Re: [RFC PATCH 1/9] ntsync: Introduce the ntsync driver and character device.

From: "Arnd Bergmann" <arnd@arndb.de>
To: "Elizabeth Figura" <zfigura@codeweavers.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org, linux-api@vger.kernel.org
Cc: wine-devel@winehq.org, "André Almeida" <andrealmeid@igalia.com>,
	"Wolfram Sang" <wsa@kernel.org>,
	"Arkadiusz Hiler" <ahiler@codeweavers.com>,
	"Peter Zijlstra" <peterz@infradead.org>
Subject: Re: [RFC PATCH 1/9] ntsync: Introduce the ntsync driver and character device.
Date: Wed, 24 Jan 2024 08:38:52 +0100	[thread overview]
Message-ID: <bd3f6fcb-2239-4fd3-bb9a-c772bbce5a44@app.fastmail.com> (raw)
In-Reply-To: <20240124004028.16826-2-zfigura@codeweavers.com>

On Wed, Jan 24, 2024, at 01:40, Elizabeth Figura wrote:
> ntsync uses a misc device as the simplest and least intrusive uAPI interface.
>
> Each file description on the device represents an isolated NT instance, intended
> to correspond to a single NT virtual machine.
>
> Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>

I'm looking at the ioctl interface to ensure it's well-formed.

Your patches look ok from that perspective, but there are a
few minor things I would check for consistency here:

> +
> +static const struct file_operations ntsync_fops = {
> +	.owner		= THIS_MODULE,
> +	.open		= ntsync_char_open,
> +	.release	= ntsync_char_release,
> +	.unlocked_ioctl	= ntsync_char_ioctl,
> +	.compat_ioctl	= ntsync_char_ioctl,
> +	.llseek		= no_llseek,
> +};

The .compat_ioctl pointer should point to compat_ptr_ioctl()
since the actual ioctl commands all take pointers instead
of interpreting the argument as a number.

On x86 and arm64 this won't make a difference as compat_ptr()
is a nop.

     Arnd