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staging: comedi: rtd520: prevent "empty acquisition" async command 

This driver currently allows a cmd->stop_src == TRIG_COUNT with a cmd->stop_arg
of 0. The (*do_cmd) then sets up and starts the command without handling the "empty
acquisition". This results in the interrupt function trying to transfer 0 data
samples.

Validate that the cmd->stop_arg is >= 1 in the (*do_cmdtest) to prevent the
"empty acquisition".

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
H Hartley Sweeten 2014-09-09 16:16:00 -07:00 committed by Greg Kroah-Hartman
parent 1e2e39effd
commit 8c602c498c
1 changed files with 3 additions and 5 deletions
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8
drivers/staging/comedi/drivers/rtd520.c
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@ -874,12 +874,10 @@ static int rtd_ai_cmdtest(struct comedi_device *dev,
err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);
if (cmd->stop_src == TRIG_COUNT) {
/* TODO check for rounding error due to counter wrap */
} else {
/* TRIG_NONE */
if (cmd->stop_src == TRIG_COUNT)
err |= cfc_check_trigger_arg_min(&cmd->stop_arg, 1);
else /* TRIG_NONE */
err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);
}
if (err)
return 3;