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From: Bart Van Assche <bvanassche@acm.org>
To: Alexander Duyck <alexander.h.duyck@linux.intel.com>,
	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org
Cc: len.brown@intel.com, rafael@kernel.org, linux-pm@vger.kernel.org,
	jiangshanlai@gmail.com, pavel@ucw.cz, zwisler@kernel.org,
	tj@kernel.org, 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 13:13:56 -0700	[thread overview]
Message-ID: <1539893636.81977.29.camel@acm.org> (raw)
In-Reply-To: <e870da1d-48fa-7f2e-6909-b168a06633f2@linux.intel.com>

On Thu, 2018-10-18 at 12:38 -0700, Alexander Duyck wrote:
> Basically if somebody loads a driver the dev->driver becomes set. If a 
> driver is removed it will clear dev->driver and set driver_data to 
> 0/NULL. That is what I am using as a mutex to track it in conjunction 
> with the device mutex. Basically if somebody attempts to attach a driver 
> before we get there we just exit and don't attempt to load this driver.

I don't think that the above matches your code. __device_attach() does not
set the dev->driver pointer before scheduling an asynchronous probe. Only
dev->driver_data gets set before the asynchonous probe is scheduled. Since
driver_detach() only iterates over devices that are in the per-driver klist
it will skip all devices for which an asynchronous probe has been scheduled
but __device_attach_async_helper() has not yet been called. My conclusion
remains that this patch does not prevent a driver pointer to become invalid
concurrently with __device_attach_async_helper() dereferencing the same
driver pointer.

Bart.

  reply	other threads:[~2018-10-18 20:14 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 [this message]
2018-10-19  2:20         ` Alexander Duyck
2018-10-19  2:31           ` Bart Van Assche
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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