On 01/06/2012 10:18 AM, Dmitry Torokhov wrote: > Hi Benjamin, > > On Fri, Jan 06, 2012 at 07:00:22PM +0100, Benjamin Tissoires wrote: >> Hi guys, >> I read somewhere in the code of Android a comment in which they >> complain about not being able to retrieve the slots states. So they >> assume they are all at 0. >> So this mechanism is good to have. >> However, back in January 2011, Dmitry raised the problem that this >> code was not thread safe.What happens if 2 applications ask for >> different slots values (let say X.org and utouch-frame)? > > 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. How is this any different than two threads trying to set a different property, like the fuzz factor of an axis? This seems like something that should be guarded by a lock in userspace, essentially. -- Chase -- 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
