From: Petr Mladek <pmladek@suse.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: gor@linux.ibm.com, jpoimboe@redhat.com, jikos@kernel.org,
mbenes@suse.cz, mingo@kernel.org, linux-kernel@vger.kernel.org,
joe.lawrence@redhat.com, fweisbec@gmail.com, tglx@linutronix.de,
hca@linux.ibm.com, svens@linux.ibm.com, sumanthk@linux.ibm.com,
live-patching@vger.kernel.org, paulmck@kernel.org
Subject: Re: [RFC][PATCH 6/7] context_tracking: Provide SMP ordering using RCU
Date: Thu, 23 Sep 2021 14:10:01 +0200 [thread overview]
Message-ID: <YUxumRtz7o/fKYri@alley> (raw)
In-Reply-To: <20210922110836.244770922@infradead.org>
On Wed 2021-09-22 13:05:12, Peter Zijlstra wrote:
> Use rcu_user_{enter,exit}() calls to provide SMP ordering on context
> tracking state stores:
>
> __context_tracking_exit()
> __this_cpu_write(context_tracking.state, CONTEXT_KERNEL)
> rcu_user_exit()
> rcu_eqs_exit()
> rcu_dynticks_eqs_eit()
> rcu_dynticks_inc()
> atomic_add_return() /* smp_mb */
>
> __context_tracking_enter()
> rcu_user_enter()
> rcu_eqs_enter()
> rcu_dynticks_eqs_enter()
> rcu_dynticks_inc()
> atomic_add_return() /* smp_mb */
> __this_cpu_write(context_tracking.state, state)
>
> This separates USER/KERNEL state with an smp_mb() on each side,
> therefore, a user of context_tracking_state_cpu() can say the CPU must
> pass through an smp_mb() before changing.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> include/linux/context_tracking_state.h | 12 ++++++++++++
> kernel/context_tracking.c | 7 ++++---
> 2 files changed, 16 insertions(+), 3 deletions(-)
>
> --- a/include/linux/context_tracking_state.h
> +++ b/include/linux/context_tracking_state.h
> @@ -45,11 +45,23 @@ static __always_inline bool context_trac
> {
> return __this_cpu_read(context_tracking.state) == CONTEXT_USER;
> }
> +
> +static __always_inline bool context_tracking_state_cpu(int cpu)
> +{
> + struct context_tracking *ct = per_cpu_ptr(&context_tracking);
Missing cpu parameter:
struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
> +
> + if (!context_tracking_enabled() || !ct->active)
> + return CONTEXT_DISABLED;
> +
> + return ct->state;
> +}
Best Regards,
Petr
next prev parent reply other threads:[~2021-09-23 12:10 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 11:05 [RFC][PATCH 0/7] sched,rcu,context_tracking,livepatch: Improve livepatch task transitions for idle and NOHZ_FULL cpus Peter Zijlstra
2021-09-22 11:05 ` [RFC][PATCH 1/7] sched,rcu: Rework try_invoke_on_locked_down_task() Peter Zijlstra
2021-09-22 11:05 ` [RFC][PATCH 2/7] sched: Fix task_try_func() Peter Zijlstra
2021-09-22 11:05 ` [RFC][PATCH 3/7] sched,livepatch: Use task_try_func() Peter Zijlstra
2021-09-23 12:05 ` Petr Mladek
2021-09-23 13:17 ` Peter Zijlstra
2021-09-23 13:47 ` Peter Zijlstra
2021-09-22 11:05 ` [RFC][PATCH 4/7] sched: Simplify wake_up_*idle*() Peter Zijlstra
2021-09-22 11:05 ` [RFC][PATCH 5/7] sched,livepatch: Use wake_up_if_idle() Peter Zijlstra
2021-09-22 13:05 ` Miroslav Benes
2021-09-23 12:19 ` Petr Mladek
2021-09-22 11:05 ` [RFC][PATCH 6/7] context_tracking: Provide SMP ordering using RCU Peter Zijlstra
2021-09-22 15:17 ` Paul E. McKenney
2021-09-22 19:33 ` Peter Zijlstra
2021-09-22 19:47 ` Peter Zijlstra
2021-09-22 19:59 ` Paul E. McKenney
2021-09-22 19:53 ` Paul E. McKenney
2021-09-22 20:02 ` Peter Zijlstra
2021-09-23 12:10 ` Petr Mladek [this message]
2021-09-24 18:57 ` Joel Savitz
2021-09-27 14:33 ` Petr Mladek
2021-09-22 11:05 ` [RFC][PATCH 7/7] livepatch,context_tracking: Avoid disturbing NOHZ_FULL tasks Peter Zijlstra
2021-09-23 13:14 ` Petr Mladek
2021-09-23 13:28 ` Peter Zijlstra
2021-09-24 7:33 ` Petr Mladek
2021-09-23 13:22 ` [RFC][PATCH 0/7] sched,rcu,context_tracking,livepatch: Improve livepatch task transitions for idle and NOHZ_FULL cpus Petr Mladek
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