3.16.83-rc1 review patch. If anyone has any objections, please let me know.
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From: Keiya Nobuta nobuta.keiya@fujitsu.com
commit 9c06ac4c83df6d6fbdbf7488fbad822b4002ba19 upstream.
If hub_activate() is called before D+ has stabilized after remote wakeup, the following situation might occur:
__ ___________________ / \ / D+ __/ __/
Hub _______________________________ | ^ ^ ^ | | | | Host _____v__|___|___________|______ | | | | | | | -- Interrupt Transfer (*3) | | -- ClearPortFeature (*2) | -- GetPortStatus (*1) -- Host detects remote wakeup
- D+ goes high, Host starts running by remote wakeup - D+ is not stable, goes low - Host requests GetPortStatus at (*1) and gets the following hub status: - Current Connect Status bit is 0 - Connect Status Change bit is 1 - D+ stabilizes, goes high - Host requests ClearPortFeature and thus Connect Status Change bit is cleared at (*2) - After waiting 100 ms, Host starts the Interrupt Transfer at (*3) - Since the Connect Status Change bit is 0, Hub returns NAK.
In this case, port_event() is not called in hub_event() and Host cannot recognize device. To solve this issue, flag change_bits even if only Connect Status Change bit is 1 when got in the first GetPortStatus.
This issue occurs rarely because it only if D+ changes during a very short time between GetPortStatus and ClearPortFeature. However, it is fatal if it occurs in embedded system.
Signed-off-by: Keiya Nobuta nobuta.keiya@fujitsu.com Acked-by: Alan Stern stern@rowland.harvard.edu Link: https://lore.kernel.org/r/20200109051448.28150-1-nobuta.keiya@fujitsu.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/core/hub.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -1125,6 +1125,7 @@ static void hub_activate(struct usb_hub * PORT_OVER_CURRENT is not. So check for any of them. */ if (udev || (portstatus & USB_PORT_STAT_CONNECTION) || + (portchange & USB_PORT_STAT_C_CONNECTION) || (portstatus & USB_PORT_STAT_OVERCURRENT) || (portchange & USB_PORT_STAT_C_OVERCURRENT)) set_bit(port1, hub->change_bits);