Re: [PATCH] NetCP: Deletion of unnecessary checks before two function calls

Dan Carpenter
2015-02-05T12:02:03Z

Hi Wingman,

There are some bugs in this error handling.

On Tue, Feb 03, 2015 at 08:22:23PM +0100, SF Markus Elfring wrote:
> diff --git a/drivers/net/ethernet/ti/netcp_ethss.c b/drivers/net/ethernet/ti/netcp_ethss.c
> index fa1041a..cbd6dde 100644
> --- a/drivers/net/ethernet/ti/netcp_ethss.c
> +++ b/drivers/net/ethernet/ti/netcp_ethss.c
> @@ -2010,12 +2010,10 @@ static int gbe_probe(struct netcp_device *netcp_device, struct device *dev,
> quit:
> if (gbe_dev->hw_stats)
> devm_kfree(dev, gbe_dev->hw_stats);
> - if (gbe_dev->ale)
> - cpsw_ale_destroy(gbe_dev->ale);
> + cpsw_ale_destroy(gbe_dev->ale);
> if (gbe_dev->ss_regs)
> devm_iounmap(dev, gbe_dev->ss_regs);
> - if (interfaces)
> - of_node_put(interfaces);
> + of_node_put(interfaces);
^^^^^^^^^^
"interfaces" is sometimes unintialized in this code. I don't know why
GCC doesn't catch this... :(

This is a "one rrr bug", which is caused because you just have one error
label "quit" which handles all the error handling. Please read my
Google+ comment on error handling.

https://plus.google.com/106378716002406849458/posts/dnanfhQ4mHQ

> devm_kfree(dev, gbe_dev);
^^^^^^^^^^^^^^^^^^^^^^^^
This is not the right way to use the devm_ interface. These things are
freed automatically on error or when we are done with them. This driver
is double freeing pretty much everything. Grep for devm_kfree() and
fix everything.

I don't know why kbuild didn't catch this...

regards
dan carpenter