crypto: akcipher - pass instance to crypto_grab_akcipher()

Initializing a crypto_akcipher_spawn currently requires:

1. Set spawn->base.inst to point to the instance.
2. Call crypto_grab_akcipher().

But there's no reason for these steps to be separate, and in fact this
unneeded complication has caused at least one bug, the one fixed by
commit 6db43410179b ("crypto: adiantum - initialize crypto_spawn::inst")

So just make crypto_grab_akcipher() take the instance as an argument.

To keep the function call from getting too unwieldy due to this extra
argument, also introduce a 'mask' variable into pkcs1pad_create().

Signed-off-by: Eric Biggers <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

crypto/akcipher.c

···
 	.tfmsize = offsetof(struct crypto_akcipher, base),
 };
 
-int crypto_grab_akcipher(struct crypto_akcipher_spawn *spawn, const char *name,
-			 u32 type, u32 mask)
+int crypto_grab_akcipher(struct crypto_akcipher_spawn *spawn,
+			 struct crypto_instance *inst,
+			 const char *name, u32 type, u32 mask)
 {
+	spawn->base.inst = inst;
 	spawn->base.frontend = &crypto_akcipher_type;
 	return crypto_grab_spawn(&spawn->base, name, type, mask);
 }

crypto/rsa-pkcs1pad.c

···
 {
 	const struct rsa_asn1_template *digest_info;
 	struct crypto_attr_type *algt;
+	u32 mask;
 	struct akcipher_instance *inst;
 	struct pkcs1pad_inst_ctx *ctx;
 	struct crypto_akcipher_spawn *spawn;
···
 
 	if ((algt->type ^ CRYPTO_ALG_TYPE_AKCIPHER) & algt->mask)
 		return -EINVAL;
+
+	mask = crypto_requires_sync(algt->type, algt->mask);
 
 	rsa_alg_name = crypto_attr_alg_name(tb[1]);
 	if (IS_ERR(rsa_alg_name))
···
 	spawn = &ctx->spawn;
 	ctx->digest_info = digest_info;
 
-	crypto_set_spawn(&spawn->base, akcipher_crypto_instance(inst));
-	err = crypto_grab_akcipher(spawn, rsa_alg_name, 0,
-			crypto_requires_sync(algt->type, algt->mask));
+	err = crypto_grab_akcipher(spawn, akcipher_crypto_instance(inst),
+				   rsa_alg_name, 0, mask);
 	if (err)
 		goto out_free_inst;
 

include/crypto/internal/akcipher.h

···
 	return crypto_instance_ctx(akcipher_crypto_instance(inst));
 }
 
-static inline void crypto_set_akcipher_spawn(
-		struct crypto_akcipher_spawn *spawn,
-		struct crypto_instance *inst)
-{
-	crypto_set_spawn(&spawn->base, inst);
-}
-
-int crypto_grab_akcipher(struct crypto_akcipher_spawn *spawn, const char *name,
-		u32 type, u32 mask);
+int crypto_grab_akcipher(struct crypto_akcipher_spawn *spawn,
+			 struct crypto_instance *inst,
+			 const char *name, u32 type, u32 mask);
 
 static inline struct crypto_akcipher *crypto_spawn_akcipher(
 		struct crypto_akcipher_spawn *spawn)