From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> To: Valentin Schneider <valentin.schneider@arm.com> Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, rcu@vger.kernel.org, linux-rt-users@vger.kernel.org, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, Steven Rostedt <rostedt@goodmis.org>, Daniel Bristot de Oliveira <bristot@redhat.com>, "Paul E. McKenney" <paulmck@kernel.org>, Frederic Weisbecker <frederic@kernel.org>, Josh Triplett <josh@joshtriplett.org>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Davidlohr Bueso <dave@stgolabs.net>, Lai Jiangshan <jiangshanlai@gmail.com>, Joel Fernandes <joel@joelfernandes.org>, Anshuman Khandual <anshuman.khandual@arm.com>, Vincenzo Frascino <vincenzo.frascino@arm.com>, Steven Price <steven.price@arm.com>, Ard Biesheuvel <ardb@kernel.org>, Boqun Feng <boqun.feng@gmail.com>, Mike Galbraith <efault@gmx.de> Subject: Re: [PATCH v3 3/4] rcu/nocb: Protect NOCB state via local_lock() under PREEMPT_RT Date: Tue, 17 Aug 2021 17:36:13 +0200 [thread overview] Message-ID: <20210817153613.l5f66czar6pajexo@linutronix.de> (raw) In-Reply-To: <20210811201354.1976839-4-valentin.schneider@arm.com> On 2021-08-11 21:13:53 [+0100], Valentin Schneider wrote: > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index 0ff5e4fb933e..11c4ff00afde 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -21,6 +21,17 @@ static inline int rcu_lockdep_is_held_nocb(struct rcu_data *rdp) > return lockdep_is_held(&rdp->nocb_lock); > } > > +static inline int rcu_lockdep_is_held_nocb_local(struct rcu_data *rdp) > +{ > + return lockdep_is_held( > +#ifdef CONFIG_PREEMPT_RT > + &rdp->nocb_local_lock.lock > +#else > + &rdp->nocb_local_lock > +#endif > + ); > +} Now that I see it and Paul asked for it, please just use !RT version. return lockdep_is_held(&rdp->nocb_local_lock); and RT will work, too. > static inline bool rcu_current_is_nocb_kthread(struct rcu_data *rdp) > { > /* Race on early boot between thread creation and assignment */ > @@ -1629,6 +1664,22 @@ static void rcu_nocb_unlock_irqrestore(struct rcu_data *rdp, > } > } > > +/* > + * The invocation of rcu_core() within the RCU core kthreads remains preemptible > + * under PREEMPT_RT, thus the offload state of a CPU could change while > + * said kthreads are preempted. Prevent this from happening by protecting the > + * offload state with a local_lock(). > + */ > +static void rcu_nocb_local_lock(struct rcu_data *rdp) > +{ > + local_lock(&rcu_data.nocb_local_lock); > +} > + > +static void rcu_nocb_local_unlock(struct rcu_data *rdp) > +{ > + local_unlock(&rcu_data.nocb_local_lock); > +} > + Do you need to pass rdp given that it is not used? > /* Lockdep check that ->cblist may be safely accessed. */ > static void rcu_lockdep_assert_cblist_protected(struct rcu_data *rdp) > { Sebastian
WARNING: multiple messages have this Message-ID (diff)
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> To: Valentin Schneider <valentin.schneider@arm.com> Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, rcu@vger.kernel.org, linux-rt-users@vger.kernel.org, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, Steven Rostedt <rostedt@goodmis.org>, Daniel Bristot de Oliveira <bristot@redhat.com>, "Paul E. McKenney" <paulmck@kernel.org>, Frederic Weisbecker <frederic@kernel.org>, Josh Triplett <josh@joshtriplett.org>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Davidlohr Bueso <dave@stgolabs.net>, Lai Jiangshan <jiangshanlai@gmail.com>, Joel Fernandes <joel@joelfernandes.org>, Anshuman Khandual <anshuman.khandual@arm.com>, Vincenzo Frascino <vincenzo.frascino@arm.com>, Steven Price <steven.price@arm.com>, Ard Biesheuvel <ardb@kernel.org>, Boqun Feng <boqun.feng@gmail.com>, Mike Galbraith <efault@gmx.de> Subject: Re: [PATCH v3 3/4] rcu/nocb: Protect NOCB state via local_lock() under PREEMPT_RT Date: Tue, 17 Aug 2021 17:36:13 +0200 [thread overview] Message-ID: <20210817153613.l5f66czar6pajexo@linutronix.de> (raw) In-Reply-To: <20210811201354.1976839-4-valentin.schneider@arm.com> On 2021-08-11 21:13:53 [+0100], Valentin Schneider wrote: > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index 0ff5e4fb933e..11c4ff00afde 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -21,6 +21,17 @@ static inline int rcu_lockdep_is_held_nocb(struct rcu_data *rdp) > return lockdep_is_held(&rdp->nocb_lock); > } > > +static inline int rcu_lockdep_is_held_nocb_local(struct rcu_data *rdp) > +{ > + return lockdep_is_held( > +#ifdef CONFIG_PREEMPT_RT > + &rdp->nocb_local_lock.lock > +#else > + &rdp->nocb_local_lock > +#endif > + ); > +} Now that I see it and Paul asked for it, please just use !RT version. return lockdep_is_held(&rdp->nocb_local_lock); and RT will work, too. > static inline bool rcu_current_is_nocb_kthread(struct rcu_data *rdp) > { > /* Race on early boot between thread creation and assignment */ > @@ -1629,6 +1664,22 @@ static void rcu_nocb_unlock_irqrestore(struct rcu_data *rdp, > } > } > > +/* > + * The invocation of rcu_core() within the RCU core kthreads remains preemptible > + * under PREEMPT_RT, thus the offload state of a CPU could change while > + * said kthreads are preempted. Prevent this from happening by protecting the > + * offload state with a local_lock(). > + */ > +static void rcu_nocb_local_lock(struct rcu_data *rdp) > +{ > + local_lock(&rcu_data.nocb_local_lock); > +} > + > +static void rcu_nocb_local_unlock(struct rcu_data *rdp) > +{ > + local_unlock(&rcu_data.nocb_local_lock); > +} > + Do you need to pass rdp given that it is not used? > /* Lockdep check that ->cblist may be safely accessed. */ > static void rcu_lockdep_assert_cblist_protected(struct rcu_data *rdp) > { Sebastian _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-08-17 15:36 UTC|newest] Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-08-11 20:13 [PATCH v3 0/4] rcu, arm64: PREEMPT_RT fixlets Valentin Schneider 2021-08-11 20:13 ` Valentin Schneider 2021-08-11 20:13 ` [PATCH v3 1/4] rcutorture: Don't disable softirqs with preemption disabled when PREEMPT_RT Valentin Schneider 2021-08-11 20:13 ` Valentin Schneider 2021-08-12 16:47 ` Paul E. McKenney 2021-08-12 16:47 ` Paul E. McKenney 2021-08-17 12:13 ` Sebastian Andrzej Siewior 2021-08-17 12:13 ` Sebastian Andrzej Siewior 2021-08-17 13:17 ` Sebastian Andrzej Siewior 2021-08-17 13:17 ` Sebastian Andrzej Siewior 2021-08-17 14:40 ` [PATCH] rcutorture: Avoid problematic critical section nesting on RT Sebastian Andrzej Siewior 2021-08-17 14:40 ` Sebastian Andrzej Siewior 2021-08-18 22:46 ` Paul E. McKenney 2021-08-18 22:46 ` Paul E. McKenney 2021-08-19 15:35 ` Sebastian Andrzej Siewior 2021-08-19 15:35 ` Sebastian Andrzej Siewior 2021-08-19 15:39 ` Sebastian Andrzej Siewior 2021-08-19 15:39 ` Sebastian Andrzej Siewior 2021-08-19 15:47 ` Sebastian Andrzej Siewior 2021-08-19 15:47 ` Sebastian Andrzej Siewior 2021-08-19 18:20 ` Paul E. McKenney 2021-08-19 18:20 ` Paul E. McKenney 2021-08-19 18:45 ` Sebastian Andrzej Siewior 2021-08-19 18:45 ` Sebastian Andrzej Siewior 2021-08-20 4:11 ` Scott Wood 2021-08-20 4:11 ` Scott Wood 2021-08-20 7:11 ` Sebastian Andrzej Siewior 2021-08-20 7:11 ` Sebastian Andrzej Siewior 2021-08-20 7:42 ` [PATCH v2] rcutorture: Avoid problematic critical section nesting on PREEMPT_RT Sebastian Andrzej Siewior 2021-08-20 7:42 ` Sebastian Andrzej Siewior 2021-08-20 22:10 ` Paul E. McKenney 2021-08-20 22:10 ` Paul E. McKenney 2021-08-20 3:23 ` [PATCH] rcutorture: Avoid problematic critical section nesting on RT Scott Wood 2021-08-20 3:23 ` Scott Wood 2021-08-20 6:54 ` Sebastian Andrzej Siewior 2021-08-20 6:54 ` Sebastian Andrzej Siewior 2021-08-11 20:13 ` [PATCH v3 2/4] sched: Introduce migratable() Valentin Schneider 2021-08-11 20:13 ` Valentin Schneider 2021-08-17 14:43 ` Sebastian Andrzej Siewior 2021-08-17 14:43 ` Sebastian Andrzej Siewior 2021-08-22 17:31 ` Valentin Schneider 2021-08-22 17:31 ` Valentin Schneider 2021-08-17 17:09 ` Sebastian Andrzej Siewior 2021-08-17 17:09 ` Sebastian Andrzej Siewior 2021-08-17 19:30 ` Phil Auld 2021-08-17 19:30 ` Phil Auld 2021-08-22 18:14 ` Valentin Schneider 2021-08-22 18:14 ` Valentin Schneider 2022-01-26 16:56 ` Sebastian Andrzej Siewior 2022-01-26 16:56 ` Sebastian Andrzej Siewior 2022-01-26 18:10 ` Valentin Schneider 2022-01-26 18:10 ` Valentin Schneider 2022-01-27 10:07 ` Sebastian Andrzej Siewior 2022-01-27 10:07 ` Sebastian Andrzej Siewior 2022-01-27 18:23 ` Valentin Schneider 2022-01-27 18:23 ` Valentin Schneider 2022-01-27 19:27 ` Valentin Schneider 2022-01-27 19:27 ` Valentin Schneider 2022-02-04 9:24 ` Sebastian Andrzej Siewior 2022-02-04 9:24 ` Sebastian Andrzej Siewior 2021-08-11 20:13 ` [PATCH v3 3/4] rcu/nocb: Protect NOCB state via local_lock() under PREEMPT_RT Valentin Schneider 2021-08-11 20:13 ` Valentin Schneider 2021-08-13 0:20 ` Paul E. McKenney 2021-08-13 0:20 ` Paul E. McKenney 2021-08-13 18:48 ` Valentin Schneider 2021-08-13 18:48 ` Valentin Schneider 2021-08-24 13:00 ` Frederic Weisbecker 2021-08-17 15:36 ` Sebastian Andrzej Siewior [this message] 2021-08-17 15:36 ` Sebastian Andrzej Siewior 2021-08-22 18:15 ` Valentin Schneider 2021-08-22 18:15 ` Valentin Schneider 2021-09-21 14:05 ` Thomas Gleixner 2021-09-21 14:05 ` Thomas Gleixner 2021-09-21 21:12 ` rcu/tree: Protect rcu_rdp_is_offloaded() invocations on RT Thomas Gleixner 2021-09-21 23:36 ` Frederic Weisbecker 2021-09-21 23:36 ` Frederic Weisbecker 2021-09-22 2:18 ` Paul E. McKenney 2021-09-22 2:18 ` Paul E. McKenney 2021-09-22 11:31 ` Frederic Weisbecker 2021-09-22 11:31 ` Frederic Weisbecker 2021-09-21 23:45 ` Frederic Weisbecker 2021-09-21 23:45 ` Frederic Weisbecker 2021-09-22 6:32 ` Sebastian Andrzej Siewior 2021-09-22 6:32 ` Sebastian Andrzej Siewior 2021-09-22 11:10 ` Frederic Weisbecker 2021-09-22 11:10 ` Frederic Weisbecker 2021-09-22 11:27 ` Sebastian Andrzej Siewior 2021-09-22 11:27 ` Sebastian Andrzej Siewior 2021-09-22 11:38 ` Frederic Weisbecker 2021-09-22 11:38 ` Frederic Weisbecker 2021-09-22 13:02 ` Sebastian Andrzej Siewior 2021-09-22 13:02 ` Sebastian Andrzej Siewior 2021-09-23 10:02 ` Frederic Weisbecker 2021-09-23 10:02 ` Frederic Weisbecker 2021-09-30 9:00 ` Valentin Schneider 2021-09-30 9:00 ` Valentin Schneider 2021-09-30 10:53 ` Frederic Weisbecker 2021-09-30 10:53 ` Frederic Weisbecker 2021-09-30 13:22 ` Valentin Schneider 2021-09-30 13:22 ` Valentin Schneider 2021-08-11 20:13 ` [PATCH v3 4/4] arm64: mm: Make arch_faults_on_old_pte() check for migratability Valentin Schneider 2021-08-11 20:13 ` Valentin Schneider
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