> > What stops a parallel open or close changing ASYNC_INITIALIZED after you > > test and before you lock ? > > Yeah, I should do the whole thing under the mutex. Can you use test_bit() as well. I'm trying to gradually push all the code that way so people habitually use set_bit() and we don't get any (more) races where some compile situations and architectures otherwise create load to register register ored with constant write back > Not related to this particular issue, but the fact that close() can powerdown > the hardware is quite bad. Today it is always possible to use open,close > sequence on /dev/ttyXXXX, and polling would break if close() deinitializes the > hardware (e.g. via uart_change_pm()). One of the long term goals of tty_port has always ben to have an object with the lifetime of the physical port so this kind of thing can be fixed. > In console= case, serial core handles the issue via uart_console(), checking if > the port is used for console, preventing it to power down the hardware. We can > do the same, or make tty_find_polling_driver() refcount individual ports/lines. > But the issue is orthogonal to this particular patch, although needs to be > fixed some day. Agreed - however you'll need a separate refcount than the main tty one for this, because we still need to do a hangup() on the final "tty" close even if the hardware is 'pinned' for a debugger. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
