--- a/drivers/cbus/retu.c
+++ b/drivers/cbus/retu.c
@@ -198,10 +198,12 @@ static irqreturn_t retu_irq_handler(int
u16 idr;
u16 imr;
+ mutex_lock(&retu->mutex);
idr = __retu_read_reg(retu, RETU_REG_IDR);
imr = __retu_read_reg(retu, RETU_REG_IMR);
- idr &= ~imr;
+ mutex_unlock(&retu->mutex);
+ idr &= ~imr;
if (!idr) {
dev_vdbg(retu->dev, "No IRQ, spurious?\n");
return IRQ_NONE;