When using realtime signals, we'll enqueue one signal for every event. This is unfortunate, because (for example) keyboard presses are three events: key, msc scancode, and syn. They'll be enqueued fast enough in kernel space that all three events will be ready to read by the time userspace runs, so the first invocation of the signal handler will read all three events, but then the second two invocations still have to run to do no work. Instead, only send the SIGIO notification on syn events. This is a slight abuse of SIGIO semantics, in principle it ought to fire as soon as any events are readable. But it matches evdev semantics, which is more important since SIGIO is rather vaguely defined to begin with. Signed-off-by: Adam Jackson <ajax@xxxxxxxxxx> --- drivers/input/evdev.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index dee6706..258c639 100644 --- a/drivers/input/evdev.c +++ b/drivers/input/evdev.c @@ -59,7 +59,8 @@ static void evdev_pass_event(struct evdev_client *client, client->head &= EVDEV_BUFFER_SIZE - 1; spin_unlock(&client->buffer_lock); - kill_fasync(&client->fasync, SIGIO, POLL_IN); + if (event->type == EV_SYN) + kill_fasync(&client->fasync, SIGIO, POLL_IN); } /* -- 1.6.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
