From: Greg KH on
2.6.32-stable review patch. If anyone has any objections, please let us know.


From: Bernd Porr <berndporr(a)>

commit d4c3a56587af3edbe5f618b20e800e9f9fde13cb upstream.

Jan-Matthias Braun spotted a bug which locks up the driver when the
comedi ring buffer runs empty and provided a patch. The driver would
still send the data to comedi but the reader won't wake up any more.
What's required is setting the flag COMEDI_CB_BLOCK after new data has
arrived which wakes up the reader and therefore the read() command.

Signed-off-by: Bernd Porr <berndporr(a)>
Signed-off-by: Leann Ogasawara <leann.ogasawara(a)>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)>

drivers/staging/comedi/drivers/usbdux.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/staging/comedi/drivers/usbdux.c
+++ b/drivers/staging/comedi/drivers/usbdux.c
@@ -1,4 +1,4 @@
-#define DRIVER_VERSION "v2.3"
+#define DRIVER_VERSION "v2.4"
#define DRIVER_AUTHOR "Bernd Porr, BerndPorr(a)"
#define DRIVER_DESC "Stirling/ITL USB-DUX -- Bernd.Porr(a)"
@@ -81,6 +81,8 @@ sampling rate. If you sample two channel
* 2.1: changed PWM API
* 2.2: added firmware kernel request to fix an udev problem
* 2.3: corrected a bug in bulk timeouts which were far too short
+ * 2.4: fixed a bug which causes the driver to hang when it ran out of data.
+ * Thanks to Jan-Matthias Braun and Ian to spot the bug and fix it.

@@ -532,6 +534,7 @@ static void usbduxsub_ai_IsocIrq(struct
/* tell comedi that data is there */
+ s->async->events |= COMEDI_CB_BLOCK | COMEDI_CB_EOS;
comedi_event(this_usbduxsub->comedidev, s);

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