From: Peter Zijlstra <peterz@infradead.org>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: tglx@linutronix.de, pbonzini@redhat.com, bigeasy@linutronix.de,
rostedt@goodmis.org, torvalds@linux-foundation.org,
will@kernel.org, joel@joelfernandes.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH 3/5] rcuwait: Introduce prepare_to and finish_rcuwait
Date: Thu, 23 Apr 2020 11:23:14 +0200 [thread overview]
Message-ID: <20200423092314.GQ20730@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200422040739.18601-4-dave@stgolabs.net>
On Tue, Apr 21, 2020 at 09:07:37PM -0700, Davidlohr Bueso wrote:
> +static inline void prepare_to_rcuwait(struct rcuwait *w)
> +{
> + rcu_assign_pointer(w->task, current);
> +}
> +
> +static inline void finish_rcuwait(struct rcuwait *w)
> +{
> + WRITE_ONCE(w->task, NULL);
I think that wants to be:
rcu_assign_pointer(w->task, NULL);
There is a special case in rcu_assign_pointer() that looses the barrier,
but it will keep the __rcu sparse people happy. That is w->task is
__rcu, and WRITE_ONCE ignores that etc.. blah.
The alternative is using RCU_INIT_POINTER() I suppose.
> + __set_current_state(TASK_RUNNING);
> +}
next prev parent reply other threads:[~2020-04-23 9:23 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 4:07 [PATCH v3 -tip 0/5] kvm: Use rcuwait for vcpu blocking Davidlohr Bueso
2020-04-22 4:07 ` [PATCH 1/5] rcuwait: Fix stale wake call name in comment Davidlohr Bueso
2020-04-22 4:07 ` [PATCH 2/5] rcuwait: Let rcuwait_wake_up() return whether or not a task was awoken Davidlohr Bueso
2020-04-22 4:07 ` [PATCH 3/5] rcuwait: Introduce prepare_to and finish_rcuwait Davidlohr Bueso
2020-04-23 9:23 ` Peter Zijlstra [this message]
2020-04-22 4:07 ` [PATCH 4/5] kvm: Replace vcpu->swait with rcuwait Davidlohr Bueso
2020-04-22 8:32 ` Paolo Bonzini
2020-04-22 10:14 ` Marc Zyngier
2020-04-23 8:41 ` Marc Zyngier
2020-04-23 8:57 ` Paolo Bonzini
2020-04-23 9:19 ` Peter Zijlstra
2020-04-23 9:26 ` Paolo Bonzini
2020-04-22 4:07 ` [PATCH 5/5] sched/swait: Reword some of the main description Davidlohr Bueso
2020-05-01 18:22 ` [tip: sched/core] " tip-bot2 for Davidlohr Bueso
2020-04-22 11:33 ` [PATCH v3 -tip 0/5] kvm: Use rcuwait for vcpu blocking Peter Zijlstra
-- strict thread matches above, loose matches on Subject: below --
2020-04-24 5:48 [PATCH v4 " Davidlohr Bueso
2020-04-24 5:48 ` [PATCH 3/5] rcuwait: Introduce prepare_to and finish_rcuwait Davidlohr Bueso
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