net, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] scsi: use sector_div instead of do_div References: <24882658.08y4bWL6tn@wuerfel> In-Reply-To: <24882658.08y4bWL6tn@wuerfel> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/20/2015 05:38 PM, Arnd Bergmann wrote: > do_div is the wrong way to divide a sector_t, as it is less > efficient when sector_t is 32-bit wide. With the upcoming > do_div optimizations, the kernel starts warning about this: > > drivers/scsi/scsi_debug.c: In function 'dif_store': > include/asm-generic/div64.h:207:28: warning: comparison of distinct pointer types lacks a cast > > This changes the code to use sector_div instead, which always > produces optimal code. > > Signed-off-by: Arnd Bergmann > --- > Found on the ARM randconfig build today, after I merged Nico's patches > for linux-next > > diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c > index dfcc45bb03b1..ec622ba9864a 100644 > --- a/drivers/scsi/scsi_debug.c > +++ b/drivers/scsi/scsi_debug.c > @@ -678,7 +678,7 @@ static void *fake_store(unsigned long long lba) > > static struct sd_dif_tuple *dif_store(sector_t sector) > { > - sector = do_div(sector, sdebug_store_sectors); > + sector = sector_div(sector, sdebug_store_sectors); > > return dif_storep + sector; > } > @@ -2780,7 +2780,7 @@ static unsigned long lba_to_map_index(sector_t lba) > lba += scsi_debug_unmap_granularity - > scsi_debug_unmap_alignment; > } > - do_div(lba, scsi_debug_unmap_granularity); > + sector_div(lba, scsi_debug_unmap_granularity); > > return lba; > } > Reviewed-by: Hannes Reinecke Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) From mboxrd@z Thu Jan 1 00:00:00 1970 From: hare@suse.de (Hannes Reinecke) Date: Tue, 24 Nov 2015 16:03:12 +0100 Subject: [PATCH] scsi: use sector_div instead of do_div In-Reply-To: <24882658.08y4bWL6tn@wuerfel> References: <24882658.08y4bWL6tn@wuerfel> Message-ID: <56547C30.20800@suse.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 11/20/2015 05:38 PM, Arnd Bergmann wrote: > do_div is the wrong way to divide a sector_t, as it is less > efficient when sector_t is 32-bit wide. With the upcoming > do_div optimizations, the kernel starts warning about this: > > drivers/scsi/scsi_debug.c: In function 'dif_store': > include/asm-generic/div64.h:207:28: warning: comparison of distinct pointer types lacks a cast > > This changes the code to use sector_div instead, which always > produces optimal code. > > Signed-off-by: Arnd Bergmann > --- > Found on the ARM randconfig build today, after I merged Nico's patches > for linux-next > > diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c > index dfcc45bb03b1..ec622ba9864a 100644 > --- a/drivers/scsi/scsi_debug.c > +++ b/drivers/scsi/scsi_debug.c > @@ -678,7 +678,7 @@ static void *fake_store(unsigned long long lba) > > static struct sd_dif_tuple *dif_store(sector_t sector) > { > - sector = do_div(sector, sdebug_store_sectors); > + sector = sector_div(sector, sdebug_store_sectors); > > return dif_storep + sector; > } > @@ -2780,7 +2780,7 @@ static unsigned long lba_to_map_index(sector_t lba) > lba += scsi_debug_unmap_granularity - > scsi_debug_unmap_alignment; > } > - do_div(lba, scsi_debug_unmap_granularity); > + sector_div(lba, scsi_debug_unmap_granularity); > > return lba; > } > Reviewed-by: Hannes Reinecke Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare at suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N?rnberg GF: F. Imend?rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG N?rnberg)