Subject: Re: [PATCH 00/11] DMA sync errors

From: Stephen Hemminger <[email-masked]>
Date: Wed, 20 Jan 2010 15:28:32 -0800

This should fix the dma-debug API code (and documentation), to
avoid false positives when sync is done on a partial map.

Signed-off-by: Stephen Hemminger <[email-masked]>

--- a/Documentation/DMA-API.txt	2010-01-20 15:17:01.390143729 -0800
+++ b/Documentation/DMA-API.txt	2010-01-20 15:18:48.967875255 -0800
@@ -377,9 +377,10 @@ void
 pci_dma_sync_sg(struct pci_dev *hwdev, struct scatterlist *sg,
 		       int nelems, int direction)
 
-Synchronise a single contiguous or scatter/gather mapping.  All the
-parameters must be the same as those passed into the single mapping
-API.
+Synchronise a single contiguous or scatter/gather mapping.  The
+device and handle must be the same as those passed into the single mapping
+API. The size can be less than the original mapping if only part
+of the mapping needs to be accessed.
 
 Notes:  You must do this:
 
--- a/lib/dma-debug.c	2010-01-20 15:22:55.919519883 -0800
+++ b/lib/dma-debug.c	2010-01-20 15:26:31.648895638 -0800
@@ -285,11 +285,9 @@ static struct dma_debug_entry *hash_buck
 	}
 
 	/*
-	 * If we have multiple matches but no perfect-fit, just return
-	 * NULL.
+	 * If we have multiple matches but no perfect-fit
+	 * return best value and let caller deal with it.
 	 */
-	ret = (matches == 1) ? ret : NULL;
-
 	return ret;
 }