crypto: ahash - introduce crypto_grab_ahash()

Currently, ahash spawns are initialized by using ahash_attr_alg() or
crypto_find_alg() to look up the ahash algorithm, then calling
crypto_init_ahash_spawn().

This is different from how skcipher, aead, and akcipher spawns are
initialized (they use crypto_grab_*()), and for no good reason.  This
difference introduces unnecessary complexity.

The crypto_grab_*() functions used to have some problems, like not
holding a reference to the algorithm and requiring the caller to
initialize spawn->base.inst.  But those problems are fixed now.

So, let's introduce crypto_grab_ahash() so that we can convert all
templates to the same way of initializing their spawns.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/ahash.c

@@ -556,6 +556,15 @@ const struct crypto_type crypto_ahash_type = {
 };
 EXPORT_SYMBOL_GPL(crypto_ahash_type);
 
+int crypto_grab_ahash(struct crypto_ahash_spawn *spawn,
+		      struct crypto_instance *inst,
+		      const char *name, u32 type, u32 mask)
+{
+	spawn->base.frontend = &crypto_ahash_type;
+	return crypto_grab_spawn(&spawn->base, inst, name, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_grab_ahash);
+
 struct crypto_ahash *crypto_alloc_ahash(const char *alg_name, u32 type,
 					u32 mask)
 {

include/crypto/internal/hash.h

@@ -109,11 +109,21 @@ int crypto_init_ahash_spawn(struct crypto_ahash_spawn *spawn,
 			    struct hash_alg_common *alg,
 			    struct crypto_instance *inst);
 
+int crypto_grab_ahash(struct crypto_ahash_spawn *spawn,
+		      struct crypto_instance *inst,
+		      const char *name, u32 type, u32 mask);
+
 static inline void crypto_drop_ahash(struct crypto_ahash_spawn *spawn)
 {
 	crypto_drop_spawn(&spawn->base);
 }
 
+static inline struct hash_alg_common *crypto_spawn_ahash_alg(
+	struct crypto_ahash_spawn *spawn)
+{
+	return __crypto_hash_alg_common(spawn->base.alg);
+}
+
 struct hash_alg_common *ahash_attr_alg(struct rtattr *rta, u32 type, u32 mask);
 
 int crypto_register_shash(struct shash_alg *alg);