On Mon, Aug 19, 2019 at 07:46:32AM -0700, Paul E. McKenney wrote:
> On Mon, Aug 19, 2019 at 02:38:38PM +0200, Frederic Weisbecker wrote:
> > On Thu, Aug 15, 2019 at 10:53:09PM -0400, Joel Fernandes (Google) wrote:
> > > This commit fixes the issue.
> > >
> > > Signed-off-by: Joel Fernandes (Google) <j...@joelfernandes.org>
> > > ---
> > > kernel/rcu/tree.c | 29 +++++++++++++++++------------
> > > 1 file changed, 17 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > > index 0512de9ead20..322b1b57967c 100644
> > > --- a/kernel/rcu/tree.c
> > > +++ b/kernel/rcu/tree.c
> > > @@ -829,7 +829,7 @@ static __always_inline void rcu_nmi_enter_common(bool
> > > irq)
> > > !rdp->dynticks_nmi_nesting &&
> > > rdp->rcu_urgent_qs && !rdp->rcu_forced_tick) {
> > > rdp->rcu_forced_tick = true;
> > > - tick_dep_set_cpu(rdp->cpu, TICK_DEP_MASK_RCU);
> > > + tick_dep_set_cpu(rdp->cpu, TICK_DEP_BIT_RCU);
> >
> > Did I suggest you to use the _MASK_ value? That was a bit mean.
> > Sorry for all that lost debugging time :-(
>
> At some point, I should have looked at the other calls to these
> functions. :-/
>
> But would the following patch make sense? This would not help for (say)
> use of TICK_MASK_BIT_POSIX_TIMER instead of TICK_DEP_BIT_POSIX_TIMER, but
> would help for any new values that might be added later on. And currently
> for TICK_DEP_MASK_CLOCK_UNSTABLE and TICK_DEP_MASK_RCU.
I'd rather make the TICK_DEP_MASK_* values private to kernel/time/tick-sched.c
but
that means I need to re-arrange a bit include/trace/events/timer.h
I'm looking into it. Meanwhile, your below patch that checks for the max value
is
still valuable.
Thanks.
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> diff --git a/include/linux/tick.h b/include/linux/tick.h
> index 39eb44564058..4ed788ce5762 100644
> --- a/include/linux/tick.h
> +++ b/include/linux/tick.h
> @@ -111,6 +111,7 @@ enum tick_dep_bits {
> TICK_DEP_BIT_CLOCK_UNSTABLE = 3,
> TICK_DEP_BIT_RCU = 4
> };
> +#define TICK_DEP_BIT_MAX TICK_DEP_BIT_RCU
>
> #define TICK_DEP_MASK_NONE 0
> #define TICK_DEP_MASK_POSIX_TIMER (1 << TICK_DEP_BIT_POSIX_TIMER)
> @@ -215,24 +216,28 @@ extern void tick_nohz_dep_clear_signal(struct
> signal_struct *signal,
> */
> static inline void tick_dep_set(enum tick_dep_bits bit)
> {
> + WARN_ON_ONCE(bit > TICK_DEP_BIT_MAX);
> if (tick_nohz_full_enabled())
> tick_nohz_dep_set(bit);
> }
>
> static inline void tick_dep_clear(enum tick_dep_bits bit)
> {
> + WARN_ON_ONCE(bit > TICK_DEP_BIT_MAX);
> if (tick_nohz_full_enabled())
> tick_nohz_dep_clear(bit);
> }
>
> static inline void tick_dep_set_cpu(int cpu, enum tick_dep_bits bit)
> {
> + WARN_ON_ONCE(bit > TICK_DEP_BIT_MAX);
> if (tick_nohz_full_cpu(cpu))
> tick_nohz_dep_set_cpu(cpu, bit);
> }
>
> static inline void tick_dep_clear_cpu(int cpu, enum tick_dep_bits bit)
> {
> + WARN_ON_ONCE(bit > TICK_DEP_BIT_MAX);
> if (tick_nohz_full_cpu(cpu))
> tick_nohz_dep_clear_cpu(cpu, bit);
> }
> @@ -240,24 +245,28 @@ static inline void tick_dep_clear_cpu(int cpu, enum
> tick_dep_bits bit)
> static inline void tick_dep_set_task(struct task_struct *tsk,
> enum tick_dep_bits bit)
> {
> + WARN_ON_ONCE(bit > TICK_DEP_BIT_MAX);
> if (tick_nohz_full_enabled())
> tick_nohz_dep_set_task(tsk, bit);
> }
> static inline void tick_dep_clear_task(struct task_struct *tsk,
> enum tick_dep_bits bit)
> {
> + WARN_ON_ONCE(bit > TICK_DEP_BIT_MAX);
> if (tick_nohz_full_enabled())
> tick_nohz_dep_clear_task(tsk, bit);
> }
> static inline void tick_dep_set_signal(struct signal_struct *signal,
> enum tick_dep_bits bit)
> {
> + WARN_ON_ONCE(bit > TICK_DEP_BIT_MAX);
> if (tick_nohz_full_enabled())
> tick_nohz_dep_set_signal(signal, bit);
> }
> static inline void tick_dep_clear_signal(struct signal_struct *signal,
> enum tick_dep_bits bit)
> {
> + WARN_ON_ONCE(bit > TICK_DEP_BIT_MAX);
> if (tick_nohz_full_enabled())
> tick_nohz_dep_clear_signal(signal, bit);
> }
