Messages in this thread | | | Date | Fri, 30 Oct 2015 10:06:04 -0700 | From | Stephen Boyd <> | Subject | Re: [PATCH] PM / OPP: Protect updates to list_dev with mutex |
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On 10/30, Viresh Kumar wrote: > dev_opp_list_lock is used everywhere to protect device and OPP lists, > but dev_pm_opp_set_sharing_cpus() is missed somehow. And instead we used > rcu-lock, which wouldn't help here as we are adding a new list_dev. > > This also fixes a problem where we have called kzalloc(..., GFP_KERNEL) > from within rcu-lock, which isn't allowed as kzalloc can sleep when > called with GFP_KERNEL.
Care to share the splat here?
> diff --git a/drivers/base/power/opp/cpu.c b/drivers/base/power/opp/cpu.c > index 7654c5606307..91f15b2e25ee 100644 > --- a/drivers/base/power/opp/cpu.c > +++ b/drivers/base/power/opp/cpu.c > @@ -124,12 +124,12 @@ int dev_pm_opp_set_sharing_cpus(struct device *cpu_dev, cpumask_var_t cpumask) > struct device *dev; > int cpu, ret = 0; > > - rcu_read_lock(); > + mutex_lock(&dev_opp_list_lock); > > dev_opp = _find_device_opp(cpu_dev);
So does _find_device_opp() need to be called with rcu_read_lock() held or not? The comment above the function makes it sound like we need RCU, but we don't do that here anymore.
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