crypto: shash - Add shash_instance

This patch adds shash_instance and the associated alloc/free
functions.  This is meant to be an instance that with a shash
algorithm under it.  Note that the instance itself doesn't have
to be shash.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/shash.c

@@ -502,5 +502,12 @@ int crypto_unregister_shash(struct shash_alg *alg)
 }
 EXPORT_SYMBOL_GPL(crypto_unregister_shash);
 
+void shash_free_instance(struct crypto_instance *inst)
+{
+	crypto_drop_spawn(crypto_instance_ctx(inst));
+	kfree(shash_instance(inst));
+}
+EXPORT_SYMBOL_GPL(shash_free_instance);
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Synchronous cryptographic hash type");

include/crypto/internal/hash.h

@@ -34,6 +34,10 @@ struct crypto_hash_walk {
 	unsigned int flags;
 };
 
+struct shash_instance {
+	struct shash_alg alg;
+};
+
 extern const struct crypto_type crypto_ahash_type;
 
 int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err);
@@ -46,6 +50,8 @@ int crypto_hash_walk_first_compat(struct hash_desc *hdesc,
 int crypto_register_shash(struct shash_alg *alg);
 int crypto_unregister_shash(struct shash_alg *alg);
 
+void shash_free_instance(struct crypto_instance *inst);
+
 static inline void *crypto_ahash_ctx(struct crypto_ahash *tfm)
 {
 	return crypto_tfm_ctx(&tfm->base);
@@ -80,5 +86,25 @@ static inline void *crypto_shash_ctx(struct crypto_shash *tfm)
 	return crypto_tfm_ctx(&tfm->base);
 }
 
+static inline struct crypto_instance *shash_crypto_instance(
+	struct shash_instance *inst)
+{
+	return container_of(&inst->alg.base, struct crypto_instance, alg);
+}
+
+static inline struct shash_instance *shash_instance(
+	struct crypto_instance *inst)
+{
+	return container_of(__crypto_shash_alg(&inst->alg),
+			    struct shash_instance, alg);
+}
+
+static inline struct shash_instance *shash_alloc_instance(
+	const char *name, struct crypto_alg *alg)
+{
+	return crypto_alloc_instance2(name, alg,
+				      sizeof(struct shash_alg) - sizeof(*alg));
+}
+
 #endif	/* _CRYPTO_INTERNAL_HASH_H */