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Date: Fri, 24 Jan 2014 16:19:36 -0800
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-rt-users <linux-rt-users@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
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        Joakim Hernberg <jbh@alchemy.lu>, Joe Korty <joe.korty@ccur.com>,
        Muli Baron <muli.baron@gmail.com>
Subject: Re: [PATCH RT v2] timer: Raise softirq if there's irq_work
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On Fri, Jan 24, 2014 at 03:35:42PM -0500, Steven Rostedt wrote:
> On Fri, 24 Jan 2014 21:20:39 +0100
> Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:
> 
> > * Steven Rostedt | 2014-01-24 15:09:33 [-0500]:
> > 
> > >[ Talking with Sebastian on IRC, it seems that doing the irq_work_run()
> > >  from the interrupt in -rt is a bad thing. Here we simply raise the
> > >  softirq if there's irq work to do. This too boots on my i7 ]
> > 
> > It is okay in general because most of the users should not run in bare
> > interrupt context. The only exception here is the nohz_full_kick_work
> > thing.
> 
> I know we discussed this on IRC, but I wanted to publicly state that
> the missing irq work callback was the RCU's rsp_wakeup() function.

Failing to invoke rsp_wakeup() when it was needed could potentially
stop RCU grace periods from happening, so having rsp_wakeup() happen
when it is needed is pretty important...

But I would guess that you knew that already.  ;-)

							Thanx, Paul