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>
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index cf90620..7d2f0b3 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -913,6 +913,9 @@
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 @@
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 @@
out:
put_hash_bucket(bucket, &flags);
-
}
void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,