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usb: gadget: core: flush gadget workqueue after device removal

PATCH In review Roy Luo 3 participants 3 messages Feb 4, 2025 – Feb 12, 2025

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Roy Luo

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#0 lore raw

PATCH v2 1/1 usb: gadget: core: flush gadget workqueue after device removal

device_del() can lead to new work being scheduled in gadget->work workqueue. This is observed, for example, with the dwc3 driver with the following call stack:
device_del()

    gadget_unbind_driver()
      usb_gadget_disconnect_locked()
        dwc3_gadget_pullup()
	  dwc3_gadget_soft_disconnect()
	    usb_gadget_set_state()
	      schedule_work(&gadget->work)

Move flush_work() after device_del() to ensure the workqueue is cleaned up.

Fixes 5702f75375aa9 ("usb: gadget: udc-core: move sysfs_notify() to a workqueue")
Cc <[email protected]>
Signed-off-by Roy Luo <[email protected]>
---
 drivers/usb/gadget/udc/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/usb/gadget/udc/core.c +1 -1
index a6f46364be65..4b3d5075621a 100644
@@ -1543,8 +1543,8 @@ void usb_del_gadget(struct usb_gadget *gadget)
 
 	kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
 	sysfs_remove_link(&udc->dev.kobj, "gadget");
-	flush_work(&gadget->work);
 	device_del(&gadget->dev);
+	flush_work(&gadget->work);
 	ida_free(&gadget_id_numbers, gadget->id_number);
 	cancel_work_sync(&udc->vbus_work);
 	device_unregister(&udc->dev);

base-commit: f286757b644c226b6b31779da95a4fa7ab245ef5

Signature · 1 line
2.48.1.362.g079036d154-goog
Reviewed-by on v2 1/1
#1 lore raw
Quoted 11 lines · Roy Luo

device_del() can lead to new work being scheduled in gadget->work workqueue. This is observed, for example, with the dwc3 driver with the following call stack:
device_del()

    gadget_unbind_driver()
      usb_gadget_disconnect_locked()
        dwc3_gadget_pullup()
	  dwc3_gadget_soft_disconnect()
	    usb_gadget_set_state()
	      schedule_work(&gadget->work)
Quoted 7 lines

Move flush_work() after device_del() to ensure the workqueue is cleaned up.

Fixes 5702f75375aa9 ("usb: gadget: udc-core: move sysfs_notify() to a workqueue")
Cc <[email protected]>
Signed-off-by Roy Luo <[email protected]>

---

Reviewed-by Alan Stern <[email protected]>
Quoted 22 lines
 drivers/usb/gadget/udc/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/usb/gadget/udc/core.c +1 -1
index a6f46364be65..4b3d5075621a 100644
@@ -1543,8 +1543,8 @@ void usb_del_gadget(struct usb_gadget *gadget)
 
 	kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
 	sysfs_remove_link(&udc->dev.kobj, "gadget");
-	flush_work(&gadget->work);
 	device_del(&gadget->dev);
+	flush_work(&gadget->work);
 	ida_free(&gadget_id_numbers, gadget->id_number);
 	cancel_work_sync(&udc->vbus_work);
 	device_unregister(&udc->dev);

base-commit: f286757b644c226b6b31779da95a4fa7ab245ef5

Signature · 1 line
2.48.1.362.g079036d154-goog
Reviewed-by on v2 1/1
#2 lore raw
In reply to Roy Luo
Quoted 36 lines · Roy Luo

device_del() can lead to new work being scheduled in gadget->work workqueue. This is observed, for example, with the dwc3 driver with the following call stack:
device_del()

    gadget_unbind_driver()
      usb_gadget_disconnect_locked()
        dwc3_gadget_pullup()
	  dwc3_gadget_soft_disconnect()
	    usb_gadget_set_state()
	      schedule_work(&gadget->work)

Move flush_work() after device_del() to ensure the workqueue is cleaned up.

Fixes 5702f75375aa9 ("usb: gadget: udc-core: move sysfs_notify() to a workqueue")
Cc <[email protected]>
Signed-off-by Roy Luo <[email protected]>
---
 drivers/usb/gadget/udc/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/usb/gadget/udc/core.c +1 -1
index a6f46364be65..4b3d5075621a 100644
@@ -1543,8 +1543,8 @@ void usb_del_gadget(struct usb_gadget *gadget)
 
 	kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
 	sysfs_remove_link(&udc->dev.kobj, "gadget");
-	flush_work(&gadget->work);
 	device_del(&gadget->dev);
+	flush_work(&gadget->work);
 	ida_free(&gadget_id_numbers, gadget->id_number);
 	cancel_work_sync(&udc->vbus_work);
 	device_unregister(&udc->dev);
Quoted 4 lines

base-commit: f286757b644c226b6b31779da95a4fa7ab245ef5

Signature · 1 line
2.48.1.362.g079036d154-goog
Reviewed-by Thinh Nguyen <[email protected]>

Thanks,
Thinh