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

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Message-Id: <20171024.174842.272234711073180328.davem@davemloft.net>
Date:   Tue, 24 Oct 2017 17:48:42 +0900 (KST)
From:   David Miller <davem@...emloft.net>
To:     herbert@...dor.apana.org.au
Cc:     garsilva@...eddedor.com, steffen.klassert@...unet.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: xfrm_user: use BUG_ON instead of if condition
 followed by BUG

From: Herbert Xu <herbert@...dor.apana.org.au>
Date: Tue, 24 Oct 2017 11:53:20 +0800

> No your patch makes it worse.  The original construct makes it
> clear that the conditional is real code and not just some debugging
> aid.
> 
> With your patch, real code is now inside BUG_ON.

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.