Messages in this thread | | | Date | Fri, 16 Apr 2010 16:59:22 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH v2] [watchdog] combine nmi_watchdog and softlockup |
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On Fri, Apr 16, 2010 at 04:53:11PM +0200, Peter Zijlstra wrote: > On Fri, 2010-04-16 at 16:46 +0200, Frederic Weisbecker wrote: > > > > May be have an arch spin lock there to update your cpu mask safely. > > > > > > > > > > Hmm, this is NMI handler path so from what we protect this per-cpu data? > > > Do I miss something? /me confused > > > > > > The cpu mask is not per cpu here, this is a shared bitmap, so you > > can race against other cpus NMIs. > > > > That said, as I suggested, having a per cpu var that we set when we > > warned would be much better than a spinlock here. > > Every time you think NMI and spinlock think FAIL.
In fact I was first inspired by the x86 nmi watchdog handler that does this spinlock to protect cpumask, but realize just after my FAIL ;-)
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