Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755182AbdDROOU convert rfc822-to-8bit (ORCPT ); Tue, 18 Apr 2017 10:14:20 -0400 Received: from smtp-out4.electric.net ([192.162.216.189]:53260 "EHLO smtp-out4.electric.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751456AbdDROOR (ORCPT ); Tue, 18 Apr 2017 10:14:17 -0400 From: David Laight To: "'Logan Gunthorpe'" , Christoph Hellwig , "Martin K. Petersen" , Sagi Grimberg , Jens Axboe , Tejun Heo , Greg Kroah-Hartman , Dan Williams , Ross Zwisler , Matthew Wilcox , Sumit Semwal , Ming Lin , "linux-kernel@vger.kernel.org" , "linux-crypto@vger.kernel.org" , "linux-media@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "linaro-mm-sig@lists.linaro.org" , "intel-gfx@lists.freedesktop.org" , "linux-raid@vger.kernel.org" , "linux-mmc@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "linux-nvdimm@lists.01.org" , "linux-scsi@vger.kernel.org" , "fcoe-devel@open-fcoe.org" , "open-iscsi@googlegroups.com" , "megaraidlinux.pdl@broadcom.com" , "sparmaintainer@unisys.com" , "devel@driverdev.osuosl.org" , "target-devel@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-rdma@vger.kernel.org" , "rds-devel@oss.oracle.com" CC: Steve Wise , Stephen Bates Subject: RE: [PATCH 16/22] xen-blkfront: Make use of the new sg_map helper function Thread-Topic: [PATCH 16/22] xen-blkfront: Make use of the new sg_map helper function Thread-Index: AQHStKM3eJ0Ts5AnY0atMk/FWB1DlKHLMmXg Date: Tue, 18 Apr 2017 14:13:59 +0000 Message-ID: <063D6719AE5E284EB5DD2968C1650D6DCFFD3CD7@AcuExch.aculab.com> References: <1492121135-4437-1-git-send-email-logang@deltatee.com> <1492121135-4437-17-git-send-email-logang@deltatee.com> In-Reply-To: <1492121135-4437-17-git-send-email-logang@deltatee.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.202.99.200] Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Outbound-IP: 213.249.233.130 X-Env-From: David.Laight@ACULAB.COM X-Proto: esmtps X-Revdns: X-HELO: AcuExch.aculab.com X-TLS: TLSv1:AES128-SHA:128 X-Authenticated_ID: X-PolicySMART: 3396946, 3397078 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1381 Lines: 41 From: Logan Gunthorpe > Sent: 13 April 2017 23:05 > Straightforward conversion to the new helper, except due to > the lack of error path, we have to warn if unmapable memory > is ever present in the sgl. > > Signed-off-by: Logan Gunthorpe > --- > drivers/block/xen-blkfront.c | 33 +++++++++++++++++++++++++++------ > 1 file changed, 27 insertions(+), 6 deletions(-) > > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c > index 5067a0a..7dcf41d 100644 > --- a/drivers/block/xen-blkfront.c > +++ b/drivers/block/xen-blkfront.c > @@ -807,8 +807,19 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri > BUG_ON(sg->offset + sg->length > PAGE_SIZE); > > if (setup.need_copy) { > - setup.bvec_off = sg->offset; > - setup.bvec_data = kmap_atomic(sg_page(sg)); > + setup.bvec_off = 0; > + setup.bvec_data = sg_map(sg, SG_KMAP_ATOMIC); > + if (IS_ERR(setup.bvec_data)) { > + /* > + * This should really never happen unless > + * the code is changed to use memory that is > + * not mappable in the sg. Seeing there is a > + * questionable error path out of here, > + * we WARN. > + */ > + WARN(1, "Non-mappable memory used in sg!"); > + return 1; > + } ... Perhaps add a flag to mark failure as 'unexpected' and trace (and panic?) inside sg_map(). David