linux-kernel - Re: [PATCH] driver core: Fix device link deferred probe

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Date:   Thu, 02 Nov 2017 22:42:09 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] driver core: Fix device link deferred probe

On Thursday, November 2, 2017 10:22:53 AM CET Adrian Hunter wrote:
> A device probe deferred because of a device link is never probed again
> because it is not added to the deferred_probe_pending_list. Add it, taking
> care of the race with driver_deferred_probe_trigger().
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  drivers/base/dd.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index ad44b40fe284..e4a5bef93344 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -350,6 +350,15 @@ int device_bind_driver(struct device *dev)
>  static atomic_t probe_count = ATOMIC_INIT(0);
>  static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
>  
> +static void driver_deferred_probe_add_trigger(struct device *dev,
> +					      int local_trigger_count)
> +{
> +	driver_deferred_probe_add(dev);
> +	/* Did a trigger occur while probing? Need to re-trigger if yes */
> +	if (local_trigger_count != atomic_read(&deferred_trigger_count))
> +		driver_deferred_probe_trigger();
> +}
> +
>  static int really_probe(struct device *dev, struct device_driver *drv)
>  {
>  	int ret = -EPROBE_DEFER;
> @@ -369,6 +378,8 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>  	}
>  
>  	ret = device_links_check_suppliers(dev);
> +	if (ret == -EPROBE_DEFER)
> +		driver_deferred_probe_add_trigger(dev, local_trigger_count);
>  	if (ret)
>  		return ret;
>  
> @@ -469,10 +480,7 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>  	case -EPROBE_DEFER:
>  		/* Driver requested deferred probing */
>  		dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
> -		driver_deferred_probe_add(dev);
> -		/* Did a trigger occur while probing? Need to re-trigger if yes */
> -		if (local_trigger_count != atomic_read(&deferred_trigger_count))
> -			driver_deferred_probe_trigger();
> +		driver_deferred_probe_add_trigger(dev, local_trigger_count);
>  		break;
>  	case -ENODEV:
>  	case -ENXIO:
> 

Looks OK to me, thanks.

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>