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Commit 42d53b4f authored by Krzysztof Halasa's avatar Krzysztof Halasa Committed by Linus Torvalds
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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: default avatarKrzysztof 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e992cd9b

lib/dma-debug.c

+3 −4
Original line number Diff line number Diff line
@@ -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,