crypto: ahash - optimize performance when wrapping shash

The "ahash" API provides access to both CPU-based and hardware offload-
based implementations of hash algorithms.  Typically the former are
implemented as "shash" algorithms under the hood, while the latter are
implemented as "ahash" algorithms.  The "ahash" API provides access to
both.  Various kernel subsystems use the ahash API because they want to
support hashing hardware offload without using a separate API for it.

Yet, the common case is that a crypto accelerator is not actually being
used, and ahash is just wrapping a CPU-based shash algorithm.

This patch optimizes the ahash API for that common case by eliminating
the extra indirect call for each ahash operation on top of shash.

It also fixes the double-counting of crypto stats in this scenario
(though CONFIG_CRYPTO_STATS should *not* be enabled by anyone interested
in performance anyway...), and it eliminates redundant checking of
CRYPTO_TFM_NEED_KEY.  As a bonus, it also shrinks struct crypto_ahash.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/hash.h

@@ -12,6 +12,16 @@
 
 #include "internal.h"
 
+static inline struct crypto_istat_hash *hash_get_stat(
+	struct hash_alg_common *alg)
+{
+#ifdef CONFIG_CRYPTO_STATS
+	return &alg->stat;
+#else
+	return NULL;
+#endif
+}
+
 static inline int crypto_hash_report_stat(struct sk_buff *skb,
 					  struct crypto_alg *alg,
 					  const char *type)

crypto/shash.c

@@ -23,7 +23,13 @@ static inline struct crypto_istat_hash *shash_get_stat(struct shash_alg *alg)
 
 static inline int crypto_shash_errstat(struct shash_alg *alg, int err)
 {
-	return crypto_hash_errstat(&alg->halg, err);
+	if (!IS_ENABLED(CONFIG_CRYPTO_STATS))
+		return err;
+
+	if (err && err != -EINPROGRESS && err != -EBUSY)
+		atomic64_inc(&shash_get_stat(alg)->err_cnt);
+
+	return err;
 }
 
 int shash_no_setkey(struct crypto_shash *tfm, const u8 *key,

include/crypto/hash.h

@@ -250,16 +250,7 @@ struct shash_alg {
 #undef HASH_ALG_COMMON_STAT
 
 struct crypto_ahash {
-	int (*init)(struct ahash_request *req);
-	int (*update)(struct ahash_request *req);
-	int (*final)(struct ahash_request *req);
-	int (*finup)(struct ahash_request *req);
-	int (*digest)(struct ahash_request *req);
-	int (*export)(struct ahash_request *req, void *out);
-	int (*import)(struct ahash_request *req, const void *in);
-	int (*setkey)(struct crypto_ahash *tfm, const u8 *key,
-		      unsigned int keylen);
-
+	bool using_shash; /* Underlying algorithm is shash, not ahash */
 	unsigned int statesize;
 	unsigned int reqsize;
 	struct crypto_tfm base;
@@ -513,10 +504,7 @@ int crypto_ahash_digest(struct ahash_request *req);
  *
  * Return: 0 if the export was successful; < 0 if an error occurred
  */
-static inline int crypto_ahash_export(struct ahash_request *req, void *out)
-{
-	return crypto_ahash_reqtfm(req)->export(req, out);
-}
+int crypto_ahash_export(struct ahash_request *req, void *out);
 
 /**
  * crypto_ahash_import() - import message digest state
@@ -529,15 +517,7 @@ static inline int crypto_ahash_export(struct ahash_request *req, void *out)
  *
  * Return: 0 if the import was successful; < 0 if an error occurred
  */
-static inline int crypto_ahash_import(struct ahash_request *req, const void *in)
-{
-	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
-
-	if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
-		return -ENOKEY;
-
-	return tfm->import(req, in);
-}
+int crypto_ahash_import(struct ahash_request *req, const void *in);
 
 /**
  * crypto_ahash_init() - (re)initialize message digest handle
@@ -550,36 +530,7 @@ static inline int crypto_ahash_import(struct ahash_request *req, const void *in)
  *
  * Return: see crypto_ahash_final()
  */
-static inline int crypto_ahash_init(struct ahash_request *req)
-{
-	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
-
-	if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
-		return -ENOKEY;
-
-	return tfm->init(req);
-}
-
-static inline struct crypto_istat_hash *hash_get_stat(
-	struct hash_alg_common *alg)
-{
-#ifdef CONFIG_CRYPTO_STATS
-	return &alg->stat;
-#else
-	return NULL;
-#endif
-}
-
-static inline int crypto_hash_errstat(struct hash_alg_common *alg, int err)
-{
-	if (!IS_ENABLED(CONFIG_CRYPTO_STATS))
-		return err;
-
-	if (err && err != -EINPROGRESS && err != -EBUSY)
-		atomic64_inc(&hash_get_stat(alg)->err_cnt);
-
-	return err;
-}
+int crypto_ahash_init(struct ahash_request *req);
 
 /**
  * crypto_ahash_update() - add data to message digest for processing
@@ -592,16 +543,7 @@ static inline int crypto_hash_errstat(struct hash_alg_common *alg, int err)
  *
  * Return: see crypto_ahash_final()
  */
-static inline int crypto_ahash_update(struct ahash_request *req)
-{
-	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
-	struct hash_alg_common *alg = crypto_hash_alg_common(tfm);
-
-	if (IS_ENABLED(CONFIG_CRYPTO_STATS))
-		atomic64_add(req->nbytes, &hash_get_stat(alg)->hash_tlen);
-
-	return crypto_hash_errstat(alg, tfm->update(req));
-}
+int crypto_ahash_update(struct ahash_request *req);
 
 /**
  * DOC: Asynchronous Hash Request Handle