From: Viresh Kumar <viresh.kumar@linaro.org>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux PM list <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/12] cpufreq: governor: Close dbs_data update race condition
Date: Fri, 19 Feb 2016 07:57:21 +0530 [thread overview]
Message-ID: <20160219022721.GA16983@vireshk-i7> (raw)
In-Reply-To: <CAJZ5v0jFP5hdcomAw1GcMgVAhw1mnwpZ3vdM7vN59SFkiug_YA@mail.gmail.com>
On 18-02-16, 17:20, Rafael J. Wysocki wrote:
> On Thu, Feb 18, 2016 at 6:24 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > On 18-02-16, 02:19, Rafael J. Wysocki wrote:
> >> @@ -112,7 +112,7 @@ static ssize_t governor_store(struct kob
> >>
> >> mutex_lock(&dbs_data->mutex);
> >>
> >> - if (gattr->store)
> >> + if (dbs_data->usage_count && gattr->store)
> >
> > That's not gonna be enough. The above lock doesn't guarantee
> > protection with any such races.
Oops, I completely misread it. Really sorry about that.
But now that I have read the code again, I wonder why we need this protection at
all. The first thing we do after decrementing the usage_count counter, is we put
the kobject. Which will ensure that the sysfs files are all gone. So, what is
the race we are trying to fix then?
> Yeah, they are quite useless. But not in this patch.
Sure.
--
viresh
next prev parent reply other threads:[~2016-02-19 2:27 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-18 1:17 [PATCH 0/12] cpufreq: More governor code reorganization Rafael J. Wysocki
2016-02-18 1:19 ` [PATCH 1/12] cpufreq: governor: Close dbs_data update race condition Rafael J. Wysocki
2016-02-18 5:24 ` Viresh Kumar
2016-02-18 16:20 ` Rafael J. Wysocki
2016-02-19 2:27 ` Viresh Kumar [this message]
2016-02-19 2:34 ` Rafael J. Wysocki
2016-02-19 3:09 ` Viresh Kumar
2016-02-18 1:20 ` [PATCH 2/12] cpufreq: governor: Move io_is_busy to struct dbs_data Rafael J. Wysocki
2016-02-18 5:28 ` Viresh Kumar
2016-02-18 1:21 ` [PATCH 3/12] cpufreq: governor: Add a ->start callback for governors Rafael J. Wysocki
2016-02-18 5:36 ` Viresh Kumar
2016-02-18 1:22 ` [PATCH 4/12] cpufreq: governor: Drop unused governor callback and data fields Rafael J. Wysocki
2016-02-18 5:37 ` Viresh Kumar
2016-02-18 1:24 ` [PATCH 5/12] cpufreq: ondemand: Drop one more callback from struct od_ops Rafael J. Wysocki
2016-02-18 5:38 ` Viresh Kumar
2016-02-18 1:26 ` [PATCH 6/12] cpufreq: governor: Fix CPU load information updates via ->store Rafael J. Wysocki
2016-02-18 5:44 ` Viresh Kumar
2016-02-18 17:37 ` Rafael J. Wysocki
2016-02-18 1:28 ` [PATCH 7/12] cpufreq: ondemand: Rework the handling of powersave bias updates Rafael J. Wysocki
2016-02-18 5:53 ` Viresh Kumar
2016-02-18 1:30 ` [PATCH 8/12] cpufreq: governor: Make governor private data per-policy Rafael J. Wysocki
2016-02-18 6:03 ` Viresh Kumar
2016-02-18 17:56 ` [PATCH v2 " Rafael J. Wysocki
2016-02-19 2:36 ` Viresh Kumar
2016-02-18 1:31 ` [PATCH 9/12] cpufreq: governor: Move per-CPU data to the common code Rafael J. Wysocki
2016-02-18 6:08 ` Viresh Kumar
2016-02-18 1:32 ` [PATCH 10/12] cpufreq: governor: Relocate definitions of tuners structures Rafael J. Wysocki
2016-02-18 6:09 ` Viresh Kumar
2016-02-18 17:57 ` [PATCH v2 " Rafael J. Wysocki
2016-02-19 2:36 ` Viresh Kumar
2016-02-18 1:33 ` [PATCH 11/12] cpufreq: governor: Make dbs_data_mutex static Rafael J. Wysocki
2016-02-18 6:09 ` Viresh Kumar
2016-02-18 1:38 ` [PATCH 12/12] cpufreq: governor: Narrow down the dbs_data_mutex coverage Rafael J. Wysocki
2016-02-18 6:20 ` Viresh Kumar
2016-02-18 16:32 ` Rafael J. Wysocki
2016-02-18 17:58 ` [PATCH v2 " Rafael J. Wysocki
2016-02-19 2:38 ` Viresh Kumar
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