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SubjectRe: [PATCH 2/4] rcu: Irq nesting is always 0 on rcu_enter_idle_common
On Mon, Nov 28, 2011 at 04:29:14PM -0800, Paul E. McKenney wrote:
> On Mon, Nov 28, 2011 at 10:24:45PM +0100, Frederic Weisbecker wrote:
> > So pass 0 directly as a nesting value on the tracing calls.
> >
> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > Cc: Josh Triplett <josh@joshtriplett.org>
> > ---
> > kernel/rcutree.c | 5 ++---
> > 1 files changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> > index c2aaadf..b80cb41 100644
> > --- a/kernel/rcutree.c
> > +++ b/kernel/rcutree.c
> > @@ -350,11 +350,10 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp)
> > */
> > static void rcu_idle_enter_common(struct rcu_dynticks *rdtp)
> > {
> > - trace_rcu_dyntick("Start", rdtp->dynticks_nesting);
> > + trace_rcu_dyntick("Start", 0);
> > if (!idle_cpu(smp_processor_id())) {
> > WARN_ON_ONCE(1); /* must be idle task! */
> > - trace_rcu_dyntick("Error on entry: not idle task",
> > - rdtp->dynticks_nesting);
> > + trace_rcu_dyntick("Error on entry: not idle task", 0);
> > ftrace_dump(DUMP_ALL);
> > }
> > /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
>
> Queued, again updating to work around the mid-air collision.
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> rcu: Irq nesting is always 0 on rcu_enter_idle_common
>
> Because tasks don't nest, the ->dyntick_nesting must always be zero upon
> entry to rcu_idle_enter_common(). Therefore, pass "0" rather than the
> counter itself.

And with a better changelog.

Thanks!

>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Josh Triplett <josh@joshtriplett.org>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index 54d9b4f..e0f5072 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -350,12 +350,11 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp)
> */
> static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval)
> {
> - trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting);
> + trace_rcu_dyntick("Start", oldval, 0);
> if (!is_idle_task(current)) {
> struct task_struct *idle = idle_task(smp_processor_id());
>
> - trace_rcu_dyntick("Error on entry: not idle task",
> - oldval, rdtp->dynticks_nesting);
> + trace_rcu_dyntick("Error on entry: not idle task", oldval, 0);
> ftrace_dump(DUMP_ALL);
> WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
> current->pid, current->comm,
>


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