linux-kernel - Re: [PATCH] kernfs: remove outdated and confusing comment

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Message-ID: <20150311131554.GA10067@katana>
Date:	Wed, 11 Mar 2015 14:15:54 +0100
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Tejun Heo <tj@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linux-sh@...r.kernel.org
Subject: Re: [PATCH] kernfs: remove outdated and confusing comment

> Hmm... poll isn't hooked up for bin files and the behavior isn't well

Ah, thanks! I assumed something like that but could not find the
relevant code.

> defined either.  The open file's event counter is never synchronized
> to the backing node's.  Before the first kernfs_notify(), it won't
> trigger and after always.  We'll prolly need to define that better.
> What's the use case that you're interested in?

I wanted to add notification to drivers/i2c/i2c-slave-eeprom.c which is
a software backend when the Linux system is acting as an I2C slave
device.  This is basically a dual mem driver. One side is exposed to the
system as a bin-file in sysfs. The other side is accessible like an
EEPROM for other I2C masters connected to the bus. The notification
should report to userspace when a remote master has written something
to us so the memory contents changed.

I know this is not the best way of notification because we don't know
what changed and would need to compare. However, the whole I2C slave
framework is still very young and I wanted to play with it for the case
where only a few bytes are exposed.

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