Re: 2.2.20pre2aa1

[Andrea Arcangeli <andrea@suse.de>]

On Tue, May 15, 2001 at 08:33:05PM -0700, dean gaudet wrote:
> On Tue, 15 May 2001, Andrea Arcangeli wrote:
> 
> > o	fixed race in wake-one LIFO in accept(2). Apache must be compiled with
> > 	-DSINGLE_LISTEN_UNSERIALIZED_ACCEPT to take advantage of that.
> >
> > 00_wake-one-4
> >
> > 	Backport 2.4 waitqueues and in turn fixes an hanging condition in accept(2).
> >
> > 	(me)
> 
> apache since 1.3.15 has defined SINGLE_LISTEN_UNSERIALIZED_ACCEPT ...

That's definitely a good thing.

> 'cause that's what you guys asked me to do :)  does this mean there are
> known hangs on linux 2.2.x without your fix?

I never heard of anybody reproducing that but accpet() in 2.2
can _definitely_ miss events without the above 00_wake-one-4 patch
because it wrongly considers a progress wakeing up two times the same
exclusive task.

Furthmore the exclusive wakeup logic with the exclusive information
per-task and not per wait_queue_t will screwup if the tasks registers
itself like a wakeall after it was just registered as wakeone somewhere
else (however this second thing is more a theorical issue that shouldn't
trigger in 2.2).

Andrea