• Eric Biggers's avatar
    crypto: shash - remove shash_desc::flags · 877b5691
    Eric Biggers authored
    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: default avatarEric Biggers <ebiggers@google.com>
    Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
    877b5691
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