null_blk: boundary check queue_mode and irqmode

When either queue_mode or irq_mode parameter is set outside its
boundaries, the driver will not complete requests. This stalls driver
initialization when partitions are probed. Fix by setting out of bound
values to the parameters default.
Signed-off-by: Matias Bjørling <m@bjorling.me>

Updated by me to have the parse+check in just one function.
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/null_blk.c

@@ -78,7 +78,33 @@ module_param(home_node, int, S_IRUGO);
 MODULE_PARM_DESC(home_node, "Home node for the device");
 
 static int queue_mode = NULL_Q_MQ;
-module_param(queue_mode, int, S_IRUGO);
+
+static int null_param_store_val(const char *str, int *val, int min, int max)
+{
+	int ret, new_val;
+
+	ret = kstrtoint(str, 10, &new_val);
+	if (ret)
+		return -EINVAL;
+
+	if (new_val < min || new_val > max)
+		return -EINVAL;
+
+	*val = new_val;
+	return 0;
+}
+
+static int null_set_queue_mode(const char *str, const struct kernel_param *kp)
+{
+	return null_param_store_val(str, &queue_mode, NULL_Q_BIO, NULL_Q_MQ);
+}
+
+static struct kernel_param_ops null_queue_mode_param_ops = {
+	.set	= null_set_queue_mode,
+	.get	= param_get_int,
+};
+
+device_param_cb(queue_mode, &null_queue_mode_param_ops, &queue_mode, S_IRUGO);
 MODULE_PARM_DESC(queue_mode, "Block interface to use (0=bio,1=rq,2=multiqueue)");
 
 static int gb = 250;
@@ -94,7 +120,19 @@ module_param(nr_devices, int, S_IRUGO);
 MODULE_PARM_DESC(nr_devices, "Number of devices to register");
 
 static int irqmode = NULL_IRQ_SOFTIRQ;
-module_param(irqmode, int, S_IRUGO);
+
+static int null_set_irqmode(const char *str, const struct kernel_param *kp)
+{
+	return null_param_store_val(str, &irqmode, NULL_IRQ_NONE,
+					NULL_IRQ_TIMER);
+}
+
+static struct kernel_param_ops null_irqmode_param_ops = {
+	.set	= null_set_irqmode,
+	.get	= param_get_int,
+};
+
+device_param_cb(irqmode, &null_irqmode_param_ops, &irqmode, S_IRUGO);
 MODULE_PARM_DESC(irqmode, "IRQ completion handler. 0-none, 1-softirq, 2-timer");
 
 static int completion_nsec = 10000;