From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751993AbcGGMqD (ORCPT ); Thu, 7 Jul 2016 08:46:03 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:40327 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751079AbcGGMpj (ORCPT ); Thu, 7 Jul 2016 08:45:39 -0400 X-IBM-Helo: d24dlp02.br.ibm.com X-IBM-MailFrom: mauricfo@linux.vnet.ibm.com X-IBM-RcptTo: linux-doc@vger.kernel.org;linux-kernel@vger.kernel.org From: Mauricio Faria de Oliveira To: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linuxppc-dev@lists.ozlabs.org Cc: Jonathan Corbet , Andrew Morton , Russell King , Keith Busch , Jens Axboe , Benjamin Herrenschmidt , Michael Ellerman Subject: [PATCH v2 1/3] dma: introduce DMA_ATTR_NO_WARN Date: Thu, 7 Jul 2016 09:45:07 -0300 X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1467895509-12194-1-git-send-email-mauricfo@linux.vnet.ibm.com> References: <1467895509-12194-1-git-send-email-mauricfo@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16070712-0020-0000-0000-0000021E05FC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16070712-0021-0000-0000-00002FFA08A7 Message-Id: <1467895509-12194-2-git-send-email-mauricfo@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-07_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1607070120 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Introduce the DMA_ATTR_NO_WARN attribute, and document it. Signed-off-by: Mauricio Faria de Oliveira --- Changelog: v2: - address warnings from checkpatch.pl (line wrapping and typos) Documentation/DMA-attributes.txt | 17 +++++++++++++++++ include/linux/dma-attrs.h | 1 + 2 files changed, 18 insertions(+) diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt index e8cf9cf..48150c6 100644 --- a/Documentation/DMA-attributes.txt +++ b/Documentation/DMA-attributes.txt @@ -126,3 +126,20 @@ means that we won't try quite as hard to get them. NOTE: At the moment DMA_ATTR_ALLOC_SINGLE_PAGES is only implemented on ARM, though ARM64 patches will likely be posted soon. + +DMA_ATTR_NO_WARN +---------------- + +This tells the DMA-mapping subsystem to suppress allocation failure reports +(similarly to __GFP_NOWARN). + +On some architectures allocation failures are reported with error messages +to the system logs. Although this can help to identify and debug problems, +drivers which handle failures (eg, retry later) have no problems with them, +and can actually flood the system logs with error messages that aren't any +problem at all, depending on the implementation of the retry mechanism. + +So, this provides a way for drivers to avoid those error messages on calls +where allocation failures are not a problem, and shouldn't bother the logs. + +NOTE: At the moment DMA_ATTR_NO_WARN is only implemented on PowerPC. diff --git a/include/linux/dma-attrs.h b/include/linux/dma-attrs.h index f3c5aea..0577389 100644 --- a/include/linux/dma-attrs.h +++ b/include/linux/dma-attrs.h @@ -19,6 +19,7 @@ enum dma_attr { DMA_ATTR_SKIP_CPU_SYNC, DMA_ATTR_FORCE_CONTIGUOUS, DMA_ATTR_ALLOC_SINGLE_PAGES, + DMA_ATTR_NO_WARN, DMA_ATTR_MAX, }; -- 1.8.3.1