From 42d53b4ff7d61487d18274ebdf1f70c1aef6f122 Mon Sep 17 00:00:00 2001
From: Krzysztof Halasa <khc@pm.waw.pl>
Date: Fri, 8 Jan 2010 14:42:36 -0800
Subject: [PATCH] dma-debug: allow DMA_BIDIRECTIONAL mappings to be synced with
DMA_FROM_DEVICE and
There is no need to perform full BIDIR sync (copying the buffers in case
of swiotlb and similar schemes) if we know that the owner (CPU or device)
hasn't altered the data.
Addresses the false-positive reported at
http://bugzilla.kernel.org/show_bug.cgi?id=14169
Signed-off-by: Krzysztof Halasa <khc@pm.waw.pl>
Cc: David Miller <davem@davemloft.net>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
lib/dma-debug.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index cf906201aecf..7d2f0b33e5a8 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -913,6 +913,9 @@ static void check_sync(struct device *dev,
ref->size);
}
+ if (entry->direction == DMA_BIDIRECTIONAL)
+ goto out;
+
if (ref->direction != entry->direction) {
err_printk(dev, entry, "DMA-API: device driver syncs "
"DMA memory with different direction "
@@ -923,9 +926,6 @@ static void check_sync(struct device *dev,
dir2name[ref->direction]);
}
- if (entry->direction == DMA_BIDIRECTIONAL)
- goto out;
-
if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
!(ref->direction == DMA_TO_DEVICE))
err_printk(dev, entry, "DMA-API: device driver syncs "
@@ -948,7 +948,6 @@ static void check_sync(struct device *dev,
out:
put_hash_bucket(bucket, &flags);
-
}
void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
--
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