linux-kernel - Re: [PATCH 1/2] uio: add warning to documentation

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Date:	Tue, 11 Dec 2012 15:18:16 -0800
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Benedikt Spranger <b.spranger@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, hjk@...sjkoch.de,
	Alexander.Frank@...rspaecher.com
Subject: Re: [PATCH 1/2] uio: add warning to documentation

On Wed, Dec 12, 2012 at 12:12:01AM +0100, Benedikt Spranger wrote:
> The documentation has no clear statement to the POSIX 1003.1 mmap()
> feature, wich allows open(), mmap(), close() while the mmaped pointer is valid.
> The release() hook inveigled driver programmer to activate owermanagement
> functuonality in the release hook. This may harm.
> 
> Signed-off-by: Benedikt Spranger <b.spranger@...utronix.de>
> ---
>  Documentation/DocBook/uio-howto.tmpl |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/DocBook/uio-howto.tmpl b/Documentation/DocBook/uio-howto.tmpl
> index ac3d001..59a886d 100644
> --- a/Documentation/DocBook/uio-howto.tmpl
> +++ b/Documentation/DocBook/uio-howto.tmpl
> @@ -499,8 +499,13 @@ device is actually used.
>  <listitem><para>
>  <varname>int (*release)(struct uio_info *info, struct inode *inode)
>  </varname>: Optional. If you define your own
> -<function>open()</function>, you will probably also want a custom
> +<function>release()</function>, you will probably also want a custom
>  <function>release()</function> function.

That sentance no longer makes sense.

> +</para><para>CAVE: The release hook may be processed, even if a mmap is aktive.

Huh?

> +Disabling clocks or other powermanagement functionality may cause a system
> +crash, hangup or other unwanted sideeffects.
> +</para><para><emphasis>The mmap() function shall add an extra reference to the file associated with the file descriptor fildes which is not removed by a subsequent close() on that file descriptor. This reference shall be removed when there are no more mappings to the file.</emphasis></para><para>
> +<link xlink:href="http://pubs.opengroup.org/onlinepubs/009695399/functions/mmap.html">IEEE Std 1003.1, 2004 Edition, mmap()</link>

It's not up to us to document the mmap system call here, you should know
how to use it if you write a program with it, right?

Sorry, this patch isn't acceptable at all.

greg k-h
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