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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Harry van Haaren <harryhaaren@gmail.com>
Cc: "linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Steven Rostedt <rostedt@goodmis.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: CpuFreq Laptop Scaling broken?
Date: Fri, 5 Sep 2014 18:20:30 +0530	[thread overview]
Message-ID: <CAKohpokO6+=5LMr99CVyZYbTHRaUvgkAhHLkgfRaV3LJSfgpkg@mail.gmail.com> (raw)
In-Reply-To: <CAKudYbP09tc8JbBt82pOSy5nfQ42BVv=4knEUhHzz6nbs03SvQ@mail.gmail.com>

On 5 September 2014 17:36, Harry van Haaren <harryhaaren@gmail.com> wrote:
> The down_read_trylock() fails, the other checks are fine.

So my initial guess was correct :)

> If i'm understanding correctly, the cpufreq_rwsem locks the module
> from being unloaded during critical sections while writing to CPU
> speed etc?

Its not about changing speed, but its more of a lock for critical sections
only.. So, yes its required..

> Would that mean that an un-matched pair of down_read() up_write()
> could cause the failure of changing CPU speed?

Probably yes, but why doesn't that happen without rt?

@Steven: Any guesses ?

  reply	other threads:[~2014-09-05 12:50 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-25 12:28 CpuFreq Laptop Scaling broken? Harry van Haaren
2014-08-25 13:55 ` Viresh Kumar
2014-08-25 13:56   ` Viresh Kumar
2014-08-25 16:58     ` Joakim Hernberg
2014-08-25 14:02   ` Harry van Haaren
2014-08-25 17:18     ` Fernando Lopez-Lezcano
2014-08-25 17:36       ` Harry van Haaren
2014-08-26  4:34     ` Viresh Kumar
2014-08-26 22:44       ` Harry van Haaren
2014-08-27 14:53         ` Harry van Haaren
     [not found]           ` <CAKohpokeUufzx7so6FcEd8rAg-MPw+2c9Aug9L_vXdu_4MvNOA@mail.gmail.com>
2014-09-05 12:06             ` Harry van Haaren
2014-09-05 12:50               ` Viresh Kumar [this message]
2014-09-05 22:47                 ` Thomas Gleixner
2014-09-25 12:44                   ` Harry van Haaren
2014-08-25 14:10   ` Steven Rostedt
     [not found]     ` <53FB4EEF.3060809@pavlinux.ru>
2014-08-25 15:03       ` Harry van Haaren

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