linux-kernel - Re: [RFC] asm-generic: default BUG

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Message-ID: <20151123165219.GD768@1wt.eu>
Date:	Mon, 23 Nov 2015 17:52:19 +0100
From:	Willy Tarreau <w@....eu>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	linux-arch@...r.kernel.org, josh@...htriplett.org,
	linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC] asm-generic: default BUG_ON(x) to "if(x) BUG()"

On Mon, Nov 23, 2015 at 04:37:50PM +0000, Russell King - ARM Linux wrote:
> On Mon, Nov 23, 2015 at 05:33:59PM +0100, Willy Tarreau wrote:
> > I think you could do better by simply calling panic("BUG!") instead as
> > BUG() does. It will avoid the printk() call and pushing the file/line
> > number onto the stack. It will also probably not inflate the rodata this
> > way.
> 
> Does that not depend on the architectures BUG() implementation?  If an
> architecture implements it as a signalling illegal instruction and a
> lookup table, changing it to be a panic() would probably be more code.

That's a very good point, I didn't think about it and yes I think you're
right then (eg: when CONFIG_DEBUG_BUGVERBOSE is not set, x86 and arm will
only emit a single instruction).

Best regards,
Willy

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