crypto: shash - remove shash_desc::flags

The flags field in 'struct shash_desc' never actually does anything.
The only ostensibly supported flag is CRYPTO_TFM_REQ_MAY_SLEEP.
However, no shash algorithm ever sleeps, making this flag a no-op.

With this being the case, inevitably some users who can't sleep wrongly
pass MAY_SLEEP.  These would all need to be fixed if any shash algorithm
actually started sleeping.  For example, the shash_ahash_*() functions,
which wrap a shash algorithm with the ahash API, pass through MAY_SLEEP
from the ahash API to the shash API.  However, the shash functions are
called under kmap_atomic(), so actually they're assumed to never sleep.

Even if it turns out that some users do need preemption points while
hashing large buffers, we could easily provide a helper function
crypto_shash_update_large() which divides the data into smaller chunks
and calls crypto_shash_update() and cond_resched() for each chunk.  It's
not necessary to have a flag in 'struct shash_desc', nor is it necessary
to make individual shash algorithms aware of this at all.

Therefore, remove shash_desc::flags, and document that the
crypto_shash_*() functions can be called from any context.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 0 insertions, 5 deletions

diff --git a/drivers/crypto/padlock-sha.c b/drivers/crypto/padlock-sha.c
index 21e5cae0a1e0..e641481a3cd9 100644
--- a/drivers/crypto/padlock-sha.c
+++ b/drivers/crypto/padlock-sha.c
@@ -39,7 +39,6 @@ static int padlock_sha_init(struct shash_desc *desc)
 	struct padlock_sha_ctx *ctx = crypto_shash_ctx(desc->tfm);
 
 	dctx->fallback.tfm = ctx->fallback;
-	dctx->fallback.flags = desc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 	return crypto_shash_init(&dctx->fallback);
 }
 
@@ -48,7 +47,6 @@ static int padlock_sha_update(struct shash_desc *desc,
 {
 	struct padlock_sha_desc *dctx = shash_desc_ctx(desc);
 
-	dctx->fallback.flags = desc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 	return crypto_shash_update(&dctx->fallback, data, length);
 }
 
@@ -65,7 +63,6 @@ static int padlock_sha_import(struct shash_desc *desc, const void *in)
 	struct padlock_sha_ctx *ctx = crypto_shash_ctx(desc->tfm);
 
 	dctx->fallback.tfm = ctx->fallback;
-	dctx->fallback.flags = desc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 	return crypto_shash_import(&dctx->fallback, in);
 }
 
@@ -91,7 +88,6 @@ static int padlock_sha1_finup(struct shash_desc *desc, const u8 *in,
 	unsigned int leftover;
 	int err;
 
-	dctx->fallback.flags = desc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 	err = crypto_shash_export(&dctx->fallback, &state);
 	if (err)
 		goto out;
@@ -153,7 +149,6 @@ static int padlock_sha256_finup(struct shash_desc *desc, const u8 *in,
 	unsigned int leftover;
 	int err;
 
-	dctx->fallback.flags = desc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 	err = crypto_shash_export(&dctx->fallback, &state);
 	if (err)
 		goto out;