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Staging: comedi: usbdux.c: fix locking up of the driver when the comedi ringbuffer runs empty

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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@f2s.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Bernd Porr 2009-11-27 12:00:53 +00:00 committed by Greg Kroah-Hartman
parent 29d249ed80
commit d4c3a56587
1 changed files with 4 additions and 1 deletions
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5
drivers/staging/comedi/drivers/usbdux.c
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@ -1,4 +1,4 @@
#define DRIVER_VERSION "v2.3" #define DRIVER_VERSION "v2.4"
#define DRIVER_AUTHOR "Bernd Porr, BerndPorr@f2s.com" #define DRIVER_AUTHOR "Bernd Porr, BerndPorr@f2s.com"
#define DRIVER_DESC "Stirling/ITL USB-DUX -- Bernd.Porr@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 * 2.1: changed PWM API
* 2.2: added firmware kernel request to fix an udev problem * 2.2: added firmware kernel request to fix an udev problem
* 2.3: corrected a bug in bulk timeouts which were far too short * 2.3: 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 */ /* tell comedi that data is there */
s->async->events |= COMEDI_CB_BLOCK | COMEDI_CB_EOS;
comedi_event(this_usbduxsub->comedidev, s); comedi_event(this_usbduxsub->comedidev, s);
} }