From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [PATCH] OMAP2 PM: do RCU locking for opp_get_voltage() Date: Tue, 14 Feb 2012 10:48:37 -0800 Message-ID: <87sjid6yka.fsf@ti.com> References: <1329122644-7121-1-git-send-email-arnout@mind.be> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from na3sys009aog102.obsmtp.com ([74.125.149.69]:35336 "EHLO na3sys009aog102.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754994Ab2BNSsm (ORCPT ); Tue, 14 Feb 2012 13:48:42 -0500 Received: by mail-pw0-f45.google.com with SMTP id ro12so741485pbb.32 for ; Tue, 14 Feb 2012 10:48:41 -0800 (PST) In-Reply-To: <1329122644-7121-1-git-send-email-arnout@mind.be> (Arnout Vandecappelle's message of "Mon, 13 Feb 2012 09:44:04 +0100") Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Arnout Vandecappelle (Essensium/Mind)" Cc: linux-omap@vger.kernel.org, Tony Lindgren , Thara Gopinath , Russell King , Philip Oberstaller "Arnout Vandecappelle (Essensium/Mind)" writes: > From: "Arnout Vandecappelle (Essensium/Mind)" > > According to the documentation of opp_get_voltage(), it must be called > with rcu_read_lock() held. The OMAP2 power manager doesn't do this. > The locking error is caught by PROVE_RCU. > > Signed-off-by: Arnout Vandecappelle (Essensium/Mind) Thanks for the patch, I've got a patch from Neil Brown queued for this already: http://marc.info/?l=linux-omap&m=132608991812586&w=2 Kevin > --- > Please CC me, I'm not on the list. > > I was very surprised by this error, because this is the only user of > opp_get_voltage(). > > Regards, > Arnout > --- > arch/arm/mach-omap2/pm.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/arch/arm/mach-omap2/pm.c b/arch/arm/mach-omap2/pm.c > index 00bff46..bce2bdc 100644 > --- a/arch/arm/mach-omap2/pm.c > +++ b/arch/arm/mach-omap2/pm.c > @@ -174,14 +174,17 @@ static int __init omap2_set_init_voltage(char *vdd_name, char *clk_name, > freq = clk->rate; > clk_put(clk); > > + rcu_read_lock(); > opp = opp_find_freq_ceil(dev, &freq); > if (IS_ERR(opp)) { > pr_err("%s: unable to find boot up OPP for vdd_%s\n", > __func__, vdd_name); > + rcu_read_unlock(); > goto exit; > } > > bootup_volt = opp_get_voltage(opp); > + rcu_read_unlock(); > if (!bootup_volt) { > pr_err("%s: unable to find voltage corresponding " > "to the bootup OPP for vdd_%s\n", __func__, vdd_name);