linux-kernel - Re: [PATCH tip/core/rcu 7/9] arm64: Use common outgoing-CPU-notification code

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: <20150521124833.GJ6776@linux.vnet.ibm.com>
Date:	Thu, 21 May 2015 05:48:33 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Will Deacon <will.deacon@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...nel.org" <mingo@...nel.org>,
	"laijs@...fujitsu.com" <laijs@...fujitsu.com>,
	"dipankar@...ibm.com" <dipankar@...ibm.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"mathieu.desnoyers@...icios.com" <mathieu.desnoyers@...icios.com>,
	"josh@...htriplett.org" <josh@...htriplett.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"peterz@...radead.org" <peterz@...radead.org>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>,
	"dhowells@...hat.com" <dhowells@...hat.com>,
	"edumazet@...gle.com" <edumazet@...gle.com>,
	"dvhart@...ux.intel.com" <dvhart@...ux.intel.com>,
	"fweisbec@...il.com" <fweisbec@...il.com>,
	"oleg@...hat.com" <oleg@...hat.com>,
	"bobby.prani@...il.com" <bobby.prani@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Catalin Marinas <Catalin.Marinas@....com>
Subject: Re: [PATCH tip/core/rcu 7/9] arm64: Use common
 outgoing-CPU-notification code

On Thu, May 21, 2015 at 09:58:06AM +0100, Will Deacon wrote:
> Hi Paul,
> 
> Sorry for being late on this one.

No problem!  In fact, just in time -- I was going to bug you about
this later today.  ;-)

> On Tue, May 12, 2015 at 10:50:05PM +0100, Paul E. McKenney wrote:
> > From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
> > 
> > This commit removes the open-coded CPU-offline notification with new
> > common code.  In particular, this change avoids calling scheduler code
> > using RCU from an offline CPU that RCU is ignoring.  This is a minimal
> > change.  A more intrusive change might invoke the cpu_check_up_prepare()
> > and cpu_set_state_online() functions at CPU-online time, which would
> > allow onlining throw an error if the CPU did not go offline properly.
> > 
> > Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> > Cc: linux-arm-kernel@...ts.infradead.org
> > Cc: Catalin Marinas <catalin.marinas@....com>
> > Cc: Will Deacon <will.deacon@....com>
> > ---
> >  arch/arm64/kernel/smp.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> I don't have a better idea, so:
> 
>   Acked-by: Will Deacon <will.deacon@....com>
> 
> Is this queued via -tip already, or can we pick it into the arm64 tree
> for 4.2?

Feel free to take it into the arm64 tree.  Just let me know, and I
will drop it from my tree.

Now I only need to bug the arm32 guys.  ;-)

							Thanx, Paul

> Cheers,
> 
> Will
> 
> > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> > index 2cb008177252..a899c1beff54 100644
> > --- a/arch/arm64/kernel/smp.c
> > +++ b/arch/arm64/kernel/smp.c
> > @@ -253,15 +253,13 @@ static int op_cpu_kill(unsigned int cpu)
> >  	return cpu_ops[cpu]->cpu_kill(cpu);
> >  }
> >  
> > -static DECLARE_COMPLETION(cpu_died);
> > -
> >  /*
> >   * called on the thread which is asking for a CPU to be shutdown -
> >   * waits until shutdown has completed, or it is timed out.
> >   */
> >  void __cpu_die(unsigned int cpu)
> >  {
> > -	if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
> > +	if (!cpu_wait_death(cpu, 5)) {
> >  		pr_crit("CPU%u: cpu didn't die\n", cpu);
> >  		return;
> >  	}
> > @@ -294,7 +292,7 @@ void cpu_die(void)
> >  	local_irq_disable();
> >  
> >  	/* Tell __cpu_die() that this CPU is now safe to dispose of */
> > -	complete(&cpu_died);
> > +	(void)cpu_report_death();
> >  
> >  	/*
> >  	 * Actually shutdown the CPU. This must never fail. The specific hotplug
> > -- 
> > 1.8.1.5
> > 
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/