lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <ZIddtMiTj8Kktq1z@boqun-archlinux>
Date:   Mon, 12 Jun 2023 11:02:28 -0700
From:   Boqun Feng <boqun.feng@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     torvalds@...ux-foundation.org, keescook@...omium.org,
        gregkh@...uxfoundation.org, pbonzini@...hat.com,
        masahiroy@...nel.org, nathan@...nel.org, ndesaulniers@...gle.com,
        nicolas@...sle.eu, catalin.marinas@....com, will@...nel.org,
        vkoul@...nel.org, trix@...hat.com, ojeda@...nel.org,
        mingo@...hat.com, longman@...hat.com, dennis@...nel.org,
        tj@...nel.org, cl@...ux.com, acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
        namhyung@...nel.org, irogers@...gle.com, adrian.hunter@...el.com,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com,
        paulmck@...nel.org, frederic@...nel.org, quic_neeraju@...cinc.com,
        joel@...lfernandes.org, josh@...htriplett.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com,
        rientjes@...gle.com, vbabka@...e.cz, roman.gushchin@...ux.dev,
        42.hyeyoo@...il.com, apw@...onical.com, joe@...ches.com,
        dwaipayanray1@...il.com, lukas.bulwahn@...il.com,
        john.johansen@...onical.com, paul@...l-moore.com,
        jmorris@...ei.org, serge@...lyn.com, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
        llvm@...ts.linux.dev, linux-perf-users@...r.kernel.org,
        rcu@...r.kernel.org, linux-security-module@...r.kernel.org,
        tglx@...utronix.de, ravi.bangoria@....com, error27@...il.com,
        luc.vanoostenryck@...il.com
Subject: Re: [PATCH v3 08/57] sched: Simplify wake_up_if_idle()

On Mon, Jun 12, 2023 at 11:07:21AM +0200, Peter Zijlstra wrote:
> Use guards to reduce gotos and simplify control flow.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
>  kernel/sched/core.c  |   20 ++++++--------------
>  kernel/sched/sched.h |   15 +++++++++++++++
>  2 files changed, 21 insertions(+), 14 deletions(-)
> 
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3872,21 +3872,13 @@ static void __ttwu_queue_wakelist(struct
>  void wake_up_if_idle(int cpu)
>  {
>  	struct rq *rq = cpu_rq(cpu);
> -	struct rq_flags rf;
>  
> -	rcu_read_lock();
> -
> -	if (!is_idle_task(rcu_dereference(rq->curr)))
> -		goto out;
> -
> -	rq_lock_irqsave(rq, &rf);
> -	if (is_idle_task(rq->curr))
> -		resched_curr(rq);
> -	/* Else CPU is not idle, do nothing here: */
> -	rq_unlock_irqrestore(rq, &rf);
> -
> -out:
> -	rcu_read_unlock();
> +	guard(rcu)();
> +	if (is_idle_task(rcu_dereference(rq->curr))) {
> +		guard(rq_lock)(rq);

We assume that irq must be disabled when this function called?
Otherwise, I don't understand why this is not

	guard(rq_lock_irqsave)(rq);

?

Regards,
Boqun

> +		if (is_idle_task(rq->curr))
> +			resched_curr(rq);
> +	}
>  }
>  
>  bool cpus_share_cache(int this_cpu, int that_cpu)
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -1678,6 +1678,21 @@ rq_unlock(struct rq *rq, struct rq_flags
>  	raw_spin_rq_unlock(rq);
>  }
>  
> +DEFINE_LOCK_GUARD_1(rq_lock, struct rq,
> +		    rq_lock(_T->lock, &_T->rf),
> +		    rq_unlock(_T->lock, &_T->rf),
> +		    struct rq_flags rf)
> +
> +DEFINE_LOCK_GUARD_1(rq_lock_irq, struct rq,
> +		    rq_lock_irq(_T->lock, &_T->rf),
> +		    rq_unlock_irq(_T->lock, &_T->rf),
> +		    struct rq_flags rf)
> +
> +DEFINE_LOCK_GUARD_1(rq_lock_irqsave, struct rq,
> +		    rq_lock_irqsave(_T->lock, &_T->rf),
> +		    rq_unlock_irqrestore(_T->lock, &_T->rf),
> +		    struct rq_flags rf)
> +
>  static inline struct rq *
>  this_rq_lock_irq(struct rq_flags *rf)
>  	__acquires(rq->lock)
> 
> 

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ