On Wed, 17 Jun 2015 17:34:02 +0200
Boris Brezillon [off-list ref] wrote:

On Wed, 17 Jun 2015 23:08:08 +0800
Herbert Xu [off-list ref] wrote:

quoted

On Wed, Jun 17, 2015 at 03:32:02PM +0200, Boris Brezillon wrote:

quoted

Hi Herbert,

I send you this patch alone so that you can verify I'm now properly
manipulating the SG list. Once I have your confirmation I'll send
the whole series again and annoy all the people in Cc one more time
;-).

Thanks.  The only problem that I can see is the fact you're not
checking for req->src == req->dst.  If they're equal then you must
not map it twice.  Instead it should be mapped as DMA_BIDIRECTIONAL.

I can check for that too, but note that it doesn't prevent one from
providing different scatterlist structures pointing to the same memory
region.

Actually, I don't know if it's a problem or not, so if it's not, please
ignore my comment.

This being said, checking for req->src == req->dst should fix the case
where dst and src are pointing to the same scatterlist, which is a good
start.

Here is an incremental patch [1], please let me know if something else
is missing.

Thanks,

Boris

[1]http://code.bulix.org/x8mz8x-88568


-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com