On Fri, Jan 06, 2012 at 07:55:44PM +0100, Henrik Rydberg wrote:

quoted

2 different processes should be fine; the problem would be if 2 threads
of the same process share the same file descriptor. So far the rest of
evdev copes just fine with multiple threads using the same fd (all
operations are atomic in this regard), setting ABS_MT_SLOT before
fetching the state break this property.

Are we talking about the need for a per-client mutex, or something
more subtle, like introducing indirect coupling between threads
through per-client states? The former ought to be easily remedied.

Ok, maybe not to so easy after all, which probably answers my own
question. Looks like a EVIOCGMTSLOT, taking both slot and event code
as argument, would be the cleaner route to take. Another ioctl, how do we
feel about that?

Henrik