linux-kernel - [PATCH v2 01/17] Revert "driver core: Avoid deferred probe due to fw_devlink

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Date:   Fri, 20 Nov 2020 18:02:16 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Saravana Kannan <saravanak@...gle.com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        kernel-team@...roid.com, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: [PATCH v2 01/17] Revert "driver core: Avoid deferred probe due to fw_devlink_pause/resume()"

This reverts commit 2451e746478a6a6e981cfa66b62b791ca93b90c8.

fw_devlink_pause/resume() was an incomplete attempt at boot time
optimization. That's going to get replaced by a much better optimization
at the end of the series. Since fw_devlink_pause/resume() is going away,
changes made for that can also go away.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
 drivers/base/core.c    | 21 ---------------------
 include/linux/device.h |  3 +--
 2 files changed, 1 insertion(+), 23 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index d661ada1518f..b202fe54f46a 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -51,7 +51,6 @@ 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);
 
@@ -1470,12 +1469,6 @@ 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)
@@ -1544,9 +1537,6 @@ 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!");
@@ -1558,19 +1548,8 @@ 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 5ed101be7b2e..da00f8e449bb 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -352,8 +352,7 @@ 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 or
- *		deferred fw_devlink.
+ * @defer_hook: Hook to global list of devices that have deferred sync_state.
  * @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.
-- 
2.29.2.454.gaff20da3a2-goog