Re: [PATCH net-next v2 2/4] driver core: factor sync-state-only link cleanup

[Saravana Kannan]

On Sun, Aug 16, 2026 at 5:00 PM James Hilliard
<james.hilliard1@xxxxxxxxx> wrote:
>
> device_links_driver_bound() drops managed sync-state-only links after a
> consumer successfully probes, then re-evaluates each affected supplier
> for a sync_state() callback.
>
> Frameworks which populate child devices below a driverless device need
> to complete the same lifecycle step, but cannot rely on a successful
> driver probe to trigger it.
>
> Factor the existing cleanup into a lock-held helper and reuse it from
> device_links_driver_bound(). Add a public locking wrapper so frameworks
> which populate children below driverless devices can retire temporary
> fw_devlink proxy links without affecting real dependency or runtime-PM
> links.

See reply to cover letter. I don't think this patch is necessary.

-Saravana

>
> Signed-off-by: James Hilliard <james.hilliard1@xxxxxxxxx>
> ---
>  drivers/base/core.c    | 74 ++++++++++++++++++++++++++++++++++++++------------
>  include/linux/device.h |  1 +
>  2 files changed, 58 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 4d026682944f..627fcfa274f0 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1305,6 +1305,57 @@ static void device_link_drop_managed(struct device_link *link)
>         kref_put(&link->kref, __device_link_del);
>  }
>
> +/* Caller must hold the device links write lock. */
> +static void __device_links_drop_sync_state_only(struct device *dev,
> +                                               struct list_head *sync_list)
> +{
> +       struct device_link *link, *ln;
> +
> +       list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
> +               struct device *supplier;
> +
> +               if (!device_link_test(link, DL_FLAG_MANAGED) ||
> +                   !device_link_test(link, DL_FLAG_SYNC_STATE_ONLY))
> +                       continue;
> +
> +               /*
> +                * DL_FLAG_SYNC_STATE_ONLY excludes all other managed link flags,
> +                * so it is safe to drop the managed link completely.
> +                */
> +               supplier = link->supplier;
> +               device_link_drop_managed(link);
> +
> +               if (defer_sync_state_count)
> +                       __device_links_supplier_defer_sync(supplier);
> +               else
> +                       __device_links_queue_sync_state(supplier, sync_list);
> +       }
> +}
> +
> +/**
> + * device_links_drop_sync_state_only - Drop managed sync-state-only links
> + * @dev: Consumer device whose proxy links should be dropped
> + *
> + * Frameworks which populate child devices below a driverless device can call
> + * this after adding all of the children. The children will have acquired their
> + * own links by then, so the temporary links which only prevent suppliers from
> + * receiving sync_state() callbacks are no longer needed.
> + *
> + * Re-evaluate each affected supplier for a sync_state() callback after its
> + * link is dropped.
> + */
> +void device_links_drop_sync_state_only(struct device *dev)
> +{
> +       LIST_HEAD(sync_list);
> +
> +       device_links_write_lock();
> +       __device_links_drop_sync_state_only(dev, &sync_list);
> +       device_links_write_unlock();
> +
> +       device_links_flush_sync_list(&sync_list, NULL);
> +}
> +EXPORT_SYMBOL_GPL(device_links_drop_sync_state_only);
> +
>  static ssize_t waiting_for_supplier_show(struct device *dev,
>                                          const struct device_attribute *attr,
>                                          char *buf)
> @@ -1418,6 +1469,8 @@ void device_links_driver_bound(struct device *dev)
>         else
>                 __device_links_queue_sync_state(dev, &sync_list);
>
> +       __device_links_drop_sync_state_only(dev, &sync_list);
> +
>         list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
>                 struct device *supplier;
>
> @@ -1425,17 +1478,10 @@ void device_links_driver_bound(struct device *dev)
>                         continue;
>
>                 supplier = link->supplier;
> -               if (device_link_test(link, DL_FLAG_SYNC_STATE_ONLY)) {
> -                       /*
> -                        * When DL_FLAG_SYNC_STATE_ONLY is set, it means no
> -                        * other DL_MANAGED_LINK_FLAGS have been set. So, it's
> -                        * save to drop the managed link completely.
> -                        */
> -                       device_link_drop_managed(link);
> -               } else if (dev_is_best_effort(dev) &&
> -                          device_link_test(link, DL_FLAG_INFERRED) &&
> -                          link->status != DL_STATE_CONSUMER_PROBE &&
> -                          !dev_can_match(link->supplier)) {
> +               if (dev_is_best_effort(dev) &&
> +                   device_link_test(link, DL_FLAG_INFERRED) &&
> +                   link->status != DL_STATE_CONSUMER_PROBE &&
> +                   !dev_can_match(link->supplier)) {
>                         /*
>                          * When dev_is_best_effort() is true, we ignore device
>                          * links to suppliers that don't have a driver.  If the
> @@ -1449,12 +1495,6 @@ void device_links_driver_bound(struct device *dev)
>                         WRITE_ONCE(link->status, DL_STATE_ACTIVE);
>                 }
>
> -               /*
> -                * This needs to be done even for the deleted
> -                * DL_FLAG_SYNC_STATE_ONLY device link in case it was the last
> -                * device link that was preventing the supplier from getting a
> -                * sync_state() call.
> -                */
>                 if (defer_sync_state_count)
>                         __device_links_supplier_defer_sync(supplier);
>                 else
> diff --git a/include/linux/device.h b/include/linux/device.h
> index aee79fd6b32b..8afb9f2b0d82 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -1381,6 +1381,7 @@ struct device_link *device_link_add(struct device *consumer,
>                                     struct device *supplier, u32 flags);
>  void device_link_del(struct device_link *link);
>  void device_link_remove(void *consumer, struct device *supplier);
> +void device_links_drop_sync_state_only(struct device *dev);
>  void device_links_supplier_sync_state_pause(void);
>  void device_links_supplier_sync_state_resume(void);
>  void device_link_wait_removal(void);
>
> --
> 2.53.0
>