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crypto: shash - remove shash_desc::flags

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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>
This commit is contained in:
Eric Biggers
2019-04-14 17:37:09 -07:00
committed by Herbert Xu
parent 75f2222832
commit 877b5691f2
66 changed files with 8 additions and 113 deletions
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6
fs/ubifs/auth.c
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@@ -33,7 +33,6 @@ int __ubifs_node_calc_hash(const struct ubifs_info *c, const void *node,
int err;
shash->tfm = c->hash_tfm;
shash->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
err = crypto_shash_digest(shash, node, le32_to_cpu(ch->len), hash);
if (err < 0)
@@ -56,7 +55,6 @@ static int ubifs_hash_calc_hmac(const struct ubifs_info *c, const u8 *hash,
int err;
shash->tfm = c->hmac_tfm;
shash->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
err = crypto_shash_digest(shash, hash, c->hash_len, hmac);
if (err < 0)
@@ -88,7 +86,6 @@ int ubifs_prepare_auth_node(struct ubifs_info *c, void *node,
return -ENOMEM;
hash_desc->tfm = c->hash_tfm;
hash_desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
ubifs_shash_copy_state(c, inhash, hash_desc);
err = crypto_shash_final(hash_desc, hash);
@@ -123,7 +120,6 @@ static struct shash_desc *ubifs_get_desc(const struct ubifs_info *c,
return ERR_PTR(-ENOMEM);
desc->tfm = tfm;
desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
err = crypto_shash_init(desc);
if (err) {
@@ -364,7 +360,6 @@ static int ubifs_node_calc_hmac(const struct ubifs_info *c, const void *node,
ubifs_assert(c, ofs_hmac + hmac_len < len);
shash->tfm = c->hmac_tfm;
shash->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
err = crypto_shash_init(shash);
if (err)
@@ -483,7 +478,6 @@ int ubifs_hmac_wkm(struct ubifs_info *c, u8 *hmac)
return 0;
shash->tfm = c->hmac_tfm;
shash->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
err = crypto_shash_init(shash);
if (err)