On 24 января 2009 12:32:45 Herbert Xu wrote: > Andrey Borzenkov <arvidjaar@xxxxxxx> wrote: > > On 24 января 2009 01:31:50 Herbert Xu wrote: > >> 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. > > > > Could you point to example of such primitive in code under crypto? > > Grep for kmap under crypto. > I checked and - all usage is kmap_atomic; which implies it should be technically safe (not advisable) to use in interrupt context as well - as far as I understand, if it could be kmap() that could sleep, it is unsafe to use in tasklet anyway? Please bear with me. The problem with kernel is lack of any comprehensive documentation; so almost the only way to learn is by example - get code that is known to work and has at least /some/ documentation; and assume that what it does is correct. In this case incomplete or misleading documentation leads to adopting incorrect usage lately ... in this case I do not argue about code under crypto; but rather try to learn how and when I can safely use this code in my driver. So I still miss difference between interrupt context and bottom half (i.e. tasklet) that is made in documentation. Sorry :)
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