Need some clarification about CRYPTO_AHASH_ALG_BLOCK_ONLY

[Paul Louvel <paul.louvel@bootlin.com>]

Hello,

I have stumbled across a flag defined in include/crypto/internal/hash.h : 
CRYPTO_AHASH_ALG_BLOCK_ONLY.
To get more information about what exact behavior this flag do, I read the 
crypto_ahash_update function.
 From the looks of it, it seems that the API will call the tfm update if there 
is enough bytes (and by enough I mean at least a block size), from the internal 
buffer and the incoming ahash_request.
In this case, I find the BLOCK_ONLY naming a bit of a misnomer, since it only 
guarantee you than req->nbytes will be at least a block size.
I initially though that the API would only give a request that are a multiple of 
the block size.

This flag, among others, are relatively recent.
I think adding documentation about these flags would be a great idea.

Regards,
Paul.

-- 
Paul Louvel, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com