2009/9/3 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > On Thu, 3 Sep 2009, Ming Lei wrote: > >> > - ++port->port.count; >> > + spin_lock_irq(&port->port.lock); >> > + if (!tty_hung_up_p(filp)) >> > + ++port->port.count; >> > + spin_unlock_irq(&port->port.lock); >> >> The lock is still needed in usb_console_setup() to protect port->port.count, >> isn't it? > > Is it? I don't know. The lock is needed to protect against concurrent > open, close, and hangup events. Does usb_console_setup() run before > any of those things can occur? IMHO, /dev/ttyUSB0 may be created before usb_console_setup(), so it is possible that open() and usb_console_setup() are concurrent. > > One thing that _is_ clear is that usb_console_setup() needs to release > serial->disc_mutex. I didn't notice that it called > usb_serial_get_by_index(). > > Alan Stern > > -- Lei Ming -- 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
