Re: Clarification of allowed context for crypto routines

[Herbert Xu]

Andrey Borzenkov <arvidjaar@xxxxxxx> wrote:
>
> As I can understand, user context requirement is due to potential for 
> setkey to sleep (although it appears, that currently the only module 
> that can sleep is shash which is calling kmalloc with GFP_KERNEL). Is it 
> correct?

Yep.

> But where is the difference between hard and softirq contexts? I fail to 
> see any technical reason for this requirement.

The reasons are two-fold:

1) Crypto operations are so slow in general that if you did them
in hard IRQ context it would just be wrong;

2) The highmem primitives we use are currently softirq only.  We
could make them work for hardirq as well, but because of 1) we
didn't.

Cheers,
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