Re: [PATCH] debug: Deprecate BUG_ON() use in new code, introduce CRASH_ON()

[Alexander Holler]

Am 08.06.2015 um 11:11 schrieb Ingo Molnar:
> * Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>
> > Firstly, the changelog of the patch that Greg rejected told nothing about all
> > that thinking, so at minimum it's a deficient changelog.
> >
> > Secondly and more importantly, instead of doing a BUG_ON() you could have done:
> >
> > 	if (WARN_ON_ONCE(port->itty))
> > 		return;
> >
> > This would probably have prevented the tty related memory corruption just as
> > much, at the cost of a (small and infrequent) memory leak.
> >
> > I.e. instead of crashing the machine, you need to try to find the least
> > destructive approach if a bug is detected.
>
> Also note that BUG_ON() will make data corruption _worse_ statistically. Why?
> Because most data corruptions are unlikely to be perfectly detected by a BUG_ON(),
> and the BUG_ON() delays the finding of the underlying bug, so the bug will hit
> more people before it's fixed for good.
>
> So even in the cases where you could argue that the system needs to stop, because
> we have evidence of data corruption, it's statistically the better approach to
> continue and get kernel log info back to developers.

Risking more, maybe even worse problems like corrupting file systems or 
similiar in order to have a slightly chance of save log info?

Sorry, that isn't something I would propose.

Anyway, CRASH_ON didn't exist, so I only had the choice between BUG_ON 
and WARN_ON, and for the latter you need a proper exit path which isn't 
always easy to find. So I appreciate CRASH_ON, thanks.

Alexander Holler
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