From: "Paul E. McKenney" <paulmck@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Frederic Weisbecker <frederic@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>,
Joel Fernandes <joel@joelfernandes.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>, Brian Gerst <brgerst@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Will Deacon <will@kernel.org>
Subject: Re: [patch V4 part 3 11/29] rcu: Provide rcu_irq_exit_preempt()
Date: Tue, 5 May 2020 15:02:24 -0700 [thread overview]
Message-ID: <20200505220224.GT2869@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <20200505134904.364456424@linutronix.de>
On Tue, May 05, 2020 at 03:44:05PM +0200, Thomas Gleixner wrote:
> Interrupts and exceptions invoke rcu_irq_enter() on entry and need to
> invoke rcu_irq_exit() before they either return to the interrupted code or
> invoke the scheduler due to preemption.
>
> The general assumption is that RCU idle code has to have preemption
> disabled so that a return from interrupt cannot schedule. So the return
> from interrupt code invokes rcu_irq_exit() and preempt_schedule_irq().
>
> If there is any imbalance in the rcu_irq/nmi* invocations or RCU idle code
> had preemption enabled then this goes unnoticed until the CPU goes idle or
> some other RCU check is executed.
>
> Provide rcu_irq_exit_preempt() which can be invoked from the
> interrupt/exception return code in case that preemption is enabled. It
> invokes rcu_irq_exit() and contains a few sanity checks in case that
> CONFIG_PROVE_RCU is enabled to catch such issues directly.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: "Paul E. McKenney" <paulmck@kernel.org>
> Cc: Joel Fernandes <joel@joelfernandes.org>
The ->dynticks_nmi_nesting field is going away at some point, but
there is always "git merge". ;-)
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
> ---
> include/linux/rcutiny.h | 1 +
> include/linux/rcutree.h | 1 +
> kernel/rcu/tree.c | 21 +++++++++++++++++++++
> 3 files changed, 23 insertions(+)
>
> --- a/include/linux/rcutiny.h
> +++ b/include/linux/rcutiny.h
> @@ -71,6 +71,7 @@ static inline void rcu_irq_enter(void) {
> static inline void rcu_irq_exit_irqson(void) { }
> static inline void rcu_irq_enter_irqson(void) { }
> static inline void rcu_irq_exit(void) { }
> +static inline void rcu_irq_exit_preempt(void) { }
> static inline void exit_rcu(void) { }
> static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
> {
> --- a/include/linux/rcutree.h
> +++ b/include/linux/rcutree.h
> @@ -46,6 +46,7 @@ void rcu_idle_enter(void);
> void rcu_idle_exit(void);
> void rcu_irq_enter(void);
> void rcu_irq_exit(void);
> +void rcu_irq_exit_preempt(void);
> void rcu_irq_enter_irqson(void);
> void rcu_irq_exit_irqson(void);
>
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -706,6 +706,27 @@ void noinstr rcu_irq_exit(void)
> rcu_nmi_exit();
> }
>
> +/**
> + * rcu_irq_exit_preempt - Inform RCU that current CPU is exiting irq
> + * towards in kernel preemption
> + *
> + * Same as rcu_irq_exit() but has a sanity check that scheduling is safe
> + * from RCU point of view. Invoked from return from interrupt before kernel
> + * preemption.
> + */
> +void rcu_irq_exit_preempt(void)
> +{
> + lockdep_assert_irqs_disabled();
> + rcu_nmi_exit();
> +
> + RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) <= 0,
> + "RCU dynticks_nesting counter underflow/zero!");
> + RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 0,
> + "RCU dynticks_nmi_nesting counter underflow/zero!");
> + RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(),
> + "RCU in extended quiescent state!");
> +}
> +
> /*
> * Wrapper for rcu_irq_exit() where interrupts are enabled.
> *
>
next prev parent reply other threads:[~2020-05-05 22:02 UTC|newest]
Thread overview: 129+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 13:43 [patch V4 part 3 00/29] x86/entry: Entry/exception code rework, simple exceptions Thomas Gleixner
2020-05-05 13:43 ` [patch V4 part 3 01/29] x86/traps: Mark fixup_bad_iret() noinstr Thomas Gleixner
2020-05-09 0:39 ` Andy Lutomirski
2020-05-13 1:51 ` Steven Rostedt
2020-05-14 0:41 ` Mathieu Desnoyers
2020-05-14 1:35 ` Andy Lutomirski
2020-05-11 12:28 ` Masami Hiramatsu
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:43 ` [patch V4 part 3 02/29] x86/traps: Mark sync_regs() noinstr Thomas Gleixner
2020-05-09 0:39 ` Andy Lutomirski
2020-05-11 12:08 ` Masami Hiramatsu
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:43 ` [patch V4 part 3 03/29] x86/entry: Disable interrupts for native_load_gs_index() in C code Thomas Gleixner
2020-05-09 0:40 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:43 ` [patch V4 part 3 04/29] x86/traps: Make interrupt enable/disable symmetric " Thomas Gleixner
2020-05-07 15:25 ` Alexandre Chartre
2020-05-07 17:14 ` Thomas Gleixner
2020-05-09 0:44 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:43 ` [patch V4 part 3 05/29] x86/traps: Split trap numbers out in a seperate header Thomas Gleixner
2020-05-07 15:34 ` Alexandre Chartre
2020-05-19 19:58 ` [tip: x86/entry] x86/traps: Split trap numbers out in a separate header tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 06/29] x86/entry/64: Reorder idtentries Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 07/29] x86/entry: Distangle idtentry Thomas Gleixner
2020-05-10 20:31 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 08/29] x86/entry/64: Provide sane error entry/exit Thomas Gleixner
2020-05-10 21:02 ` Andy Lutomirski
2020-05-13 2:10 ` Steven Rostedt
2020-05-13 6:35 ` Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 09/29] x86/entry/32: Provide macro to emit IDT entry stubs Thomas Gleixner
2020-05-11 0:55 ` Andy Lutomirski
2020-05-14 1:44 ` Mathieu Desnoyers
2020-05-14 4:31 ` Andy Lutomirski
2020-05-14 13:38 ` Mathieu Desnoyers
2020-05-14 14:08 ` Thomas Gleixner
2020-05-14 14:43 ` Mathieu Desnoyers
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 10/29] x86/idtentry: Provide macros to define/declare IDT entry points Thomas Gleixner
2020-05-11 0:58 ` Andy Lutomirski
2020-05-11 10:39 ` Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 11/29] rcu: Provide rcu_irq_exit_preempt() Thomas Gleixner
2020-05-05 22:02 ` Paul E. McKenney [this message]
2020-05-05 22:05 ` Thomas Gleixner
2020-05-05 22:24 ` Paul E. McKenney
2020-05-14 1:03 ` Mathieu Desnoyers
2020-05-14 2:41 ` Joel Fernandes
2020-05-14 2:46 ` Joel Fernandes
2020-05-14 14:43 ` Thomas Gleixner
2020-05-15 19:00 ` Joel Fernandes
2020-05-19 19:52 ` [tip: core/rcu] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 12/29] x86/entry/common: Provide idtentry_enter/exit() Thomas Gleixner
2020-05-07 16:27 ` Alexandre Chartre
2020-05-11 4:34 ` Andy Lutomirski
2020-05-11 10:59 ` [patch V5 " Thomas Gleixner
2020-05-11 15:31 ` Andy Lutomirski
2020-05-11 18:42 ` Thomas Gleixner
2020-05-12 16:49 ` [patch V6 " Thomas Gleixner
2020-05-14 0:51 ` Andy Lutomirski
2020-05-14 1:08 ` [patch V4 " Mathieu Desnoyers
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 13/29] x86/traps: Prepare for using DEFINE_IDTENTRY Thomas Gleixner
2020-05-14 4:37 ` Andy Lutomirski
2020-05-14 12:16 ` Thomas Gleixner
2020-05-14 12:33 ` Peter Zijlstra
2020-05-15 13:42 ` Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 14/29] x86/entry: Convert Divide Error to IDTENTRY Thomas Gleixner
2020-05-14 4:38 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-10-11 15:25 ` Dmitry Vyukov
2020-10-11 17:50 ` Thomas Gleixner
2020-10-12 13:19 ` [tip: x86/urgent] x86/traps: Fix #DE Oops message regression tip-bot2 for Thomas Gleixner
2020-10-12 20:30 ` [tip: x86/entry] x86/entry: Convert Divide Error to IDTENTRY Kees Cook
2020-10-13 10:19 ` Dmitry Vyukov
2020-10-13 17:41 ` [tip: x86/urgent] x86/traps: Fix #DE Oops message regression tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 15/29] x86/entry: Convert Overflow exception to IDTENTRY Thomas Gleixner
2020-05-14 4:39 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 16/29] x86/entry: Convert Bounds " Thomas Gleixner
2020-05-14 4:42 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 17/29] x86/entry: Convert Invalid Opcode " Thomas Gleixner
2020-05-14 4:45 ` Andy Lutomirski
2020-05-14 12:33 ` Thomas Gleixner
2020-05-14 15:00 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 18/29] x86/entry: Convert Device not available " Thomas Gleixner
2020-05-14 4:45 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 19/29] x86/entry: Convert Coprocessor segment overrun " Thomas Gleixner
2020-05-14 4:46 ` Andy Lutomirski
2020-05-05 13:44 ` [patch V4 part 3 20/29] x86/entry: Provide IDTENTRY_ERRORCODE Thomas Gleixner
2020-05-14 4:46 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] x86/idtentry: " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 21/29] x86/entry: Convert Invalid TSS exception to IDTENTRY Thomas Gleixner
2020-05-14 4:48 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 22/29] x86/entry: Convert Segment not present " Thomas Gleixner
2020-05-14 4:47 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 23/29] x86/entry: Convert Stack segment " Thomas Gleixner
2020-05-14 4:49 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 24/29] x86/entry: Convert General protection " Thomas Gleixner
2020-05-14 4:50 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 25/29] x86/entry: Convert Spurious interrupt bug " Thomas Gleixner
2020-05-14 4:47 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 26/29] x86/entry: Convert Coprocessor error " Thomas Gleixner
2020-05-14 4:49 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] x86/entry: Convert Coprocessor segment overrun " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 27/29] x86/entry: Convert Alignment check " Thomas Gleixner
2020-05-14 4:50 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 28/29] x86/entry: Convert SIMD coprocessor error " Thomas Gleixner
2020-05-14 4:56 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 29/29] x86/entry/32: Convert IRET exception to IDTENTRY_SW Thomas Gleixner
2020-05-07 16:47 ` Alexandre Chartre
2020-05-14 4:54 ` Andy Lutomirski
2020-05-15 14:11 ` Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
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