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From: Bart Van Assche <bvanassche@acm.org>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: alexander.h.duyck@linux.intel.com,
	Greg KH <gregkh@linuxfoundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	len.brown@intel.com, rafael@kernel.org, linux-pm@vger.kernel.org,
	jiangshanlai@gmail.com, pavel@ucw.cz, zwisler@kernel.org,
	Tejun Heo <tj@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [driver-core PATCH v4 4/6] driver core: Probe devices asynchronously instead of the driver
Date: Thu, 18 Oct 2018 19:31:12 -0700	[thread overview]
Message-ID: <1e061fe5-9be4-77be-5350-4cb7175afdf8@acm.org> (raw)
In-Reply-To: <CAKgT0Ucf-v3FNTA0z=3nPR-xS=0NYeqDjRfDW-KjDE5Ed-n1_g@mail.gmail.com>

On 10/18/18 7:20 PM, Alexander Duyck wrote:
> I see what you are talking about now. Actually I think this was an
> existing issue before my patch even came into play. Basically the code
> as it currently stands is device specific in terms of the attach and
> release code.
> 
> I wonder if we shouldn't have the async_synchronize_full call in
> __device_release_driver moved down and into driver_detach before we
> even start the for loop. Assuming the driver is no longer associated
> with the bus that should flush out all devices so that we can then
> pull them out of the devices list at least. I may look at adding an
> additional bitflag to the device struct to indicate that it has a
> driver attach pending. Then for things like races between any attach
> and detach calls the logic becomes pretty straight forward. Attach
> will set the bit and provide driver data, detach will clear the bit
> and the driver data. If a driver loads in between it should clear the
> bit as well.
> 
> I'll work on it over the next couple days and hopefully have something
> ready for testing/review early next week.

Hi Alex,

How about checking in __driver_attach_async_helper() whether the driver 
pointer is still valid by checking whether bus_for_each_drv(dev->bus, 
...) can still find the driver pointer? That approach requires 
protection with a mutex to avoid races with the driver detach code but 
shouldn't require any new flags in struct device.

Thanks,

Bart.

  reply	other threads:[~2018-10-19  2:31 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-15 15:09 [driver-core PATCH v4 0/6] Add NUMA aware async_schedule calls Alexander Duyck
2018-10-15 15:09 ` [driver-core PATCH v4 1/6] workqueue: Provide queue_work_node to queue work near a given NUMA node Alexander Duyck
2018-10-15 15:09 ` [driver-core PATCH v4 2/6] async: Add support for queueing on specific " Alexander Duyck
2018-10-15 15:09 ` [driver-core PATCH v4 3/6] device core: Consolidate locking and unlocking of parent and device Alexander Duyck
2018-10-18  7:46   ` Rafael J. Wysocki
2018-10-18 17:53   ` Bart Van Assche
2018-10-15 15:09 ` [driver-core PATCH v4 4/6] driver core: Probe devices asynchronously instead of the driver Alexander Duyck
2018-10-18 18:11   ` Bart Van Assche
2018-10-18 19:38     ` Alexander Duyck
2018-10-18 20:13       ` Bart Van Assche
2018-10-19  2:20         ` Alexander Duyck
2018-10-19  2:31           ` Bart Van Assche [this message]
2018-10-19 22:35             ` Alexander Duyck
2018-10-15 15:09 ` [driver-core PATCH v4 5/6] driver core: Attach devices on CPU local to device node Alexander Duyck
2018-10-15 15:09 ` [driver-core PATCH v4 6/6] PM core: Use new async_schedule_dev command Alexander Duyck

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