Messages in this thread | | | Date | Thu, 21 Feb 2013 19:21:59 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] nohz: Make tick_nohz_irq_exit() irq safe |
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On Thu, 21 Feb 2013, Linus Torvalds wrote:
> On Wed, Feb 20, 2013 at 1:00 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > > */ > > void irq_exit(void) > > { > > +#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED > > + unsigned long flags; > > + > > + local_irq_save(flags); > > +#else > > + BUG_ON(!irqs_disabled(); > > +#endif > > Guys, STOP DOING THIS! > > Adding BUG_ON()'s just makes things much much much worse. There is > *never* a reason to add a BUG_ON(). And doing it in an interrupt path > is totally unacceptable. BUG_ON() makes it almost impossible to debug > something, because you just killed the machine. So using BUG_ON() for > "please notice this" is stupid as hell, because the most common end > result is: "Oh, the machine just hung with no messages". > > Make it WARN_ON_ONCE() if you absolutely have to let people know, but > for something like this, why would you do even that?
This was a draft patch. I made it a WARN_ON_ONCE() already.
We really want to enforce that irq_exit() is called with interrupts disabled.
Thanks,
tglx
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