Re: [PATCH v2 1/1] mux: mux-core: Add NULL check for dev->of_node

From: Kuppuswamy, Sathyanarayanan
Date: Sat Jul 08 2017 - 19:12:48 EST

Hi Peter,

On 7/8/2017 2:00 PM, Peter Rosin wrote:
On 2017-07-07 23:46, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote:
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>

If dev->of_node is NULL, then calling mux_control_get()
function can lead to NULL pointer exception. So adding
a NULL check for dev->of_node.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
Do you have a driver that might call mux_control_get and not have any
For non-device tree drivers, this case is valid. I hit this issue when I was working on Intel USB MUX driver.
If not, I don't see the point of this check.
Since this is an API for other consumers, I think its better to have some sanity checks.

If a non device tree driver call this API , I think its better to fail with some error no instead of creating null pointer exception.


drivers/mux/mux-core.c | 3 +++
1 file changed, 3 insertions(+)

Changes since v1:
* Removed dummy new line.

diff --git a/drivers/mux/mux-core.c b/drivers/mux/mux-core.c
index 90b8995..924c983 100644
--- a/drivers/mux/mux-core.c
+++ b/drivers/mux/mux-core.c
@@ -438,6 +438,9 @@ struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
int index = 0;
int ret;
+ if (!np)
+ return ERR_PTR(-ENODEV);
if (mux_name) {
index = of_property_match_string(np, "mux-control-names",