Re: [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during sysfs bind

From: Cornelia Huck <cohuck@redhat.com>
To: Christoph Hellwig <hch@lst.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Kirti Wankhede <kwankhede@nvidia.com>
Cc: Tony Krowiak <akrowiak@linux.ibm.com>,
	Jason Herne <jjherne@linux.ibm.com>,
	kvm@vger.kernel.org, Vasily Gorbik <gor@linux.ibm.com>,
	Jonathan Corbet <corbet@lwn.net>, David Airlie <airlied@linux.ie>,
	linux-s390@vger.kernel.org, Heiko Carstens <hca@linux.ibm.com>,
	linux-doc@vger.kernel.org, dri-devel@lists.freedesktop.org,
	Halil Pasic <pasic@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during sysfs bind
Date: Tue, 15 Jun 2021 16:03:27 +0200	[thread overview]
Message-ID: <87zgvrw7gw.fsf@redhat.com> (raw)
In-Reply-To: <20210615133519.754763-5-hch@lst.de>

On Tue, Jun 15 2021, Christoph Hellwig <hch@lst.de> wrote:

> EPROBE_DEFER is an internal kernel error code and it should not be leaked
> to userspace via the bind_store() sysfs. Userspace doesn't have this
> constant and cannot understand it.
>
> Further, it doesn't really make sense to have userspace trigger a deferred
> probe via bind_store(), which could eventually succeed, while
> simultaneously returning an error back.
>
> Resolve this by splitting driver_probe_device so that the version used
> by the sysfs binding that turns EPROBE_DEFER into -EAGAIN, while the one
> used for internally binding keeps the error code, and calls
> driver_deferred_probe_add where needed.  This also allows to nicely split
> out the defer_all_probes / probe_count checks so that they actually allow
> for full device_{block,unblock}_probing protection while not bothering
> the sysfs bind case.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/base/dd.c | 78 +++++++++++++++++++++++++----------------------
>  1 file changed, 42 insertions(+), 36 deletions(-)
>

Reviewed-by: Cornelia Huck <cohuck@redhat.com>