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From: Joel Fernandes <joel@joelfernandes.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	rostedt@goodmis.org, mingo@kernel.org,
	gregkh@linuxfoundation.org, gustavo@embeddedor.com,
	tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org,
	mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com
Subject: Re: [PATCH v2 2/9] rcu: Mark rcu_dynticks_curr_cpu_in_eqs() inline
Date: Wed, 12 Feb 2020 17:38:18 -0500	[thread overview]
Message-ID: <20200212223818.GA115917@google.com> (raw)
In-Reply-To: <20200212210749.915180520@infradead.org>

On Wed, Feb 12, 2020 at 10:01:41PM +0100, Peter Zijlstra wrote:
> Since rcu_is_watching() is notrace (and needs to be, as it can be
> called from the tracers), make sure everything it in turn calls is
> notrace too.
> 
> To that effect, mark rcu_dynticks_curr_cpu_in_eqs() inline, which
> implies notrace, as the function is tiny.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
>  kernel/rcu/tree.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -294,7 +294,7 @@ static void rcu_dynticks_eqs_online(void
>   *
>   * No ordering, as we are sampling CPU-local information.
>   */
> -static bool rcu_dynticks_curr_cpu_in_eqs(void)
> +static inline bool rcu_dynticks_curr_cpu_in_eqs(void)

I think there are ways to turn off function inlining, such as gcc's:
-fkeep-inline-functions

And just to be sure weird compilers (clang *cough*) don't screw this up,
could we make it static inline notrace?

Build tested it on the tip tree on top of your patch:

---8<-----------------------

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index f3cb824fe5bbf..078d56951c8e7 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -294,7 +294,7 @@ static void rcu_dynticks_eqs_online(void)
  *
  * No ordering, as we are sampling CPU-local information.
  */
-static inline bool rcu_dynticks_curr_cpu_in_eqs(void)
+static inline notrace bool rcu_dynticks_curr_cpu_in_eqs(void)
 {
 	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 

  reply	other threads:[~2020-02-12 22:38 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12 21:01 [PATCH v2 0/9] tracing vs rcu vs nmi Peter Zijlstra
2020-02-12 21:01 ` [PATCH v2 1/9] rcu: Rename rcu_irq_{enter,exit}_irqson() Peter Zijlstra
2020-02-12 22:38   ` Joel Fernandes
2020-02-12 21:01 ` [PATCH v2 2/9] rcu: Mark rcu_dynticks_curr_cpu_in_eqs() inline Peter Zijlstra
2020-02-12 22:38   ` Joel Fernandes [this message]
2020-02-13  1:41     ` Steven Rostedt
2020-02-13 14:25       ` Joel Fernandes
2020-02-12 21:01 ` [PATCH v2 3/9] rcu,tracing: Create trace_rcu_{enter,exit}() Peter Zijlstra
2020-02-12 23:20   ` Joel Fernandes
2020-02-13  8:27     ` Peter Zijlstra
2020-02-13 13:31       ` Joel Fernandes
2020-02-13 13:51       ` Paul E. McKenney
2020-02-13 16:40         ` Peter Zijlstra
2020-02-13 18:56           ` Paul E. McKenney
2020-02-13 20:44             ` Joel Fernandes
2020-02-13 20:54               ` Paul E. McKenney
2020-02-13 21:19                 ` Joel Fernandes
2020-02-13 21:38                   ` Steven Rostedt
2020-02-13 21:50                     ` Paul E. McKenney
2020-02-13 22:04                       ` Steven Rostedt
2020-02-13 22:39                         ` Paul E. McKenney
2020-02-14  6:19                           ` Masami Hiramatsu
2020-02-15 14:59                             ` Paul E. McKenney
2020-02-17  8:55                               ` Masami Hiramatsu
2020-02-17 16:31                                 ` Paul E. McKenney
2020-02-18  4:33                                   ` Masami Hiramatsu
2020-02-18 16:12                                     ` Paul E. McKenney
2020-02-18 16:15                                       ` Mathieu Desnoyers
2020-02-18 16:35                                       ` Steven Rostedt
2020-02-18 17:46                                     ` Steven Rostedt
2020-02-18 20:18                                       ` Paul E. McKenney
2020-02-19  2:45                                         ` Masami Hiramatsu
2020-03-06 18:01                                           ` Masami Hiramatsu
2020-03-06 18:47                                             ` Joel Fernandes
2020-03-06 19:11                                             ` Joel Fernandes
2020-03-07  1:58                                               ` Masami Hiramatsu
2020-03-06  0:42                     ` Thomas Gleixner
2020-02-13 21:48                   ` Paul E. McKenney
2020-02-13 22:58                     ` Joel Fernandes
2020-02-13 23:55                       ` Steven Rostedt
2020-02-18 19:58               ` Peter Zijlstra
2020-02-18 20:17                 ` Paul E. McKenney
2020-02-18 20:40                   ` Peter Zijlstra
2020-02-18 21:39                     ` Paul E. McKenney
2020-02-19  9:57                       ` Peter Zijlstra
2020-02-19 12:46                         ` Paul E. McKenney
2020-02-12 23:27   ` Joel Fernandes
2020-02-13  8:28     ` Peter Zijlstra
2020-02-13 18:39       ` Joel Fernandes
2020-02-12 21:01 ` [PATCH v2 4/9] sched,rcu,tracing: Avoid tracing before in_nmi() is correct Peter Zijlstra
2020-02-12 21:01 ` [PATCH v2 5/9] x86,tracing: Add comments to do_nmi() Peter Zijlstra
2020-02-12 21:01 ` [PATCH v2 6/9] perf,tracing: Prepare the perf-trace interface for RCU changes Peter Zijlstra
2020-02-12 23:28   ` Joel Fernandes
2020-02-13  8:29     ` Peter Zijlstra
2020-02-13 18:38       ` Joel Fernandes
2020-02-12 21:01 ` [PATCH v2 7/9] tracing: Employ trace_rcu_{enter,exit}() Peter Zijlstra
2020-02-12 21:01 ` [PATCH v2 8/9] tracing: Remove regular RCU context for _rcuidle tracepoints (again) Peter Zijlstra
2020-02-12 21:01 ` [PATCH v2 9/9] perf,tracing: Allow function tracing when !RCU Peter Zijlstra
2020-02-14  2:28   ` Sergey Senozhatsky
2020-02-14  2:42     ` Sergey Senozhatsky
2020-02-14  3:32       ` Steven Rostedt
2020-02-14 20:38   ` Kim Phillips
2020-02-14 22:48     ` Steven Rostedt

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