From: Jason Gunthorpe <jgg@nvidia.com>
To: Christoph Hellwig <hch@lst.de>
Cc: kvm@vger.kernel.org, linux-doc@vger.kernel.org,
David Airlie <airlied@linux.ie>,
dri-devel@lists.freedesktop.org,
Kirti Wankhede <kwankhede@nvidia.com>,
linux-s390@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Halil Pasic <pasic@linux.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
intel-gfx@lists.freedesktop.org,
Jason Herne <jjherne@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Alex Williamson <alex.williamson@redhat.com>,
Rodrigo Vivi <rodrigo.vivi@intel.com>,
Tony Krowiak <akrowiak@linux.ibm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Cornelia Huck <cohuck@redhat.com>
Subject: Re: [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during sysfs bind
Date: Mon, 14 Jun 2021 19:43:01 -0300 [thread overview]
Message-ID: <20210614224301.GO1002214@nvidia.com> (raw)
In-Reply-To: <20210614150846.4111871-5-hch@lst.de>
On Mon, Jun 14, 2021 at 05:08:40PM +0200, Christoph Hellwig wrote:
> @@ -679,8 +666,6 @@ static int really_probe(struct device *dev, struct device_driver *drv)
> dev->pm_domain->dismiss(dev);
> pm_runtime_reinit(dev);
> dev_pm_set_driver_flags(dev, 0);
> - if (probe_ret == -EPROBE_DEFER)
> - driver_deferred_probe_add_trigger(dev, local_trigger_count);
> done:
I like the new arrangement - however I'm looking at the ordering
relative to this:
> atomic_dec(&probe_count);
> wake_up_all(&probe_waitqueue);
And wondering if the idea is that driver_deferred_probe_add_trigger()
is supposed to be enclosed by the atomic, so that the
device_block_probing() / wait_for_device_probe() sequence is actually
a fence against queuing new work?
Which is suggesting that the other driver_deferred_probe_add_trigger()
at the top of really_probe is already ordered wrong?
Although, if that is the idea the wait_for_device_probe() doesn't look
entirely sequenced right..
It looks easy enough to fix by moving the probe_count up:
> +static int driver_probe_device(struct device_driver *drv, struct device *dev)
> +{
> + int trigger_count = atomic_read(&deferred_trigger_count);
> + int ret;
> +
> + ret = __driver_probe_device(drv, dev);
> + if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
> + driver_deferred_probe_add(dev);
> +
> + /*
> + * Did a trigger occur while probing? Need to re-trigger if yes
> + */
> + if (trigger_count != atomic_read(&deferred_trigger_count) &&
> + !defer_all_probes)
> + driver_deferred_probe_trigger();
> + }
into here?
I didn't see a reason why it couldn't enclose the pm stuff too..
Jason
next parent reply other threads:[~2021-06-14 22:43 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210614150846.4111871-1-hch@lst.de>
[not found] ` <20210614150846.4111871-5-hch@lst.de>
2021-06-14 22:43 ` Jason Gunthorpe [this message]
[not found] ` <20210614150846.4111871-2-hch@lst.de>
2021-06-15 5:16 ` [PATCH 01/10] driver core: Pull required checks into driver_probe_device() Greg Kroah-Hartman
2021-06-15 10:27 ` Cornelia Huck
[not found] ` <20210614150846.4111871-3-hch@lst.de>
2021-06-14 18:47 ` [PATCH 02/10] driver core: Better distinguish probe errors in really_probe Kirti Wankhede
2021-06-15 5:17 ` Greg Kroah-Hartman
2021-06-15 5:21 ` Allow mdev drivers to directly create the vfio_device (v2 / alternative) Greg Kroah-Hartman
[not found] ` <20210615055021.GB21080@lst.de>
2021-06-15 15:27 ` Jason Gunthorpe
[not found] ` <20210614150846.4111871-4-hch@lst.de>
2021-06-15 5:18 ` [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind Greg Kroah-Hartman
2021-06-15 10:31 ` Cornelia Huck
[not found] ` <20210614150846.4111871-6-hch@lst.de>
2021-06-15 5:20 ` [PATCH 05/10] driver core: Export device_driver_attach() Greg Kroah-Hartman
2021-06-15 10:49 ` Cornelia Huck
[not found] ` <20210614150846.4111871-7-hch@lst.de>
2021-06-15 10:50 ` [PATCH 06/10] vfio/mdev: Remove CONFIG_VFIO_MDEV_DEVICE Cornelia Huck
[not found] ` <20210614150846.4111871-8-hch@lst.de>
2021-06-15 10:54 ` [PATCH 07/10] vfio/mdev: Allow the mdev_parent_ops to specify the device driver to bind Cornelia Huck
[not found] <20210615133519.754763-1-hch@lst.de>
[not found] ` <20210615133519.754763-5-hch@lst.de>
2021-06-15 14:03 ` [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during sysfs bind Cornelia Huck
2021-06-15 19:36 ` Alex Williamson
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