On Sun, Dec 04, 2016 at 09:42:14PM -0500, David Miller wrote:
> > I've run into that converting AF_UNIX to generic_file_splice_read();
> > I can kludge around that ("freezable unless ->msg_iter is ITER_PIPE"), but
> > that only delays trouble.
> >
> > Note that the only other user of freezable_schedule_timeout() is
> > a very different story - it's a kernel thread, which *does* have a
> > guaranteed
> > locking environment. Making such assumptions in unix_stream_recvmsg(),
> > OTOH, is insane...
>
> We have to otherwise Android phones drain their batteries in 10
> minutes.
>
> I'm not going to revert this and be responsible for that.
>
> So you have to find a way to make the freezable calls legitimate.
Oh, well... As I said, I can kludge around that - call from
generic_file_splice_read() can be distinguished by looking at the
->msg_iter->type; it still means unpleasantness for kernel_recvmsg()
users - in effect, it can only be called with locks held if you know that
the socket is not an AF_UNIX one.
BTW, how do they deal with plain pipes?
