lkml.org 
[lkml]   [2020]   [Mar]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.5 018/189] usb: gadget: serial: fix Tx stall after buffer overflow
    Date
    From: Sergey Organov <sorganov@gmail.com>

    [ Upstream commit e4bfded56cf39b8d02733c1e6ef546b97961e18a ]

    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 <sorganov@gmail.com>
    Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
    Signed-off-by: Felipe Balbi <balbi@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/usb/gadget/function/u_serial.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
    index f986e5c559748..8167d379e115b 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);
    --
    2.20.1


    \
     
     \ /
      Last update: 2020-03-10 14:27    [W:2.616 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site