From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-da0-x22f.google.com (mail-da0-x22f.google.com [IPv6:2607:f8b0:400e:c00::22f]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 5B3672C00C4 for ; Tue, 30 Apr 2013 00:07:02 +1000 (EST) Received: by mail-da0-f47.google.com with SMTP id p1so2933877dad.6 for ; Mon, 29 Apr 2013 07:06:57 -0700 (PDT) Date: Mon, 29 Apr 2013 07:06:55 -0700 From: Greg KH To: Ian Munsie Subject: Re: [PATCH] powerpc: Fix missing doorbell IPIs during nap power saving Message-ID: <20130429140655.GA18950@kroah.com> References: <1367223460-4931-1-git-send-email-imunsie@au1.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1367223460-4931-1-git-send-email-imunsie@au1.ibm.com> Cc: Michael Neuling , linuxppc-dev , stable@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, Apr 29, 2013 at 06:17:40PM +1000, Ian Munsie wrote: > From: Ian Munsie > > If a doorbell IPI comes in while a thread is in nap power saving, the > doorbell interrupt won't be replayed by the hardware since it is edge > sensitive. Currently we are not replaying these interrupts in software, > which can cause threads to miss IPIs that come in during power saving > and eventually will result in an RCU warning from rcu_sched that it has > detected a stalled CPU. > > This patch fixes the issue by testing if a doorbell caused the thread to > come out of power saving and sets the corresponding bit in the paca to > indicate a doorbell happened, which will then be handled by the existing > interrupt replay code. > > This is not an issue with other interrupts that can wake a thread > (external, decrementer) as they are level sensitive and will continue to > be asserted by the hardware. > > Signed-off-by: Ian Munsie This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read Documentation/stable_kernel_rules.txt for how to do this properly.