Patch "usb: dwc3: gadget: Avoid starting DWC3 gadget during UDC unbind" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    usb: dwc3: gadget: Avoid starting DWC3 gadget during UDC unbind

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-dwc3-gadget-avoid-starting-dwc3-gadget-during-ud.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 147c1d5a2c2ca977e7c37d665b33646dfa0c5860
Author: Wesley Cheng <wcheng@xxxxxxxxxxxxxx>
Date:   Thu Sep 16 19:18:52 2021 -0700

    usb: dwc3: gadget: Avoid starting DWC3 gadget during UDC unbind
    
    [ Upstream commit 8217f07a50236779880f13e87f99224cd9117f83 ]
    
    There is a race present where the DWC3 runtime resume runs in parallel
    to the UDC unbind sequence.  This will eventually lead to a possible
    scenario where we are enabling the run/stop bit, without a valid
    composition defined.
    
    Thread#1 (handling UDC unbind):
    usb_gadget_remove_driver()
    -->usb_gadget_disconnect()
      -->dwc3_gadget_pullup(0)
    --> continue UDC unbind sequence
    -->Thread#2 is running in parallel here
    
    Thread#2 (handing next cable connect)
    __dwc3_set_mode()
      -->pm_runtime_get_sync()
        -->dwc3_gadget_resume()
          -->dwc->gadget_driver is NOT NULL yet
          -->dwc3_gadget_run_stop(1)
          --> _dwc3gadget_start()
    ...
    
    Fix this by tracking the pullup disable routine, and avoiding resuming
    of the DWC3 gadget.  Once the UDC is re-binded, that will trigger the
    pullup enable routine, which would handle enabling the DWC3 gadget.
    
    Acked-by: Felipe Balbi <balbi@xxxxxxxxxx>
    Signed-off-by: Wesley Cheng <wcheng@xxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20210917021852.2037-1-wcheng@xxxxxxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Stable-dep-of: 040f2dbd2010 ("usb: dwc3: gadget: Avoid duplicate requests to enable Run/Stop")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index da296f888f45..a93c61bc5a7d 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -994,6 +994,7 @@ struct dwc3_scratchpad_array {
  * @tx_max_burst_prd: max periodic ESS transmit burst size
  * @hsphy_interface: "utmi" or "ulpi"
  * @connected: true when we're connected to a host, false otherwise
+ * @softconnect: true when gadget connect is called, false when disconnect runs
  * @delayed_status: true when gadget driver asks for delayed status
  * @ep0_bounced: true when we used bounce buffer
  * @ep0_expect_in: true when we expect a DATA IN transfer
@@ -1196,6 +1197,7 @@ struct dwc3 {
 	const char		*hsphy_interface;
 
 	unsigned		connected:1;
+	unsigned		softconnect:1;
 	unsigned		delayed_status:1;
 	unsigned		ep0_bounced:1;
 	unsigned		ep0_expect_in:1;
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 80fee7ea83ca..079919b85d87 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2015,7 +2015,7 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 	int			ret;
 
 	is_on = !!is_on;
-
+	dwc->softconnect = is_on;
 	/*
 	 * Per databook, when we want to stop the gadget, if a control transfer
 	 * is still in process, complete it and get the core into setup phase.
@@ -3791,7 +3791,7 @@ int dwc3_gadget_resume(struct dwc3 *dwc)
 {
 	int			ret;
 
-	if (!dwc->gadget_driver)
+	if (!dwc->gadget_driver || !dwc->softconnect)
 		return 0;
 
 	ret = __dwc3_gadget_start(dwc);