linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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 11:11:15 -0700	[thread overview]
Message-ID: <1539886275.81977.17.camel@acm.org> (raw)
In-Reply-To: <20181015150926.29520.45280.stgit@localhost.localdomain>

On Mon, 2018-10-15 at 08:09 -0700, Alexander Duyck wrote:
> +static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
> +{
> +	struct device *dev = _dev;
> +
> +	__device_driver_lock(dev, dev->parent);
> +
> +	/*
> +	 * If someone attempted to bind a driver either successfully or
> +	 * unsuccessfully before we got here we should just skip the driver
> +	 * probe call.
> +	 */
> +	if (!dev->driver) {
> +		struct device_driver *drv = dev_get_drvdata(dev);
> +
> +		if (drv)
> +			driver_probe_device(drv, dev);
> +	}
> +
> +	__device_driver_unlock(dev, dev->parent);
> +
> +	put_device(dev);
> +
> +	dev_dbg(dev, "async probe completed\n");
> +}
> +
>  static int __driver_attach(struct device *dev, void *data)
>  {
>  	struct device_driver *drv = data;
> @@ -945,6 +971,25 @@ static int __driver_attach(struct device *dev, void *data)
>  		return ret;
>  	} /* ret > 0 means positive match */
>  
> +	if (driver_allows_async_probing(drv)) {
> +		/*
> +		 * Instead of probing the device synchronously we will
> +		 * probe it asynchronously to allow for more parallelism.
> +		 *
> +		 * We only take the device lock here in order to guarantee
> +		 * that the dev->driver and driver_data fields are protected
> +		 */
> +		dev_dbg(dev, "scheduling asynchronous probe\n");
> +		device_lock(dev);
> +		if (!dev->driver) {
> +			get_device(dev);
> +			dev_set_drvdata(dev, drv);
> +			async_schedule(__driver_attach_async_helper, dev);
> +		}
> +		device_unlock(dev);
> +		return 0;
> +	}
> +
>  	device_driver_attach(drv, dev);

What prevents that the driver pointer becomes invalid after async_schedule() has
been called and before __driver_attach_async_helper() is called? I think we need
protection against concurrent driver_unregister() and __driver_attach_async_helper()
calls. I'm not sure whether that is possible without introducing a new mutex.

Thanks,

Bart.


  reply	other threads:[~2018-10-18 18:11 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 [this message]
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
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1539886275.81977.17.camel@acm.org \
    --to=bvanassche@acm.org \
    --cc=akpm@linux-foundation.org \
    --cc=alexander.h.duyck@linux.intel.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=jiangshanlai@gmail.com \
    --cc=len.brown@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=pavel@ucw.cz \
    --cc=rafael@kernel.org \
    --cc=tj@kernel.org \
    --cc=zwisler@kernel.org \
    --subject='Re: [driver-core PATCH v4 4/6] driver core: Probe devices asynchronously instead of the driver' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).