From: Arnd Bergmann <arnd@arndb•de>
To: Christoph Hellwig <hch@lst•de>
Cc: Arnd Bergmann <arndbergmann@googlemail•com>,
Jonathan Corbet <corbet@lwn•net>,
Frederic Weisbecker <fweisbec@gmail•com>,
LKML <linux-kernel@vger•kernel.org>,
linuxppc-dev@ozlabs•org, John Kacur <jkacur@redhat•com>,
Thomas Gleixner <tglx@linutronix•de>, Ingo Molnar <mingo@elte•hu>,
Alan Cox <alan@lxorguk•ukuu.org.uk>
Subject: Re: [PATCH] macintosh: Explicitly set llseek to no_llseek in ans-lcd
Date: Mon, 16 Nov 2009 13:09:47 +0100 [thread overview]
Message-ID: <200911161309.47186.arnd@arndb.de> (raw)
In-Reply-To: <20091116105427.GA17411@lst.de>
On Monday 16 November 2009, Christoph Hellwig wrote:
> As mentioned before making generic_file_llseek the new default is
> probably a bad idea. The majority of our file_operations instances
> don't actually support seeking, so no_llseek should become the new
> default if you spend some effort on converting things. Anything that
> wants to allow seeking will have to set a llseek method. This also
> mirrors what we do for other file operations. None of the major ones
> has a non-trivial default, it's either silently succeeding for a
> selected few like open or release or returning an error for operatings
> that actually do something like read and write.
Ok, good point.
Do you think we should also prevent pread/pwrite for devices without
an llseek operation, like nonseekable_open does? I guess that would
be consistent.
Then there is the point that (I forgot who) brought up that changing
code to do no_llseek is actually an ABI change. Even if the file
position is never used anywhere, some random user application might
expect a chardev not to return an error when its llseek method is
called, resulting in regressions.
Arnd <><
prev parent reply other threads:[~2009-11-16 12:10 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20091010153314.827301943@linutronix.de>
2009-10-10 15:37 ` [patch 22/28] macintosh: Remove BKL from ans-lcd Thomas Gleixner
2009-10-10 21:14 ` John Kacur
2009-10-10 23:13 ` Alan Cox
2009-10-10 23:27 ` John Kacur
2009-10-11 9:02 ` Benjamin Herrenschmidt
2009-10-21 21:07 ` [PATCH] macintosh: Explicitly set llseek to no_llseek in ans-lcd John Kacur
2009-10-21 21:21 ` Frederic Weisbecker
2009-10-21 21:33 ` John Kacur
2009-10-21 21:45 ` Frederic Weisbecker
2009-10-21 21:53 ` John Kacur
2009-10-21 22:16 ` Frederic Weisbecker
2009-11-02 15:51 ` Arnd Bergmann
2009-11-16 10:54 ` Christoph Hellwig
2009-11-16 12:09 ` Arnd Bergmann [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=200911161309.47186.arnd@arndb.de \
--to=arnd@arndb$(echo .)de \
--cc=alan@lxorguk$(echo .)ukuu.org.uk \
--cc=arndbergmann@googlemail$(echo .)com \
--cc=corbet@lwn$(echo .)net \
--cc=fweisbec@gmail$(echo .)com \
--cc=hch@lst$(echo .)de \
--cc=jkacur@redhat$(echo .)com \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linuxppc-dev@ozlabs$(echo .)org \
--cc=mingo@elte$(echo .)hu \
--cc=tglx@linutronix$(echo .)de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox