Messages in this thread |  | | Date | Tue, 24 Nov 2020 17:13:35 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH -tip 19/32] entry/idle: Enter and exit kernel protection during idle entry and exit |
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On Tue, Nov 17, 2020 at 06:19:49PM -0500, Joel Fernandes (Google) wrote: > Add a generic_idle_{enter,exit} helper function to enter and exit kernel > protection when entering and exiting idle, respectively. > > While at it, remove a stale RCU comment. > > Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> > Tested-by: Julien Desfossez <jdesfossez@digitalocean.com> > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> > --- > include/linux/entry-common.h | 18 ++++++++++++++++++ > kernel/sched/idle.c | 11 ++++++----- > 2 files changed, 24 insertions(+), 5 deletions(-) > > diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h > index 022e1f114157..8f34ae625f83 100644 > --- a/include/linux/entry-common.h > +++ b/include/linux/entry-common.h > @@ -454,4 +454,22 @@ static inline bool entry_kernel_protected(void) > return IS_ENABLED(CONFIG_SCHED_CORE) && sched_core_kernel_protected() > && _TIF_UNSAFE_RET != 0; > } > + > +/** > + * generic_idle_enter - General tasks to perform during idle entry. > + */ > +static inline void generic_idle_enter(void) > +{ > + /* Entering idle ends the protected kernel region. */ > + sched_core_unsafe_exit(); > +} > + > +/** > + * generic_idle_exit - General tasks to perform during idle exit. > + */ > +static inline void generic_idle_exit(void) > +{ > + /* Exiting idle (re)starts the protected kernel region. */ > + sched_core_unsafe_enter(); > +} > #endif
That naming is terrible..
> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c > index 8bdb214eb78f..ee4f91396c31 100644 > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -8,6 +8,7 @@ > */ > #include "sched.h" > > +#include <linux/entry-common.h> > #include <trace/events/power.h> > > /* Linker adds these: start and end of __cpuidle functions */ > @@ -54,6 +55,7 @@ __setup("hlt", cpu_idle_nopoll_setup); > > static noinline int __cpuidle cpu_idle_poll(void) > { > + generic_idle_enter(); > trace_cpu_idle(0, smp_processor_id()); > stop_critical_timings(); > rcu_idle_enter(); > @@ -66,6 +68,7 @@ static noinline int __cpuidle cpu_idle_poll(void) > rcu_idle_exit(); > start_critical_timings(); > trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id()); > + generic_idle_exit(); > > return 1; > } > @@ -156,11 +159,7 @@ static void cpuidle_idle_call(void) > return; > } > > - /* > - * The RCU framework needs to be told that we are entering an idle > - * section, so no more rcu read side critical sections and one more > - * step to the grace period > - */ > + generic_idle_enter(); > > if (cpuidle_not_available(drv, dev)) { > tick_nohz_idle_stop_tick(); > @@ -225,6 +224,8 @@ static void cpuidle_idle_call(void) > */ > if (WARN_ON_ONCE(irqs_disabled())) > local_irq_enable(); > + > + generic_idle_exit(); > }
I'm confused.. arch_cpu_idle_{enter,exit}() weren't conveniently placed for you?
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