From: Sergey Organov Date: Wed, 29 Jan 2020 11:21:46 +0000 (+0300) Subject: usb: gadget: serial: fix Tx stall after buffer overflow X-Git-Tag: v5.10.7~3187^2~2^2~1 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e4bfded56cf39b8d02733c1e6ef546b97961e18a;p=platform%2Fkernel%2Flinux-rpi.git usb: gadget: serial: fix Tx stall after buffer overflow Symptom: application opens /dev/ttyGS0 and starts sending (writing) to it while either USB cable is not connected, or nobody listens on the other side of the cable. If driver circular buffer overflows before connection is established, no data will be written to the USB layer until/unless /dev/ttyGS0 is closed and re-opened again by the application (the latter besides having no means of being notified about the event of establishing of the connection.) Fix: on open and/or connect, kick Tx to flush circular buffer data to USB layer. Signed-off-by: Sergey Organov Reviewed-by: Michał Mirosław Signed-off-by: Felipe Balbi --- diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index f986e5c..8167d37 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -561,8 +561,10 @@ static int gs_start_io(struct gs_port *port) port->n_read = 0; started = gs_start_rx(port); - /* unblock any pending writes into our circular buffer */ if (started) { + gs_start_tx(port); + /* Unblock any pending writes into our circular buffer, in case + * we didn't in gs_start_tx() */ tty_wakeup(port->port.tty); } else { gs_free_requests(ep, head, &port->read_allocated);