crypto: ahash - Add init_tfm/exit_tfm

This patch adds the type-safe init_tfm/exit_tfm functions to the
ahash interface.  This is meant to replace the unsafe cra_init and
cra_exit interface.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/ahash.c

@@ -444,6 +444,14 @@ static int ahash_def_finup(struct ahash_request *req)
 	return ahash_def_finup_finish1(req, err);
 }
 
+static void crypto_ahash_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_ahash *hash = __crypto_ahash_cast(tfm);
+	struct ahash_alg *alg = crypto_ahash_alg(hash);
+
+	alg->exit_tfm(hash);
+}
+
 static int crypto_ahash_init_tfm(struct crypto_tfm *tfm)
 {
 	struct crypto_ahash *hash = __crypto_ahash_cast(tfm);
@@ -467,7 +475,10 @@ static int crypto_ahash_init_tfm(struct crypto_tfm *tfm)
 		ahash_set_needkey(hash);
 	}
 
-	return 0;
+	if (alg->exit_tfm)
+		tfm->exit = crypto_ahash_exit_tfm;
+
+	return alg->init_tfm ? alg->init_tfm(hash) : 0;
 }
 
 static unsigned int crypto_ahash_extsize(struct crypto_alg *alg)

include/crypto/hash.h

@@ -123,6 +123,17 @@ struct ahash_request {
  *	    data so the transformation can continue from this point onward. No
  *	    data processing happens at this point. Driver must not use
  *	    req->result.
+ * @init_tfm: Initialize the cryptographic transformation object.
+ *	      This function is called only once at the instantiation
+ *	      time, right after the transformation context was
+ *	      allocated. In case the cryptographic hardware has
+ *	      some special requirements which need to be handled
+ *	      by software, this function shall check for the precise
+ *	      requirement of the transformation and put any software
+ *	      fallbacks in place.
+ * @exit_tfm: Deinitialize the cryptographic transformation object.
+ *	      This is a counterpart to @init_tfm, used to remove
+ *	      various changes set in @init_tfm.
  * @halg: see struct hash_alg_common
  */
 struct ahash_alg {
@@ -135,6 +146,8 @@ struct ahash_alg {
 	int (*import)(struct ahash_request *req, const void *in);
 	int (*setkey)(struct crypto_ahash *tfm, const u8 *key,
 		      unsigned int keylen);
+	int (*init_tfm)(struct crypto_ahash *tfm);
+	void (*exit_tfm)(struct crypto_ahash *tfm);
 
 	struct hash_alg_common halg;
 };