[PATCH 0/3] Make timers even more resistant to signals

[Daniel Kurtz]

On Wed, Oct 3, 2012 at 11:25 AM, Peter Hutterer
<peter.hutterer at who-t.net> wrote:
>
> On Fri, Sep 28, 2012 at 01:25:50AM -0700, Keith Packard wrote:
> > Peter Hutterer <peter.hutterer at who-t.net> writes:
> >
> > > Thanks, merged this into my tree. This should fix the remaining issues we're
> > > seeing with synaptics.
> >
> > Did you see my comments about this patch? I'm really not excited about
> > adding 12 more syscalls per WaitForSomething invocation. Seems like
> > there are two options to fix this 'correctly':
> >
> >  1) Have the synaptics driver modify the timer interval from either a
> >     wakeup or block handler as appropriate.
>
> A quick git grep shows that timers are used in keybard, mouse, joystick,
> synaptics, and wacom, all of those are in the signal path. We could in
> theory fix up the lot, but it will take time.
>
> >  2) Provide a signal-safe timer value setting function in DIX. This
> >     would set a global flag indicating that 'something' changed in the
> >     timers. WaitForSomething could use this flag to check whether the
> >     timers need fixing before computing the timeout value for select.
>
> > At the very least, the server should only be blocking SIGIO and not all
> > signals; that's half the syscalls...
>
> Both of these solutions seems to be more straightforward. Daniel?


Blocking only SIGIO is very straightforward.
The only reason I didn't do that is that the earlier patch used
OsBlockSignals().

Peter: Any reason you did that instead of xf86BlockSIGIO()?

Cheers,
Daniel

>
>
> Cheers,
>    Peter
>