[PATCH 08/17] crypto: skcipher - add the ability to abort a skcipher walk

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

After starting a skcipher walk, the only way to ensure that all
resources it has tied up are released is to complete it. In some
cases, it will be useful to be able to abort a walk cleanly after
it has started, so add this ability to the skcipher walk API.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 crypto/skcipher.c                  | 3 +++
 include/crypto/internal/skcipher.h | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/crypto/skcipher.c b/crypto/skcipher.c
index 5d836fc3df3e..973ab1c7dcca 100644
--- a/crypto/skcipher.c
+++ b/crypto/skcipher.c
@@ -140,6 +140,9 @@ int skcipher_walk_done(struct skcipher_walk *walk, int err)
 		goto already_advanced;
 	}
 
+	if (unlikely(!n))
+		goto finish;
+
 	scatterwalk_advance(&walk->in, n);
 	scatterwalk_advance(&walk->out, n);
 already_advanced:
diff --git a/include/crypto/internal/skcipher.h b/include/crypto/internal/skcipher.h
index d68faa5759ad..bc488173531f 100644
--- a/include/crypto/internal/skcipher.h
+++ b/include/crypto/internal/skcipher.h
@@ -148,6 +148,11 @@ int skcipher_walk_aead_decrypt(struct skcipher_walk *walk,
 			       struct aead_request *req, bool atomic);
 void skcipher_walk_complete(struct skcipher_walk *walk, int err);
 
+static inline void skcipher_walk_abort(struct skcipher_walk *walk)
+{
+	skcipher_walk_done(walk, walk->nbytes);
+}
+
 static inline void ablkcipher_request_complete(struct ablkcipher_request *req,
 					       int err)
 {
-- 
2.17.1