Re: [PATCH v8] kernel, add panic_on_warn

[David Rientjes]

On Thu, 6 Nov 2014, Vivek Goyal wrote:

> On Thu, Nov 06, 2014 at 01:57:36PM -0800, David Rientjes wrote:
> 
> [..]
> > You see that doing
> > 
> > 	if (panic_on_warn) {
> > 		panic_on_warn = 0;
> > 		panic(...);
> > 	}
> > 
> > is racy, I hope.  If two threads WARN() at the same time, then there's 
> > nothing preventing a double panic() because WARN() itself is not 
> > serialized against anything.  So both the current comment and your 
> > suggested revision comment are bogus.
> 
> panic() is serialized on panic_lock. So I guess it is fine to hit WARN()
> on multiple cpus. Do you see an issue there?
> 

No issue at all, what's completely mysterious is the panic_on_warn = 0 and 
the completely bogus comment that says "prevent further WARN()s from 
panicking the system" when that's racy.  There's no need to clear 
panic_on_warn at all.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/