On Thu, Apr 27, 2017 at 09:45:57AM -0600, Logan Gunthorpe wrote:

On 26/04/17 09:56 PM, Herbert Xu wrote:

quoted

On Tue, Apr 25, 2017 at 12:20:54PM -0600, Logan Gunthorpe wrote:

quoted

Very straightforward conversion to the new function in the caam driver
and shash library.

Signed-off-by: Logan Gunthorpe <logang-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
Cc: Herbert Xu <redacted>
Cc: "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
---
 crypto/shash.c                | 9 ++++++---
 drivers/crypto/caam/caamalg.c | 8 +++-----
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/crypto/shash.c b/crypto/shash.c
index 5e31c8d..5914881 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c

@@ -283,10 +283,13 @@ int shash_ahash_digest(struct ahash_request *req, struct shash_desc *desc)
 	if (nbytes < min(sg->length, ((unsigned int)(PAGE_SIZE)) - offset)) {
 		void *data;
 
-		data = kmap_atomic(sg_page(sg));
-		err = crypto_shash_digest(desc, data + offset, nbytes,
+		data = sg_map(sg, 0, SG_KMAP_ATOMIC);
+		if (IS_ERR(data))
+			return PTR_ERR(data);
+
+		err = crypto_shash_digest(desc, data, nbytes,
 					  req->result);
-		kunmap_atomic(data);
+		sg_unmap(sg, data, 0, SG_KMAP_ATOMIC);
 		crypto_yield(desc->flags);
 	} else
 		err = crypto_shash_init(desc) ?:

Nack.  This is an optimisation for the special case of a single
SG list entry.  In fact in the common case the kmap_atomic should
disappear altogether in the no-highmem case.  So replacing it
with sg_map is not acceptable.

What you seem to have missed is that sg_map is just a thin wrapper
around kmap_atomic. Perhaps with a future check for a mappable page.
This change should have zero impact on performance.

You are right.  Indeed the existing code looks buggy as they
don't take sg->offset into account when doing the kmap.  Could
you send me some patches that fix these problems first so that
they can be easily backported?

Thanks,
-- 
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt