crypto: hash - add support for new way of freeing instances

Add support to shash and ahash for the new way of freeing instances
(already used for skcipher, aead, and akcipher) where a ->free() method
is installed to the instance struct itself.  These methods are more
strongly-typed than crypto_template::free(), which they replace.

This will allow removing support for the old way of freeing instances.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/ahash.c

@@ -511,6 +511,18 @@ static unsigned int crypto_ahash_extsize(struct crypto_alg *alg)
 	return crypto_alg_extsize(alg);
 }
 
+static void crypto_ahash_free_instance(struct crypto_instance *inst)
+{
+	struct ahash_instance *ahash = ahash_instance(inst);
+
+	if (!ahash->free) {
+		inst->tmpl->free(inst);
+		return;
+	}
+
+	ahash->free(ahash);
+}
+
 #ifdef CONFIG_NET
 static int crypto_ahash_report(struct sk_buff *skb, struct crypto_alg *alg)
 {
@@ -547,6 +559,7 @@ static void crypto_ahash_show(struct seq_file *m, struct crypto_alg *alg)
 static const struct crypto_type crypto_ahash_type = {
 	.extsize = crypto_ahash_extsize,
 	.init_tfm = crypto_ahash_init_tfm,
+	.free = crypto_ahash_free_instance,
 #ifdef CONFIG_PROC_FS
 	.show = crypto_ahash_show,
 #endif

crypto/shash.c

@@ -423,6 +423,18 @@ static int crypto_shash_init_tfm(struct crypto_tfm *tfm)
 	return 0;
 }
 
+static void crypto_shash_free_instance(struct crypto_instance *inst)
+{
+	struct shash_instance *shash = shash_instance(inst);
+
+	if (!shash->free) {
+		inst->tmpl->free(inst);
+		return;
+	}
+
+	shash->free(shash);
+}
+
 #ifdef CONFIG_NET
 static int crypto_shash_report(struct sk_buff *skb, struct crypto_alg *alg)
 {
@@ -459,6 +471,7 @@ static void crypto_shash_show(struct seq_file *m, struct crypto_alg *alg)
 static const struct crypto_type crypto_shash_type = {
 	.extsize = crypto_alg_extsize,
 	.init_tfm = crypto_shash_init_tfm,
+	.free = crypto_shash_free_instance,
 #ifdef CONFIG_PROC_FS
 	.show = crypto_shash_show,
 #endif

include/crypto/internal/hash.h

@@ -30,6 +30,7 @@ struct crypto_hash_walk {
 };
 
 struct ahash_instance {
+	void (*free)(struct ahash_instance *inst);
 	union {
 		struct {
 			char head[offsetof(struct ahash_alg, halg.base)];
@@ -40,6 +41,7 @@ struct ahash_instance {
 };
 
 struct shash_instance {
+	void (*free)(struct shash_instance *inst);
 	union {
 		struct {
 			char head[offsetof(struct shash_alg, base)];