From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rmDJv5Ll2zDqq1 for ; Fri, 8 Jul 2016 22:27:27 +1000 (AEST) Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u68COIVr097788 for ; Fri, 8 Jul 2016 08:27:25 -0400 Received: from e24smtp05.br.ibm.com (e24smtp05.br.ibm.com [32.104.18.26]) by mx0b-001b2d01.pphosted.com with ESMTP id 2415xntcad-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 08 Jul 2016 08:27:25 -0400 Received: from localhost by e24smtp05.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 8 Jul 2016 09:27:22 -0300 Received: from d24relay02.br.ibm.com (d24relay02.br.ibm.com [9.13.184.26]) by d24dlp01.br.ibm.com (Postfix) with ESMTP id F26D6352005F for ; Fri, 8 Jul 2016 08:27:02 -0400 (EDT) Received: from d24av01.br.ibm.com (d24av01.br.ibm.com [9.8.31.91]) by d24relay02.br.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u68CRKD934079032 for ; Fri, 8 Jul 2016 09:27:20 -0300 Received: from d24av01.br.ibm.com (localhost [127.0.0.1]) by d24av01.br.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u68CRJ2R014904 for ; Fri, 8 Jul 2016 09:27:20 -0300 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 v3 1/3] dma: introduce DMA_ATTR_NO_WARN Date: Fri, 8 Jul 2016 09:27:06 -0300 In-Reply-To: <1467980828-5282-1-git-send-email-mauricfo@linux.vnet.ibm.com> References: <1467980828-5282-1-git-send-email-mauricfo@linux.vnet.ibm.com> Message-Id: <1467980828-5282-2-git-send-email-mauricfo@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Introduce the DMA_ATTR_NO_WARN attribute, and document it. Signed-off-by: Mauricio Faria de Oliveira --- Changelog: v3: - dma: none. v2: - all: 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