linux-kernel - [PATCH 1/2] usb: core: Centralize device state update logic

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Message-ID: <20251013-usbcore-tracing-v1-1-b885a3121b09@google.com>
Date: Mon, 13 Oct 2025 10:01:22 +0800
From: Kuen-Han Tsai <khtsai@...gle.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Mathias Nyman <mathias.nyman@...ux.intel.com>, Alan Stern <stern@...land.harvard.edu>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Kuen-Han Tsai <khtsai@...gle.com>
Subject: [PATCH 1/2] usb: core: Centralize device state update logic

Introduce a new static inline function, update_usb_device_state(), to
centralize the process of changing a device's state, including the
management of active_duration during suspend/resume transitions.

This change prepares for adding tracepoints, allowing tracing logic to
be added in a single, central location within the new helper function.

Signed-off-by: Kuen-Han Tsai <khtsai@...gle.com>
---
 drivers/usb/core/hub.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 256fe8c86828d51c33442345acdb7f3fe80a98ce..ce3d94c960470e9be7979b1021551eab5fd03517 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2147,6 +2147,20 @@ static void update_port_device_state(struct usb_device *udev)
 	}
 }
 
+static inline void update_usb_device_state(struct usb_device *udev,
+					   enum usb_device_state new_state)
+{
+	if (udev->state == USB_STATE_SUSPENDED &&
+	    new_state != USB_STATE_SUSPENDED)
+		udev->active_duration -= jiffies;
+	else if (new_state == USB_STATE_SUSPENDED &&
+		 udev->state != USB_STATE_SUSPENDED)
+		udev->active_duration += jiffies;
+
+	udev->state = new_state;
+	update_port_device_state(udev);
+}
+
 static void recursively_mark_NOTATTACHED(struct usb_device *udev)
 {
 	struct usb_hub *hub = usb_hub_to_struct_hub(udev);
@@ -2156,10 +2170,7 @@ static void recursively_mark_NOTATTACHED(struct usb_device *udev)
 		if (hub->ports[i]->child)
 			recursively_mark_NOTATTACHED(hub->ports[i]->child);
 	}
-	if (udev->state == USB_STATE_SUSPENDED)
-		udev->active_duration -= jiffies;
-	udev->state = USB_STATE_NOTATTACHED;
-	update_port_device_state(udev);
+	update_usb_device_state(udev, USB_STATE_NOTATTACHED);
 }
 
 /**
@@ -2209,14 +2220,7 @@ void usb_set_device_state(struct usb_device *udev,
 			else
 				wakeup = 0;
 		}
-		if (udev->state == USB_STATE_SUSPENDED &&
-			new_state != USB_STATE_SUSPENDED)
-			udev->active_duration -= jiffies;
-		else if (new_state == USB_STATE_SUSPENDED &&
-				udev->state != USB_STATE_SUSPENDED)
-			udev->active_duration += jiffies;
-		udev->state = new_state;
-		update_port_device_state(udev);
+		update_usb_device_state(udev, new_state);
 	} else
 		recursively_mark_NOTATTACHED(udev);
 	spin_unlock_irqrestore(&device_state_lock, flags);

-- 
2.51.0.740.g6adb054d12-goog