Messages in this thread | | | Date | Wed, 21 Nov 2012 13:46:21 +0000 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH] PM / devfreq: missing rcu_read_lock() added for find_device_opp() |
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Quoting MyungJoo Ham (myungjoo.ham@samsung.com): > opp_get_notifier() uses find_device_opp(), which requires to > held rcu_read_lock. In order to keep the notifier-header > valid, we have added rcu_read_lock(). > > Reported-by: Kees Cook <keescook@chromium.org> > Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com> > --- > drivers/devfreq/devfreq.c | 26 ++++++++++++++++++++------ > 1 files changed, 20 insertions(+), 6 deletions(-) > > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c > index 45e053e..e91cb22 100644 > --- a/drivers/devfreq/devfreq.c > +++ b/drivers/devfreq/devfreq.c > @@ -1023,11 +1023,18 @@ struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq, > */ > int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq) > { > - struct srcu_notifier_head *nh = opp_get_notifier(dev); > + struct srcu_notifier_head *nh; > + int ret = 0; > > + rcu_read_lock(); > + nh = opp_get_notifier(dev); > if (IS_ERR(nh)) > - return PTR_ERR(nh); > - return srcu_notifier_chain_register(nh, &devfreq->nb); > + ret = PTR_ERR(nh); > + if (!ret) > + ret = srcu_notifier_chain_register(nh, &devfreq->nb);
Hm, but if I'm seeing right, srcu_notifier_chain_register calls mutex_lock(), which sleeps, so you can't do that under rcu_read_lock().
-serge
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