If the usermode app does an ioctl over this serial device by using TIOCMIWAIT, then the code will wait by setting the current task state to TASK_INTERRUPTIBLE and then calling schedule(). This will be woken up by the qt2_process_modem_status on URB completion when the port_extra->shadowMSR is set to the new modem status. However, this could result in a lost wakeup scenario due to a race in the logic in the qt2_ioctl(TIOCMIWAIT) loop and the URB completion for new modem status in qt2_process_modem_status. Due to this, the usermode app's task will continue to sleep despite a change in the modem status. Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
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quatech_usb2.c |