linux-kernel - Re: [RFC PATCH 1/2] driver core: add new dl device status DL_DEV_PROBE

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Date:   Thu, 29 Mar 2018 12:51:21 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Wang Dongsheng <dongsheng.wang@...-semitech.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hanjun Guo <hanjun.guo@...aro.org>,
        Sudeep Holla <sudeep.holla@....com>, yu.zheng@...-semitech.com,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/2] driver core: add new dl device status DL_DEV_PROBE_FAILED

On Thu, Mar 29, 2018 at 12:00 PM, Wang Dongsheng
<dongsheng.wang@...-semitech.com> wrote:
> Currently the initialization state of device is DL_DEV_NO_DRIVER.
> The problem is, after probe failure the state will also be set to
> DL_DEV_NO_DRIVER as well. And the device is not linked, it has no
> supplier or consumer. Thus adding a new state to distinguish
> probe failure and not-probed-yet.
>
> Signed-off-by: Wang Dongsheng <dongsheng.wang@...-semitech.com>

I guess what you want is a cleanup after a failing probe, but after
that the state really is "no driver" again, isn't it?

> ---
>  Documentation/driver-api/device_link.rst |  2 +-
>  drivers/base/base.h                      |  2 +-
>  drivers/base/core.c                      | 22 ++++++++++++++++++++--
>  drivers/base/dd.c                        |  2 +-
>  include/linux/device.h                   |  1 +
>  5 files changed, 24 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/driver-api/device_link.rst b/Documentation/driver-api/device_link.rst
> index 70e328e..9054403 100644
> --- a/Documentation/driver-api/device_link.rst
> +++ b/Documentation/driver-api/device_link.rst
> @@ -247,7 +247,7 @@ State machine
>    :c:func:`device_links_unbind_consumers()`.)
>
>  * If the probe fails, links to suppliers revert back to ``DL_STATE_AVAILABLE``.
> -  (Call to :c:func:`device_links_no_driver()` from :c:func:`really_probe()`.)
> +  (Call to :c:func:`device_links_probe_failed()` from :c:func:`really_probe()`.)
>
>  * If the probe succeeds, links to suppliers progress to ``DL_STATE_ACTIVE``.
>    (Call to :c:func:`device_links_driver_bound()` from :c:func:`driver_bound()`.)
> diff --git a/drivers/base/base.h b/drivers/base/base.h
> index d800de6..f9931d9 100644
> --- a/drivers/base/base.h
> +++ b/drivers/base/base.h
> @@ -158,6 +158,6 @@ extern void device_links_read_unlock(int idx);
>  extern int device_links_check_suppliers(struct device *dev);
>  extern void device_links_driver_bound(struct device *dev);
>  extern void device_links_driver_cleanup(struct device *dev);
> -extern void device_links_no_driver(struct device *dev);
> +extern void device_links_probe_failed(struct device *dev);
>  extern bool device_links_busy(struct device *dev);
>  extern void device_links_unbind_consumers(struct device *dev);
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 5847364..31d4f68 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -452,10 +452,28 @@ static void __device_links_no_driver(struct device *dev)
>         dev->links.status = DL_DEV_NO_DRIVER;
>  }
>
> -void device_links_no_driver(struct device *dev)
> +static void __device_links_probe_failed(struct device *dev)
> +{
> +       struct device_link *link, *ln;
> +
> +       list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers,
> +                                        c_node) {
> +               if (link->flags & DL_FLAG_STATELESS)
> +                       continue;
> +
> +               if (link->flags & DL_FLAG_AUTOREMOVE)
> +                       __device_link_del(link);
> +               else if (link->status != DL_STATE_SUPPLIER_UNBIND)
> +                       WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
> +       }
> +
> +       dev->links.status = DL_DEV_PROBE_FAILED;
> +}
> +
> +void device_links_probe_failed(struct device *dev)
>  {
>         device_links_write_lock();
> -       __device_links_no_driver(dev);
> +       __device_links_probe_failed(dev);
>         device_links_write_unlock();
>  }
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index de6fd09..90d57e0 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -492,7 +492,7 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
>                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
>  pinctrl_bind_failed:
> -       device_links_no_driver(dev);
> +       device_links_probe_failed(dev);
>         devres_release_all(dev);
>         driver_sysfs_remove(dev);
>         dev->driver = NULL;
> diff --git a/include/linux/device.h b/include/linux/device.h
> index b093405..bf9630a 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -794,6 +794,7 @@ struct device_link {
>  enum dl_dev_state {
>         DL_DEV_NO_DRIVER = 0,
>         DL_DEV_PROBING,
> +       DL_DEV_PROBE_FAILED,
>         DL_DEV_DRIVER_BOUND,
>         DL_DEV_UNBINDING,
>  };
> --
> 2.7.4
>
> --
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