blob: c99c41ff8c30471f31c3636a31090d39e9864fb4 [file] [log] [blame]
From 17401e36f7b1a96d6202e50c19c2f738b0068aad Mon Sep 17 00:00:00 2001
From: Alan Stern <>
Date: Wed, 22 Apr 2020 16:09:51 -0400
Subject: [PATCH] USB: hub: Fix handling of connect changes during sleep
commit 9f952e26295d977dbfc6fedeaf8c4f112c818d37 upstream.
Commit 8099f58f1ecd ("USB: hub: Don't record a connect-change event
during reset-resume") wasn't very well conceived. The problem it
tried to fix was that if a connect-change event occurred while the
system was asleep (such as a device disconnecting itself from the bus
when it is suspended and then reconnecting when it resumes)
requiring a reset-resume during the system wakeup transition, the hub
port's change_bit entry would remain set afterward. This would cause
the hub driver to believe another connect-change event had occurred
after the reset-resume, which was wrong and would lead the driver to
send unnecessary requests to the device (which could interfere with a
firmware update).
The commit tried to fix this by not setting the change_bit during the
wakeup. But this was the wrong thing to do; it means that when a
device is unplugged while the system is asleep, the hub driver doesn't
realize anything has happened: The change_bit flag which would tell it
to handle the disconnect event is clear.
The commit needs to be reverted and the problem fixed in a different
way. Fortunately an alternative solution was noted in the commit's
Changelog: We can continue to set the change_bit entry in
hub_activate() but then clear it when a reset-resume occurs. That way
the the hub driver will see the change_bit when a device is
disconnected but won't see it when the device is still present.
That's what this patch does.
Reported-and-tested-by: Peter Chen <>
Signed-off-by: Alan Stern <>
Fixes: 8099f58f1ecd ("USB: hub: Don't record a connect-change event during reset-resume")
Tested-by: Paul Zimmerman <>
CC: <>
Signed-off-by: Greg Kroah-Hartman <>
Signed-off-by: Paul Gortmaker <>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index a54d0c8971e6..b5b36f5d2203 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1218,6 +1218,11 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
#ifdef CONFIG_PM
udev->reset_resume = 1;
+ /* Don't set the change_bits when the device
+ * was powered off.
+ */
+ if (test_bit(port1, hub->power_bits))
+ set_bit(port1, hub->change_bits);
} else {
/* The power session is gone; tell hub_wq */
@@ -3081,6 +3086,15 @@ static int check_port_resume_type(struct usb_device *udev,
if (portchange & USB_PORT_STAT_C_ENABLE)
usb_clear_port_feature(hub->hdev, port1,
+ /*
+ * Whatever made this reset-resume necessary may have
+ * turned on the port1 bit in hub->change_bits. But after
+ * a successful reset-resume we want the bit to be clear;
+ * if it was on it would indicate that something happened
+ * following the reset-resume.
+ */
+ clear_bit(port1, hub->change_bits);
return status;