Re: [PATCH 0/3 v3] rcu: Detect rcu uses under extended quiescentstate

From: Frederic Weisbecker
Date: Fri Jun 24 2011 - 07:48:46 EST


On Fri, Jun 24, 2011 at 11:18:45AM +0200, Peter Zijlstra wrote:
> On Fri, 2011-06-24 at 01:12 +0200, Frederic Weisbecker wrote:
> > This time I have no current practical cases to fix. Those I fixed
> > in previous versions were actually using rcu_dereference_raw(), which
> > is legal in extended qs.
> >
> > Frederic Weisbecker (3):
> > rcu: Detect illegal rcu dereference in extended quiescent state
> > rcu: Inform the user about dynticks idle mode on PROVE_RCU warning
> > rcu: Warn when rcu_read_lock() is used in extended quiescent state
> >
> > include/linux/rcupdate.h | 68 +++++++++++++++++++++++++++++++++++++++-------
> > kernel/lockdep.c | 4 +++
> > kernel/rcupdate.c | 4 +++
> > kernel/rcutiny.c | 13 +++++++++
> > kernel/rcutree.c | 14 +++++++++
> > 5 files changed, 93 insertions(+), 10 deletions(-)
>
> Right, so the only comment I have is that it might have been nice to
> explain what the heck an extended qs is :-) I've since figured it out,
> but it did require waking up my brain.

Hehe, right :)

As I have scratched my head for some times with rcu dynticks for the nohz cpuset
things, I guess that in the meantime my unconscious mind developed the idea that rcu extended
quiescent states were a worldwide topic that every people talk about in dinner with their family,
that these even became the core stories of some lullabies. I can still hear its chorus, that makes
one switching to idle peacefully...
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