From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH 00/11] DMA sync errors
Date: Wed, 20 Jan 2010 16:18:05 -0800 (PST)
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From: Stephen Hemminger <shemminger@vyatta.com>
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 <shemminger@vyatta.com>
 ...
> --- 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;
>  }
>  

I think you have to enforce a perfect-fit match for the
non-SYNC cases.

check_sync() can pass in 'true' for a new bool argument "partial_ok"
added to hash_bucket_find() whereas check_unmap() can pass 'false'.

get_nr_mapped_entries() should pass 'false' as well.