driver core: Avoid deferred probe due to fw_devlink_pause/resume()

With the earlier patch in this series, all devices that deferred probe
due to fw_devlink_pause() will have their probes delayed till the
deferred probe thread is kicked off during late_initcall. This will also
affect all their consumers.

This delayed probing in unnecessary. So this patch just keeps track of
the devices that had their probe deferred due to fw_devlink_pause() and
attempts to probe them once during fw_devlink_resume().

Fixes: 716a7a259690 ("driver core: fw_devlink: Add support for batching fwnode parsing")
Signed-off-by: Saravana Kannan <saravanak@google.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200701194259.3337652-4-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/core.c b/drivers/base/core.c
index d1d2cdc..05d414e 100644 (file)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -50,6 +50,7 @@ static DEFINE_MUTEX(wfs_lock);
 static LIST_HEAD(deferred_sync);
 static unsigned int defer_sync_state_count = 1;
 static unsigned int defer_fw_devlink_count;
+static LIST_HEAD(deferred_fw_devlink);
 static DEFINE_MUTEX(defer_fw_devlink_lock);
 static bool fw_devlink_is_permissive(void);
 
@@ -1244,6 +1245,12 @@ static void fw_devlink_link_device(struct device *dev)
                        fw_ret = -EAGAIN;
        } else {
                fw_ret = -ENODEV;
+               /*
+                * defer_hook is not used to add device to deferred_sync list
+                * until device is bound. Since deferred fw devlink also blocks
+                * probing, same list hook can be used for deferred_fw_devlink.
+                */
+               list_add_tail(&dev->links.defer_hook, &deferred_fw_devlink);
        }
 
        if (fw_ret == -ENODEV)
@@ -1312,6 +1319,9 @@ void fw_devlink_pause(void)
  */
 void fw_devlink_resume(void)
 {
+       struct device *dev, *tmp;
+       LIST_HEAD(probe_list);
+
        mutex_lock(&defer_fw_devlink_lock);
        if (!defer_fw_devlink_count) {
                WARN(true, "Unmatched fw_devlink pause/resume!");
@@ -1323,8 +1333,19 @@ void fw_devlink_resume(void)
                goto out;
 
        device_link_add_missing_supplier_links();
+       list_splice_tail_init(&deferred_fw_devlink, &probe_list);
 out:
        mutex_unlock(&defer_fw_devlink_lock);
+
+       /*
+        * bus_probe_device() can cause new devices to get added and they'll
+        * try to grab defer_fw_devlink_lock. So, this needs to be done outside
+        * the defer_fw_devlink_lock.
+        */
+       list_for_each_entry_safe(dev, tmp, &probe_list, links.defer_hook) {
+               list_del_init(&dev->links.defer_hook);
+               bus_probe_device(dev);
+       }
 }
 /* Device links support end. */
 

diff --git a/include/linux/device.h b/include/linux/device.h
index 9bb2bc7..5efed86 100644 (file)
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -433,7 +433,8 @@ enum dl_dev_state {
  * @suppliers: List of links to supplier devices.
  * @consumers: List of links to consumer devices.
  * @needs_suppliers: Hook to global list of devices waiting for suppliers.
- * @defer_hook: Hook to global list of devices that have deferred sync_state.
+ * @defer_hook: Hook to global list of devices that have deferred sync_state or
+ *             deferred fw_devlink.
  * @need_for_probe: If needs_suppliers is on a list, this indicates if the
  *                 suppliers are needed for probe or not.
  * @status: Driver status information.