The patch titled
Subject: dma-mapping: introduce the DMA_ATTR_NO_WARN attribute
has been added to the -mm tree. Its filename is
dma-mapping-introduce-the-dma_attr_no_warn-attribute.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/dma-mapping-introduce-the-dma_attr_no_warn-attribute.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/dma-mapping-introduce-the-dma_attr_no_warn-attribute.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Mauricio Faria de Oliveira <mauricfo@xxxxxxxxxxxxxxxxxx>
Subject: dma-mapping: introduce the DMA_ATTR_NO_WARN attribute
Introduce the DMA_ATTR_NO_WARN attribute, and document it.
Link: http://lkml.kernel.org/r/1470092390-25451-2-git-send-email-mauricfo@xxxxxxxxxxxxxxxxxx
Signed-off-by: Mauricio Faria de Oliveira <mauricfo@xxxxxxxxxxxxxxxxxx>
Cc: Keith Busch <keith.busch@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/DMA-attributes.txt | 17 +++++++++++++++++
include/linux/dma-mapping.h | 5 +++++
2 files changed, 22 insertions(+)
diff -puN Documentation/DMA-attributes.txt~dma-mapping-introduce-the-dma_attr_no_warn-attribute Documentation/DMA-attributes.txt
--- a/Documentation/DMA-attributes.txt~dma-mapping-introduce-the-dma_attr_no_warn-attribute
+++ a/Documentation/DMA-attributes.txt
@@ -126,3 +126,20 @@ means that we won't try quite as hard to
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 -puN include/linux/dma-mapping.h~dma-mapping-introduce-the-dma_attr_no_warn-attribute include/linux/dma-mapping.h
--- a/include/linux/dma-mapping.h~dma-mapping-introduce-the-dma_attr_no_warn-attribute
+++ a/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.
_
Patches currently in -mm which might be from mauricfo@xxxxxxxxxxxxxxxxxx are
dma-mapping-introduce-the-dma_attr_no_warn-attribute.patch
powerpc-implement-the-dma_attr_no_warn-attribute.patch
nvme-use-the-dma_attr_no_warn-attribute.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
