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 <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
This commit is contained in:
Eric Biggers 2019-04-14 17:37:09 -07:00 • committed by Herbert Xu
commit 877b5691f2
66 changed files with 8 additions and 113 deletions

View file

@ -5443,7 +5443,6 @@ static int drbd_do_auth(struct drbd_connection *connection)
rcu_read_unlock();
desc->tfm = connection->cram_hmac_tfm;
desc->flags = 0;
rv = crypto_shash_setkey(connection->cram_hmac_tfm, (u8 *)secret, key_len);
if (rv) {

View file

@ -304,7 +304,6 @@ void drbd_csum_ee(struct crypto_shash *tfm, struct drbd_peer_request *peer_req,
void *src;
desc->tfm = tfm;
desc->flags = 0;
crypto_shash_init(desc);
@ -332,7 +331,6 @@ void drbd_csum_bio(struct crypto_shash *tfm, struct bio *bio, void *digest)
struct bvec_iter iter;
desc->tfm = tfm;
desc->flags = 0;
crypto_shash_init(desc);