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From: Ming Lei <tom.leiming@gmail.com>
To: Samu Onkalo <samu.p.onkalo@nokia.com>
Cc: gregkh@suse.de, hmh@hmh.eng.br, alan@linux.intel.com,
	akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] device-core: sysfs open - close notify
Date: Mon, 1 Nov 2010 00:14:04 +0800	[thread overview]
Message-ID: <AANLkTikRSF-4o=Jnyg2_Wa4gg7E+s_tM9ZD3g+f7hyWm@mail.gmail.com> (raw)
In-Reply-To: <1288529170-28890-1-git-send-email-samu.p.onkalo@nokia.com>

2010/10/31 Samu Onkalo <samu.p.onkalo@nokia.com>:
> Device drivers have no idea when somebody in userspace keeps some sysfs entry
> open. The driver just received read or write calls. The driver may want to
> control HW state based on activity so it either have to turn HW on and off
> for each sysfs access or it needs separate enable disable entry which controls
> the HW state. In cases where sysfs is used to pass some events under interrupt
> control (like proximity events from the proximity sensors) it is not enough to
> just keep sysfs entry open in userspace.

Since very few drivers have this kind of requirement, why not take notifier
call chain mechanism to do such thing? eg. register a notifier function
if the driver is interested in such kind of open/close events.

Your patch may cause many unnecessary memory waste because
most of drivers does not need attribute file .open/.close notifier.


thanks,
-- 
Lei Ming

  reply	other threads:[~2010-10-31 16:14 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-31 12:46 [RFC PATCH] device-core: sysfs open - close notify Samu Onkalo
2010-10-31 16:14 ` Ming Lei [this message]
2010-11-01 17:11   ` Alan Cox
2010-11-02  6:30     ` Onkalo Samu
2010-11-16  3:14       ` Enrico Weigelt

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