[RFT PATCH v3 1/1] usb: hub: Fix flushing of delayed work used for post resume purposes

[Mathias Nyman <mathias.nyman@linux.intel.com>]

Delayed work that prevents USB3 hubs from runtime-suspending too early
needed to be flushed in hub_quiesce() to resolve issues detected on
QC SC8280XP CRD board during suspend resume testing.

This flushing did however trigger new issues on Raspberry Pi 3B+, which
doesn't have USB3 ports, and doesn't queue any post resume delayed work.

The flushed 'hub->init_work' item is used for several purposes, and
is originally initialized with a 'NULL' work function. The work function
is also changed on the fly, which may contribute to the issue.

Solve this by creating a dedicated delayed work item for post resume work,
and flush that delayed work in hub_quiesce()

Cc: stable@kernel.org
Fixes: a49e1e2e785f ("usb: hub: Fix flushing and scheduling of delayed work that tunes runtime pm")
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/linux-usb/aF5rNp1l0LWITnEB@finisterre.sirena.org.uk
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
v3:
 - Rebase on top of a49e1e2e785f ("usb: hub: Fix flushing and scheduling of delayed work that tunes runtime pm")
 - Rewrite commit message 

v2:
 - Add and use dedicated delayed work struct for post resume work
 - Add commit message section about dedicated work


 drivers/usb/core/hub.c | 21 ++++++++-------------
 drivers/usb/core/hub.h |  1 +
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 08562711dcf2..3e1215f7a9a0 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1074,12 +1074,11 @@ int usb_remove_device(struct usb_device *udev)
 
 enum hub_activation_type {
 	HUB_INIT, HUB_INIT2, HUB_INIT3,		/* INITs must come first */
-	HUB_POST_RESET, HUB_RESUME, HUB_RESET_RESUME, HUB_POST_RESUME,
+	HUB_POST_RESET, HUB_RESUME, HUB_RESET_RESUME,
 };
 
 static void hub_init_func2(struct work_struct *ws);
 static void hub_init_func3(struct work_struct *ws);
-static void hub_post_resume(struct work_struct *ws);
 
 static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
 {
@@ -1103,12 +1102,6 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
 		goto init3;
 	}
 
-	if (type == HUB_POST_RESUME) {
-		usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
-		hub_put(hub);
-		return;
-	}
-
 	hub_get(hub);
 
 	/* The superspeed hub except for root hub has to use Hub Depth
@@ -1362,8 +1355,8 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
 		usb_autopm_get_interface_no_resume(
 			to_usb_interface(hub->intfdev));
 
-		INIT_DELAYED_WORK(&hub->init_work, hub_post_resume);
-		queue_delayed_work(system_power_efficient_wq, &hub->init_work,
+		queue_delayed_work(system_power_efficient_wq,
+				   &hub->post_resume_work,
 				   msecs_to_jiffies(USB_SS_PORT_U0_WAKE_TIME));
 		return;
 	}
@@ -1388,9 +1381,10 @@ static void hub_init_func3(struct work_struct *ws)
 
 static void hub_post_resume(struct work_struct *ws)
 {
-	struct usb_hub *hub = container_of(ws, struct usb_hub, init_work.work);
+	struct usb_hub *hub = container_of(ws, struct usb_hub, post_resume_work.work);
 
-	hub_activate(hub, HUB_POST_RESUME);
+	usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
+	hub_put(hub);
 }
 
 enum hub_quiescing_type {
@@ -1418,7 +1412,7 @@ static void hub_quiesce(struct usb_hub *hub, enum hub_quiescing_type type)
 
 	/* Stop hub_wq and related activity */
 	timer_delete_sync(&hub->irq_urb_retry);
-	flush_delayed_work(&hub->init_work);
+	flush_delayed_work(&hub->post_resume_work);
 	usb_kill_urb(hub->urb);
 	if (hub->has_indicators)
 		cancel_delayed_work_sync(&hub->leds);
@@ -1977,6 +1971,7 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
 	hub->hdev = hdev;
 	INIT_DELAYED_WORK(&hub->leds, led_work);
 	INIT_DELAYED_WORK(&hub->init_work, NULL);
+	INIT_DELAYED_WORK(&hub->post_resume_work, hub_post_resume);
 	INIT_WORK(&hub->events, hub_event);
 	INIT_LIST_HEAD(&hub->onboard_devs);
 	spin_lock_init(&hub->irq_urb_lock);
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index e6ae73f8a95d..9ebc5ef54a32 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -70,6 +70,7 @@ struct usb_hub {
 	u8			indicator[USB_MAXCHILDREN];
 	struct delayed_work	leds;
 	struct delayed_work	init_work;
+	struct delayed_work	post_resume_work;
 	struct work_struct      events;
 	spinlock_t		irq_urb_lock;
 	struct timer_list	irq_urb_retry;
-- 
2.43.0