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@kernel.org>
Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
Link: https://lore.kernel.org/r/20210917021852.2037-1-wcheng@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 040f2dbd2010 ("usb: dwc3: gadget: Avoid duplicate requests to enable Run/Stop")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index da296f888f45de7c063e823b16c8cfa50a27d9be..a93c61bc5a7dc396aba569ed953c3652365de2ff 100644 (file)
--- 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 80fee7ea83ca44e47e58d0b205d07ab4603b6516..079919b85d87f2d18891ec5adbf2254240e6f5e0 100644 (file)
--- 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);