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

@ -332,7 +332,6 @@ static int crypt_iv_essiv_init(struct crypt_config *cc)
int err;
desc->tfm = essiv->hash_tfm;
desc->flags = 0;
err = crypto_shash_digest(desc, cc->key, cc->key_size, essiv->salt);
shash_desc_zero(desc);
@ -606,7 +605,6 @@ static int crypt_iv_lmk_one(struct crypt_config *cc, u8 *iv,
int i, r;
desc->tfm = lmk->hash_tfm;
desc->flags = 0;
r = crypto_shash_init(desc);
if (r)
@ -768,7 +766,6 @@ static int crypt_iv_tcw_whitening(struct crypt_config *cc,
/* calculate crc32 for every 32bit part and xor it */
desc->tfm = tcw->crc32_tfm;
desc->flags = 0;
for (i = 0; i < 4; i++) {
r = crypto_shash_init(desc);
if (r)

View file

@ -532,7 +532,6 @@ static void section_mac(struct dm_integrity_c *ic, unsigned section, __u8 result
unsigned j, size;
desc->tfm = ic->journal_mac;
desc->flags = 0;
r = crypto_shash_init(desc);
if (unlikely(r)) {
@ -1278,7 +1277,6 @@ static void integrity_sector_checksum(struct dm_integrity_c *ic, sector_t sector
unsigned digest_size;
req->tfm = ic->internal_hash;
req->flags = 0;
r = crypto_shash_init(req);
if (unlikely(r < 0)) {