git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From d4c3a56587af3edbe5f618b20e800e9f9fde13cb Mon Sep 17 00:00:00 2001
   2 From: Bernd Porr <berndporr@f2s.com>
   3 Date: Fri, 27 Nov 2009 12:00:53 +0000
   4 Subject: Staging: comedi: usbdux.c: fix locking up of the driver when the comedi ringbuffer runs empty
   5
   6 From: Bernd Porr <berndporr@f2s.com>
   7
   8 commit d4c3a56587af3edbe5f618b20e800e9f9fde13cb upstream.
   9
  10 Jan-Matthias Braun spotted a bug which locks up the driver when the
  11 comedi ring buffer runs empty and provided a patch. The driver would
  12 still send the data to comedi but the reader won't wake up any more.
  13 What's required is setting the flag COMEDI_CB_BLOCK after new data has
  14 arrived which wakes up the reader and therefore the read() command.
  15
  16 Signed-off-by: Bernd Porr <berndporr@f2s.com>
  17 Signed-off-by: Leann Ogasawara <leann.ogasawara@canonical.com>
  18 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  19
  20 ---
  21  drivers/staging/comedi/drivers/usbdux.c |    5 ++++-
  22  1 file changed, 4 insertions(+), 1 deletion(-)
  23
  24 --- a/drivers/staging/comedi/drivers/usbdux.c
  25 +++ b/drivers/staging/comedi/drivers/usbdux.c
  26 @@ -1,4 +1,4 @@
  27 -#define DRIVER_VERSION "v2.3"
  28 +#define DRIVER_VERSION "v2.4"
  29  #define DRIVER_AUTHOR "Bernd Porr, BerndPorr@f2s.com"
  30  #define DRIVER_DESC "Stirling/ITL USB-DUX -- Bernd.Porr@f2s.com"
  31  /*
  32 @@ -81,6 +81,8 @@ sampling rate. If you sample two channel
  33   * 2.1:  changed PWM API
  34   * 2.2:  added firmware kernel request to fix an udev problem
  35   * 2.3:  corrected a bug in bulk timeouts which were far too short
  36 + * 2.4:  fixed a bug which causes the driver to hang when it ran out of data.
  37 + *       Thanks to Jan-Matthias Braun and Ian to spot the bug and fix it.
  38   *
  39   */
  40
  41 @@ -532,6 +534,7 @@ static void usbduxsub_ai_IsocIrq(struct
  42                 }
  43         }
  44         /* tell comedi that data is there */
  45 +       s->async->events |= COMEDI_CB_BLOCK | COMEDI_CB_EOS;
  46         comedi_event(this_usbduxsub->comedidev, s);
  47  }
  48