Re: [GIT PULL] RCU changes for v3.3

[Eric Dumazet]

Le mardi 24 janvier 2012 Ã 08:53 -0800, Paul E. McKenney a Ãcrit :
> On Tue, Jan 24, 2012 at 05:25:12PM +0100, Eric Dumazet wrote:
> > Le jeudi 05 janvier 2012 Ã 14:54 +0100, Ingo Molnar a Ãcrit :
> > > Linus,
> > > 
> > > Please pull the latest core-rcu-for-linus git tree from:
> > > 
> > >    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-rcu-for-linus
> > > 
> > >  Thanks,
> > 
> > Hi guys
> > 
> > New lockdep warning here :
> 
> Hmmm...  Looks like tracing from within the inner idle loop.
> 
> Because RCU ignores CPUs in the inner idle loop (after the call to
> rcu_idle_enter()), RCU read-side critical sections are not legal there.
> 
> One approach would be to delay the call to rcu_idle_enter() until after
> the tracing is done, and to ensure that the call to rcu_idle_exit() happens
> before any tracing.  I am not seeing perf_trace_power(), so need to
> update and look again.  Or are you looking at -next rather than mainline?
> 

I am using mainline, not -next

It seems "powertop" triggers the warnings.

Check include/trace/events/power.h line 75 :

DECLARE_EVENT_CLASS(power,

This declares perf_trace_power()...

include/trace/ftrace.h line 718

#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)  \
static notrace void							\
perf_trace_##call(void *__data, proto) ...


Thanks


--
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/