[PATCH 5/6] null_blk: check for valid max_sectors value

[Chaitanya Kulkarni <kch@nvidia.com>]

Right now we don't check for valid module parameter value for
max_sectors, that allows user to set negative values.

Add a callback to error out when max_sectors value is set < 1 before
module is loaded.

Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
---
 drivers/block/null_blk/main.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 7cfc1eaa5e3c..1b9fa5af02d5 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -195,7 +195,18 @@ device_param_cb(bs, &null_bs_param_ops, &g_bs, 0444);
 MODULE_PARM_DESC(bs, "Block size (in bytes)");
 
 static int g_max_sectors;
-module_param_named(max_sectors, g_max_sectors, int, 0444);
+
+static int null_set_max_sects(const char *s, const struct kernel_param *p)
+{
+	return null_param_store_val(s, &g_max_sectors, 1, INT_MAX);
+}
+
+static const struct kernel_param_ops null_max_sects_param_ops = {
+	.set	= null_set_max_sects,
+	.get	= param_get_int,
+};
+
+device_param_cb(max_sectors, &null_max_sects_param_ops, &g_max_sectors, 0444);
 MODULE_PARM_DESC(max_sectors, "Maximum size of a command (in 512B sectors)");
 
 static unsigned int nr_devices = 1;
-- 
2.29.0