From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754261Ab2IGSMi (ORCPT ); Fri, 7 Sep 2012 14:12:38 -0400 Received: from mail.linux-iscsi.org ([67.23.28.174]:43419 "EHLO linux-iscsi.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751342Ab2IGSMf (ORCPT ); Fri, 7 Sep 2012 14:12:35 -0400 Subject: Re: [PATCH 04/11] target: support zero-size allocation lengths in transport_kmap_data_sg From: "Nicholas A. Bellinger" To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, target-devel@vger.kernel.org, hch@lst.de, roland@kernel.org In-Reply-To: <1347031842-2531-5-git-send-email-pbonzini@redhat.com> References: <1347031842-2531-1-git-send-email-pbonzini@redhat.com> <1347031842-2531-5-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset="UTF-8" Date: Fri, 07 Sep 2012 11:12:33 -0700 Message-ID: <1347041553.4162.628.camel@haakon2.linux-iscsi.org> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2012-09-07 at 17:30 +0200, Paolo Bonzini wrote: > In order to support zero-size allocation lengths, do not assert > that we have a scatterlist until after checking cmd->data_length. > > But once we do this, we can have two cases of transport_kmap_data_sg > returning NULL: a zero-size allocation length, or an out-of-memory > condition. Report the latter using sense codes, so that the SCSI > command that triggered it will fail. > > Signed-off-by: Paolo Bonzini > --- Applied to master for-3.6. Nice work Paolo! > drivers/target/target_core_transport.c | 13 +++++++++---- > 1 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c > index 2e55aa9..8facb74 100644 > --- a/drivers/target/target_core_transport.c > +++ b/drivers/target/target_core_transport.c > @@ -2185,7 +2185,6 @@ void *transport_kmap_data_sg(struct se_cmd *cmd) > struct page **pages; > int i; > > - BUG_ON(!sg); > /* > * We need to take into account a possible offset here for fabrics like > * tcm_loop who may be using a contig buffer from the SCSI midlayer for > @@ -2193,13 +2192,17 @@ void *transport_kmap_data_sg(struct se_cmd *cmd) > */ > if (!cmd->t_data_nents) > return NULL; > - else if (cmd->t_data_nents == 1) > + > + BUG_ON(!sg); > + if (cmd->t_data_nents == 1) > return kmap(sg_page(sg)) + sg->offset; > > /* >1 page. use vmap */ > pages = kmalloc(sizeof(*pages) * cmd->t_data_nents, GFP_KERNEL); > - if (!pages) > + if (!pages) { > + cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; > return NULL; > + } > > /* convert sg[] to pages[] */ > for_each_sg(cmd->t_data_sg, sg, cmd->t_data_nents, i) { > @@ -2208,8 +2211,10 @@ void *transport_kmap_data_sg(struct se_cmd *cmd) > > cmd->t_data_vmap = vmap(pages, cmd->t_data_nents, VM_MAP, PAGE_KERNEL); > kfree(pages); > - if (!cmd->t_data_vmap) > + if (!cmd->t_data_vmap) { > + cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; > return NULL; > + } > > return cmd->t_data_vmap + cmd->t_data_sg[0].offset; > }