From: Gautham R Shenoy <ego@linux.vnet.ibm.com>
To: "Oliver O'Halloran" <oohall@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH 2/2] cpufreq/powernv: Fix unsafe notifiers
Date: Tue, 25 Feb 2020 12:15:32 +0530 [thread overview]
Message-ID: <20200225064532.GJ12846@in.ibm.com> (raw)
In-Reply-To: <20200206062622.28235-2-oohall@gmail.com>
On Thu, Feb 06, 2020 at 05:26:22PM +1100, Oliver O'Halloran wrote:
> The PowerNV cpufreq driver registers two notifiers: one to catch throttle
> messages from the OCC and one to bump the CPU frequency back to normal
> before a reboot. Both require the cpufreq driver to be registered in order
> to function since the notifier callbacks use various cpufreq_*() functions.
>
> Right now we register both notifiers before we've initialised the driver.
> This seems to work, but we should head off any protential problems by
> registering the notifiers after the driver is initialised.
>
> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
> Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> ---
> drivers/cpufreq/powernv-cpufreq.c | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
> index 1806b1d..03798c4 100644
> --- a/drivers/cpufreq/powernv-cpufreq.c
> +++ b/drivers/cpufreq/powernv-cpufreq.c
> @@ -1114,9 +1114,6 @@ static int __init powernv_cpufreq_init(void)
> if (rc)
> goto out;
>
> - register_reboot_notifier(&powernv_cpufreq_reboot_nb);
> - opal_message_notifier_register(OPAL_MSG_OCC, &powernv_cpufreq_opal_nb);
> -
> if (powernv_pstate_info.wof_enabled)
> powernv_cpufreq_driver.boost_enabled = true;
> else
> @@ -1125,15 +1122,17 @@ static int __init powernv_cpufreq_init(void)
> rc = cpufreq_register_driver(&powernv_cpufreq_driver);
> if (rc) {
> pr_info("Failed to register the cpufreq driver (%d)\n", rc);
> - goto cleanup_notifiers;
> + goto cleanup;
> }
>
> if (powernv_pstate_info.wof_enabled)
> cpufreq_enable_boost_support();
>
> + register_reboot_notifier(&powernv_cpufreq_reboot_nb);
> + opal_message_notifier_register(OPAL_MSG_OCC, &powernv_cpufreq_opal_nb);
> +
> return 0;
> -cleanup_notifiers:
> - unregister_all_notifiers();
> +cleanup:
> clean_chip_info();
> out:
> pr_info("Platform driver disabled. System does not support PState control\n");
> --
> 2.9.5
>
next prev parent reply other threads:[~2020-02-25 6:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-06 6:26 [PATCH 1/2] cpufreq/powernv: Fix use-after-free Oliver O'Halloran
2020-02-06 6:26 ` [PATCH 2/2] cpufreq/powernv: Fix unsafe notifiers Oliver O'Halloran
2020-02-25 6:45 ` Gautham R Shenoy [this message]
2020-02-25 6:42 ` [PATCH 1/2] cpufreq/powernv: Fix use-after-free Gautham R Shenoy
2020-02-25 7:03 ` Andrew Donnellan
2020-02-27 1:31 ` Michael Ellerman
2020-03-17 13:14 ` Michael Ellerman
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