From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (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 3s3FKj5SC7zDqQL for ; Tue, 2 Aug 2016 09:05:13 +1000 (AEST) Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u71N48kJ136800 for ; Mon, 1 Aug 2016 19:05:11 -0400 Received: from e24smtp04.br.ibm.com (e24smtp04.br.ibm.com [32.104.18.25]) by mx0a-001b2d01.pphosted.com with ESMTP id 24grracq9s-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 01 Aug 2016 19:05:11 -0400 Received: from localhost by e24smtp04.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 1 Aug 2016 20:05:08 -0300 Received: from d24relay03.br.ibm.com (d24relay03.br.ibm.com [9.13.184.25]) by d24dlp01.br.ibm.com (Postfix) with ESMTP id A81DB3520070 for ; Mon, 1 Aug 2016 19:04:47 -0400 (EDT) Received: from d24av01.br.ibm.com (d24av01.br.ibm.com [9.8.31.91]) by d24relay03.br.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u71N57Z69568534 for ; Mon, 1 Aug 2016 20:05:07 -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 u71N56uP023864 for ; Mon, 1 Aug 2016 20:05:07 -0300 From: Mauricio Faria de Oliveira To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH 1/3] dma-mapping: introduce the DMA_ATTR_NO_WARN attribute Date: Mon, 1 Aug 2016 20:05:04 -0300 In-Reply-To: <1470092706-28075-1-git-send-email-mauricfo@linux.vnet.ibm.com> References: <1470092706-28075-1-git-send-email-mauricfo@linux.vnet.ibm.com> Message-Id: <1470092706-28075-2-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 --- Documentation/DMA-attributes.txt | 17 +++++++++++++++++ include/linux/dma-mapping.h | 5 +++++ 2 files changed, 22 insertions(+) diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt index 2d455a5..98bf7ac 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-mapping.h b/include/linux/dma-mapping.h index 66533e1..6efbd27 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -56,6 +56,11 @@ * that gives better TLB efficiency. */ #define DMA_ATTR_ALLOC_SINGLE_PAGES (1UL << 7) +/* + * DMA_ATTR_NO_WARN: This tells the DMA-mapping subsystem to suppress + * allocation failure reports (similarly to __GFP_NOWARN). + */ +#define DMA_ATTR_NO_WARN (1UL << 8) /* * A dma_addr_t can hold any valid DMA or bus address for the platform. -- 1.8.3.1