[PATCH v2 1/3] dma: introduce DMA_ATTR_NO_WARN
From: Mauricio Faria de Oliveira <hidden>
Date: 2016-07-07 12:46:03
Also in:
linux-nvme, lkml
Subsystem:
documentation, the rest · Maintainers:
Jonathan Corbet, Linus Torvalds
Introduce the DMA_ATTR_NO_WARN attribute, and document it. Signed-off-by: Mauricio Faria de Oliveira <redacted> --- 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