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Commit d4c3a565 authored by Bernd Porr's avatar Bernd Porr Committed by Greg Kroah-Hartman
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Staging: comedi: usbdux.c: fix locking up of the driver when the comedi ringbuffer runs empty 



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: default avatarBernd Porr <berndporr@f2s.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 29d249ed

drivers/staging/comedi/drivers/usbdux.c

+4 −1
Original line number Diff line number Diff line 
#define DRIVER_VERSION "v2.3"

#define DRIVER_VERSION "v2.4"

#define DRIVER_AUTHOR "Bernd Porr, BerndPorr@f2s.com"

#define DRIVER_DESC "Stirling/ITL USB-DUX -- Bernd.Porr@f2s.com"

/*
@@ -81,6 +81,8 @@ sampling rate. If you sample two channels you get 4kHz and so on. 
 * 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 urb *urb) 
		}

	}

	/* tell comedi that data is there */

	s->async->events |= COMEDI_CB_BLOCK | COMEDI_CB_EOS;

	comedi_event(this_usbduxsub->comedidev, s);

}