On Sun, Dec 4, 2016 at 7:52 PM, Al Viro <v...@zeniv.linux.org.uk> wrote:
> 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?
I suppose this question is for Colin. ;)
