[PATCH libinput] evdev: Log evdev event queue overflows

[Peter Hutterer]

On Tue, Oct 28, 2014 at 02:18:25PM -0500, Derek Foreman wrote:
> On 28/10/14 03:20 AM, Ran Benita wrote:
> > On Mon, Oct 27, 2014 at 09:26:39AM -0500, Derek Foreman wrote:
> >> Log a message when the kernel event queue overflows and events are dropped.
> >> After 10 messages logging stops to avoid flooding the logs if the condition
> >> is persistent.
> >> ---
> >>  src/evdev.c | 10 ++++++++++
> >>  1 file changed, 10 insertions(+)
> >>
> >> diff --git a/src/evdev.c b/src/evdev.c
> >> index 1b4ce10..c786537 100644
> >> --- a/src/evdev.c
> >> +++ b/src/evdev.c
> >> @@ -912,6 +912,7 @@ evdev_sync_device(struct evdev_device *device)
> >>  static void
> >>  evdev_device_dispatch(void *data)
> >>  {
> >> +	static int overflows = 0;
> > 
> > Does libinput allow static variables? Usually when there's a library
> > context, it should be possible to use the library from multiple threads,
> > if they use different contexts.
> > 
> > So maybe this counter should be inside `device` instead of static?
> 
> I'm not sure libinput is completely thread safe, but that's an easy
> change to make.
> 
> I'd like to put it in struct libinput to preserve the current behaviour
> - but that puts an evdev specific wart in an otherwise generic structure.
> 
> Any objections?

just put it into struct evdev_device, that's where it belongs best. means
you get the counter per device, but that's not a big deal IMO.

Cheers,
   Peter


> >>  	struct evdev_device *device = data;
> >>  	struct libinput *libinput = device->base.seat->libinput;
> >>  	struct input_event ev;
> >> @@ -924,6 +925,15 @@ evdev_device_dispatch(void *data)
> >>  		rc = libevdev_next_event(device->evdev,
> >>  					 LIBEVDEV_READ_FLAG_NORMAL, &ev);
> >>  		if (rc == LIBEVDEV_READ_STATUS_SYNC) {
> >> +			if (overflows < 10) {
> >> +				overflows++;
> >> +				log_info(libinput, "Kernel evdev event queue "
> >> +					 "overflow for %s\n", device->devname);
> >> +				if (overflows == 10)
> >> +					log_info(libinput, "No longer logging "
> >> +						 "evdev event queue overflows\n");
> >> +			}
> >> +
> >>  			/* send one more sync event so we handle all
> >>  			   currently pending events before we sync up
> >>  			   to the current state */
> >> -- 
> >> 2.1.1
> >>
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>