Re: [PATCH] net: xfrm_user: use BUG_ON instead of if condition followed by BUG

[David Miller]

From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Date: Wed, 25 Oct 2017 12:05:41 +0800

> On Tue, Oct 24, 2017 at 05:48:42PM +0900, David Miller wrote:
>> 
>> This discussion has happened before.
>> 
>> But I'll explain the conclusion here for your benefit.
>> 
>> BUG_ON() is a statement and everything inside of it will
>> always execute.
>> 
>> BUG_ON() is always preferred because it allows arch
>> specific code to pass the conditional result properly
>> into inline asm and builtins for optimal code generation.
> 
> This is a good point.  However, while a little bit more verbose you
> can still achieve the same assembly-level result by something like
> 
> 	int err;
> 
> 	err = <insert real code here>;
> 	BUG_ON(err);
> 
> Having real code in BUG_ON may pose problems to people reading the
> code because some of us tend to ignore code in BUG_ON and similar
> macros such as BUILD_BUG_ON.

I agree that this makes the code easier to read and audit.