From: Matthias Kaehlcke <mka@chromium.org>
To: Chanwoo Choi <cw00.choi@samsung.com>
Cc: MyungJoo Ham <myungjoo.ham@samsung.com>,
Kyungmin Park <kyungmin.park@samsung.com>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
Brian Norris <briannorris@chromium.org>,
Douglas Anderson <dianders@chromium.org>,
Enric Balletbo i Serra <enric.balletbo@collabora.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Viresh Kumar <viresh.kumar@linaro.org>,
Lee Jones <lee.jones@linaro.org>,
Benson Leung <bleung@chromium.org>,
Olof Johansson <olof@lixom.net>
Subject: Re: [PATCH v5 07/12] PM / devfreq: export devfreq_class
Date: Fri, 6 Jul 2018 11:09:23 -0700 [thread overview]
Message-ID: <20180706180923.GH129942@google.com> (raw)
In-Reply-To: <5B3C5B78.6020401@samsung.com>
Hi,
On Wed, Jul 04, 2018 at 02:30:32PM +0900, Chanwoo Choi wrote:
> I didn't see any framework which exporting the class instance.
> It is very dangerous. Unknown device drivers is able to reset
> the 'devfreq_class' instance. I can't agree this approach.
While I agree that it is potential dangerous it is actually a common
practice to export the class:
grep "extern struct class " include/linux/ -R
include/linux/rio.h:extern struct class rio_mport_class;
include/linux/tty.h:extern struct class *tty_class;
include/linux/fb.h:extern struct class *fb_class;
include/linux/ide.h:extern struct class *ide_port_class;
include/linux/device.h:extern struct class * __must_check __class_create(struct module *owner,
include/linux/devfreq.h:extern struct class *devfreq_class;
include/linux/switchtec.h:extern struct class *switchtec_class;
include/linux/input.h:extern struct class input_class;
include/linux/genhd.h:extern struct class block_class;
include/linux/power_supply.h:extern struct class *power_supply_class;
include/linux/rtc.h:extern struct class *rtc_class;
struct class_interface and class_interface_register() would be
pointless without exported classes.
My understanding is that the kernel is often lax on encapsulation and
exposes private/delicate data pragmatically within the kernel when
needed because "the kernel trusts itself".
Thanks
Matthias
next prev parent reply other threads:[~2018-07-06 18:09 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-03 23:46 [PATCH v5 00/12] Add throttler driver for non-thermal throttling Matthias Kaehlcke
2018-07-03 23:46 ` [PATCH v5 01/12] PM / devfreq: Init user limits from OPP limits, not viceversa Matthias Kaehlcke
2018-07-03 23:46 ` [PATCH v5 02/12] PM / devfreq: Fix handling of min/max_freq == 0 Matthias Kaehlcke
2018-07-04 2:20 ` Chanwoo Choi
2018-07-06 16:36 ` Matthias Kaehlcke
2018-07-12 8:34 ` Chanwoo Choi
2018-07-03 23:46 ` [PATCH v5 03/12] PM / devfreq: Don't adjust to user limits in governors Matthias Kaehlcke
2018-07-04 2:27 ` Chanwoo Choi
2018-08-02 23:36 ` Matthias Kaehlcke
2018-08-03 0:03 ` Chanwoo Choi
2018-08-03 0:24 ` Matthias Kaehlcke
2018-08-03 0:43 ` Chanwoo Choi
2018-07-03 23:46 ` [PATCH v5 04/12] PM / devfreq: Add struct devfreq_policy Matthias Kaehlcke
2018-07-04 2:51 ` Chanwoo Choi
2018-07-06 17:07 ` Matthias Kaehlcke
2018-07-12 8:38 ` Chanwoo Choi
2018-08-03 0:04 ` Chanwoo Choi
2018-07-03 23:46 ` [PATCH v5 05/12] PM / devfreq: Add support for policy notifiers Matthias Kaehlcke
2018-07-04 6:41 ` Chanwoo Choi
2018-07-06 17:53 ` Matthias Kaehlcke
2018-07-12 8:44 ` Chanwoo Choi
2018-07-16 17:50 ` Matthias Kaehlcke
2018-07-31 19:39 ` Matthias Kaehlcke
2018-08-01 1:22 ` Chanwoo Choi
2018-08-01 17:08 ` Matthias Kaehlcke
2018-08-02 1:58 ` Chanwoo Choi
2018-08-02 23:13 ` Matthias Kaehlcke
2018-08-02 23:48 ` Matthias Kaehlcke
2018-08-03 0:14 ` Chanwoo Choi
2018-08-06 19:21 ` Matthias Kaehlcke
2018-08-06 22:31 ` Chanwoo Choi
2018-08-06 22:50 ` Chanwoo Choi
2018-08-07 0:23 ` Matthias Kaehlcke
2018-08-07 1:35 ` Chanwoo Choi
2018-08-07 22:34 ` Matthias Kaehlcke
2018-08-02 23:56 ` Chanwoo Choi
2018-08-06 18:46 ` Matthias Kaehlcke
2018-08-06 22:16 ` Chanwoo Choi
2018-07-03 23:46 ` [PATCH v5 06/12] PM / devfreq: Make update_devfreq() public Matthias Kaehlcke
2018-08-01 8:32 ` Chanwoo Choi
2018-07-03 23:47 ` [PATCH v5 07/12] PM / devfreq: export devfreq_class Matthias Kaehlcke
2018-07-04 5:30 ` Chanwoo Choi
2018-07-06 18:09 ` Matthias Kaehlcke [this message]
2018-07-12 9:08 ` Chanwoo Choi
2018-07-16 19:41 ` Matthias Kaehlcke
2018-07-31 19:29 ` Matthias Kaehlcke
2018-08-01 8:18 ` Chanwoo Choi
2018-08-01 17:18 ` Matthias Kaehlcke
2018-07-03 23:47 ` [PATCH v5 08/12] cpufreq: Add stub for cpufreq_update_policy() Matthias Kaehlcke
2018-07-04 10:41 ` Rafael J. Wysocki
2018-07-10 22:24 ` Matthias Kaehlcke
2018-07-04 10:44 ` Viresh Kumar
2018-07-03 23:47 ` [PATCH v5 09/12] dt-bindings: misc: add bindings for throttler Matthias Kaehlcke
2018-07-04 10:00 ` Viresh Kumar
2018-08-01 8:27 ` Chanwoo Choi
2018-08-01 17:39 ` Matthias Kaehlcke
2018-07-03 23:47 ` [PATCH v5 10/12] misc: throttler: Add core support for non-thermal throttling Matthias Kaehlcke
2018-07-03 23:47 ` [PATCH v5 11/12] misc: throttler: Add Chrome OS EC throttler Matthias Kaehlcke
2018-07-03 23:47 ` [PATCH v5 12/12] mfd: cros_ec: Add throttler sub-device Matthias Kaehlcke
2018-07-04 7:59 ` Lee Jones
[not found] ` <CGME20180703234727epcas3p1b9f4a41b1f1714c8c059100d46b816dd@epcms1p5>
2018-07-04 2:24 ` [PATCH v5 01/12] PM / devfreq: Init user limits from OPP limits, not viceversa MyungJoo Ham
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