> > when != e = id achieves this behavior.
> 
> I can not agree to this view completely because of the meaning that is connected
> with these variable identifiers.
> 
> Both metavariables share the kind “expression”. So I can imagine
> that there is an intersection for the source code match possibility.
> But one was intentionally restricted to the kind “local idexpression” so far.
> 
> Which data element should not get reassigned here (before a corresponding
> null pointer check)?
> 

Thank you for your comments.
We did some experiments:
+id = of_find_device_by_node@p1(x)
+... when != e = id
...
Or:
...
+ ... when != id = e

The number of issuses found by these two methods is the same.
When != e = id achieves this behavior.

In addition, we feel that we should probably accept this patch first, use it to find more memory leaks, and solve the actual problems in the kernel code.
As for the patch itself, we can continue to pursue perfect in the process of using it to solve practical problems.

Regards,
Wen