suspected null-pointer-reference problem for to_swnode

[YE Chengfeng]

Hi, 

https://github.com/torvalds/linux/blob/master/drivers/base/swnode.c#L405

We notice that the return pointer of to_swnode is null check in some case, while in some case is not. For example, at line 416, the return pointer is null-check, but in line 405 is not. We want to know whether it would be a potential null pointer dereference problem, in the case that null-check is missing.

This problem is detected by our experimental static analysis tool, we are not familiar with the source code and it could just be a false positive. We send this email in case this is a real problem. Would you like to spare some time to have a look at it?

Thanks so much,
Chengfeng