[PATCH 10/14] staging: comedi: amplc_pc236_common: Use 16-bit 0 for interrupt data

Ian Abbott abbotti at mev.co.uk
Tue Feb 23 14:30:51 UTC 2021


The Amplicon PC36AT/PCI236 common driver has an "interrupt" subdevice
that supports Comedi asynchronous commands, placing a value in the
Comedi buffer for each interrupt.  The subdevice uses Comedi's 16-bit
sample format but the interrupt handler is calling
`comedi_buf_write_samples()` with the address of a 32-bit integer
`&s->state`.  On bigendian machines, this will copy 2 bytes from the
wrong end of the 32-bit integer.  This isn't really a problem since
`s->state` will always be 0 for this subdevice, but clean it up by using
a 16-bit variable initialized to 0 to pass the value.

Signed-off-by: Ian Abbott <abbotti at mev.co.uk>
---
 drivers/staging/comedi/drivers/amplc_pc236_common.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/comedi/drivers/amplc_pc236_common.c b/drivers/staging/comedi/drivers/amplc_pc236_common.c
index 043752663188..981d281e87a1 100644
--- a/drivers/staging/comedi/drivers/amplc_pc236_common.c
+++ b/drivers/staging/comedi/drivers/amplc_pc236_common.c
@@ -126,7 +126,9 @@ static irqreturn_t pc236_interrupt(int irq, void *d)
 
 	handled = pc236_intr_check(dev);
 	if (dev->attached && handled) {
-		comedi_buf_write_samples(s, &s->state, 1);
+		unsigned short val = 0;
+
+		comedi_buf_write_samples(s, &val, 1);
 		comedi_handle_events(dev, s);
 	}
 	return IRQ_RETVAL(handled);
-- 
2.30.0



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