From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Boyd Subject: Re: [PATCH V2 2/8] PM / OPP: Don't use OPP structure outside of rcu protected section Date: Mon, 24 Oct 2016 15:52:38 -0700 Message-ID: <20161024225238.GR26139@codeaurora.org> References: <7a0754e64236db2a977c6a6402c222fea6dc866d.1476952750.git.viresh.kumar@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <7a0754e64236db2a977c6a6402c222fea6dc866d.1476952750.git.viresh.kumar@linaro.org> Sender: linux-kernel-owner@vger.kernel.org To: Viresh Kumar Cc: Rafael Wysocki , nm@ti.com, Viresh Kumar , linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Vincent Guittot , robh@kernel.org, d-gerlach@ti.com, broonie@kernel.org List-Id: linux-pm@vger.kernel.org On 10/20, Viresh Kumar wrote: > The OPP structure must not be used out of the rcu protected section. > Cache the values to be used in separate variables instead. > > Signed-off-by: Viresh Kumar Was this found by visual inspection or through some static checker? Just curious. > @@ -633,6 +634,14 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) > return ret; > } > > + if (IS_ERR(old_opp)) { > + old_u_volt = 0; > + } else { > + old_u_volt = old_opp->u_volt; > + old_u_volt_min = old_opp->u_volt_min; > + old_u_volt_max = old_opp->u_volt_max; > + } > + > u_volt = opp->u_volt; > u_volt_min = opp->u_volt_min; > u_volt_max = opp->u_volt_max; > @@ -677,9 +686,10 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) > __func__, old_freq); > restore_voltage: > /* This shouldn't harm even if the voltages weren't updated earlier */ > - if (!IS_ERR(old_opp)) > - _set_opp_voltage(dev, reg, old_opp->u_volt, > - old_opp->u_volt_min, old_opp->u_volt_max); > + if (old_u_volt) { What if old_u_volt == 0 is valid? We could have another variable like 'valid' or something that we use to figure out if we should set values instead. Then this isn't a potential pitfall. > + _set_opp_voltage(dev, reg, old_u_volt, old_u_volt_min, > + old_u_volt_max); > + } > > return ret; > } -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project