On Tue, 2014-04-08 at 15:17 +0200, Johan Hovold wrote: > [ +CC: Alan ] > > On Tue, Apr 08, 2014 at 12:33:31PM +0200, Oliver Neukum wrote: > > On Tue, 2014-04-08 at 09:33 +0200, Johan Hovold wrote: > > > On Tue, Apr 08, 2014 at 11:05:20AM +0800, Xiao Jin wrote: > > > > > > (2) acm tty port ASYNCB_INITIALIZED flag will be cleared when > > > > close. If acm resume callback run after ASYNCB_INITIALIZED flag > > > > cleared, there will have no chance for delayed write to start. > > > > That lead to acm_wb.use can't be cleared. If user space open > > > > acm tty again and try to setd, tty will be blocked in > > > > tty_wait_until_sent for ever. > > > > > > > > This patch have two modification. > > > > (1) use list_head to save the write acm_wb during acm suspend. > > > > It can ensure no acm write abandoned. > > > > (2) enable flush buffer callback when acm tty close. acm delayed > > > > wb will start before acm port shutdown callback, it make sure > > > > the delayed acm_wb.use to be cleared. The patch also clear > > > > acm_wb.use and acm.transmitting when port shutdown. > > > > > > This is not the right way to do this. See below. > > > > If I see this correctly, then ASYNCB_INITIALIZED is cleared in > > tty_port_close() we is called from acm_tty_close(). Thus it should > > be enough to make sure that the device is resumed at the beginning > > of acm_tty_close() and acm_resume() will do the job automatically. > > What do you think? > > But the device should already be about to be resumed, right? If the port Yes. > is closed fast enough that resume hasn't had time to run before > shutdown is called I think the right thing to do is simply to discard > the delayed bytes (in shutdown). I think if we said we have transmitted then we should do so. Regards Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
