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authorAlan Stern <stern@rowland.harvard.edu>2020-04-22 23:09:51 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-04-23 16:22:41 +0300
commit9f952e26295d977dbfc6fedeaf8c4f112c818d37 (patch)
tree7bba4ea8fe10c215634f35128b21807ae3fc05b7 /drivers/usb
parent0df9433fcae02215c8fd79690c134d535c7bb905 (diff)
downloadlinux-9f952e26295d977dbfc6fedeaf8c4f112c818d37.tar.xz
USB: hub: Fix handling of connect changes during sleep
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 <peter.chen@nxp.com> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Fixes: 8099f58f1ecd ("USB: hub: Don't record a connect-change event during reset-resume") Tested-by: Paul Zimmerman <pauldzim@gmail.com> CC: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.2004221602480.11262-100000@iolanthe.rowland.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/core/hub.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 54cd8ef795ec..83549f009ced 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1223,6 +1223,11 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
#ifdef CONFIG_PM
udev->reset_resume = 1;
#endif
+ /* 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 */
@@ -3088,6 +3093,15 @@ static int check_port_resume_type(struct usb_device *udev,
if (portchange & USB_PORT_STAT_C_ENABLE)
usb_clear_port_feature(hub->hdev, port1,
USB_PORT_FEAT_C_ENABLE);
+
+ /*
+ * 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;