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Date:   Thu, 3 Nov 2022 08:47:24 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Luis Chamberlain <mcgrof@kernel.org>
Cc:     Guillermo Rodriguez Garcia <guille.rodriguez@gmail.com>,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Christoph Hellwig <hch@lst.de>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>,
        Kees Cook <keescook@chromium.org>,
        Iurii Zaikin <yzaikin@google.com>
Subject: Re: fs: layered device driver to write to evdev
Message-ID: <20221103074724.GA2685@lst.de>
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On Wed, Nov 02, 2022 at 05:04:11PM -0700, Luis Chamberlain wrote:
> On Wed, Nov 02, 2022 at 02:14:24PM +0100, Guillermo Rodriguez Garcia wrote:
> > I understand that device drivers should implement ->write_iter if they
> > need to be written from kernel space, but evdev does not support this.
> > What is the recommended way to have a layered device driver that can
> > talk to evdev ?
> 
> Shouldn't just writing write_iter support make this work?

Writing to evdev just sound like a lot of troble.  evdev is a tiny
wrapper to expose the in-kernel input API to userspace.  Anything
in-kernel should just directly interact with the input subsystem.