From: Stephen Boyd <sboyd@codeaurora.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Rafael Wysocki <rjw@rjwysocki.net>,
mturquette@baylibre.com, linaro-kernel@lists.linaro.org,
linux-pm@vger.kernel.org,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Dan Carpenter <dan.carpenter@oracle.com>,
Dmitry Torokhov <dtor@chromium.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Len Brown <len.brown@intel.com>,
open list <linux-kernel@vger.kernel.org>,
Nishanth Menon <nm@ti.com>, Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH] PM / OPP: Protect updates to list_dev with mutex
Date: Fri, 30 Oct 2015 10:06:04 -0700 [thread overview]
Message-ID: <20151030170604.GD19782@codeaurora.org> (raw)
In-Reply-To: <5f8fac4ad84716ef68fc50ab0b78e11ad2837524.1446205160.git.viresh.kumar@linaro.org>
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.
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2015-10-30 17:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-30 11:56 [PATCH] PM / OPP: Protect updates to list_dev with mutex Viresh Kumar
2015-10-30 12:04 ` Dan Carpenter
2015-10-30 12:40 ` [PATCH] PM / OPP: Propagate error properly from dev_pm_opp_set_sharing_cpus() Viresh Kumar
2015-10-30 20:59 ` Stephen Boyd
2015-10-30 17:06 ` Stephen Boyd [this message]
2015-10-31 2:14 ` [PATCH] PM / OPP: Protect updates to list_dev with mutex Viresh Kumar
2015-11-02 19:14 ` Stephen Boyd
2015-11-04 2:19 ` Viresh Kumar
2015-11-05 8:42 ` Viresh Kumar
2015-11-04 10:22 ` Michael Turquette
2015-11-04 10:25 ` Viresh Kumar
2015-11-04 22:11 ` Stephen Boyd
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