On Thursday 17 March 2011, Waldemar.Rymarkiewicz@xxxxxxxxx wrote: > >This is not very different from opening the file descriptor in > >multiple processes, which you prevent using your logic. > > but in the case when two independent applications try to open > my device I can't let the second to access. They obviously won't > synch the access. My point was that you don't need to worry. > >You can of course argue that you try your best to prevent the > >race. Traditionally, e.g. on serial ports and the like, we > >don't do this but instead rely on user space synchronizing the > >access. What you have to make sure of course is that multiple > >threads calling read on the same file can never bring the > >kernel driver into an invalid state. > > I assume, if an application shares the file pointer deliberately > it have to sync the access. In other cases, the driver needs to > secure it. As I said, it's not important if you do it and it certainly doesn't cause harm to prevent multiple open. It's just that generally we don't care too much about this problem. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
