On Sun, Feb 03, 2008 at 02:05:16PM +1100, Herbert Xu wrote:
> On Sun, Feb 03, 2008 at 12:37:19AM +0000, Al Viro wrote:
> >
> > This is still very odd... Where do you initialize ->seq.input? What
>
> In xfrm_input.
>
> > guarantees that async call of xfrm_input() will be always preceded by
> > at least one non-async one?
>
> OK I admit it isn't pretty. But the encap_type argument is reused to
> indicate async resumption. That is, if we enter with encap_type < 0,
> it means that we're resuming a previous operation and seq.input has
> therefore been set by the previous xfrm_input call.
*Ouch*
So what you are saying is
* callers of xfrm_input_resume() are in callbacks that couldn't
have been set other than from esp_input()/esp6_input()
* these two could have only been called via ->type->input()
* ->type->input() is called from xfrm_input(), immediately after
having set ->seq.input, *or* from xfrm6_input_addr(). The former is safe.
* xfrm6_input_addr() calls ->type->input() of object it gets from
xfrm_state_lookup_byaddr(). The protocol number passed to the latter comes
from xfrm6_input_addr() argument.
* the protocol numbers given to xfrm6_input_addr() by its callers
are IPPROTO_DSTOPTS and IPPROTO_ROUTING resp; ->input() instances in their
xfrm_type do *not* set callbacks that could lead to xfrm_input_resume(),
so we are safe.
IMO that at least deserves a comment near xfrm_input()...
doe
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