linux-kernel - Re: missing compat-ioctl for CDROM_DRIVE

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Date:	Wed, 29 Jun 2011 14:30:42 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Johannes Stezenbach <js@...21.net>
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: missing compat-ioctl for CDROM_DRIVE_STATUS + FDGETPRM

On Wednesday 29 June 2011, Johannes Stezenbach wrote:
> Sorry for very slow reply.  I think qemu's use of these ioctls
> to probe if the device is a cdrom or floppy is valid, so instead
> of adding a stat() call to check for block device in qemu, I think
> it is better to silence the warning in the kernel.

Well, correct or not, it will keep causing annoying messages on
old kernels, so why not do both?

> Do I get it right that just adding two IGNORE_IOCTL() to
> the ioctl_pointer array in linux/fs/compat_ioctl.c is sufficient,
> like in commit 3f001711?

Yes.

> I.e. these ioctls are handled for block devices earlier
> in compat_sys_ioctl()?

Right. We always first ask the driver, and then search the lookup table
when the driver does not know how to handle it in compat mode.

	Arnd
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