[CRIU] [PATCH 1/4] signalfd: add ability to return siginfo in a raw format

[Oleg Nesterov]

On 12/25, Pavel Emelyanov wrote:
>
> On 12/25/2012 07:27 PM, Oleg Nesterov wrote:
> >
> > I guess that probably you actually need DUMP, not DEQUEUE. but the
> > latter is not trivial. However, perhaps we can do this assuming that
> > all other threads are sleeping and nobody can do dequeue_signal().
> > Say, we can play with ppos/llseek. If *ppos is not zero,
> > signalfd_dequeue() could dump the nth entry from list or return 0.
>
> This would be perfect, but isn't it better to preserve the pos
> semantics -- we do know size of entry we're about to copy, we can
> treat pos as offset in bytes, not in elements.

nr-of-records looks better (more flexible) than nr-of-bytes to me. And
perhaps we can also encode private-or-shared into ppos. But I will not
argue in any case.

Oleg.