[PATCH 5.15 005/148] usb: dwc3: gadget: Avoid starting DWC3 gadget during UDC unbind

Greg Kroah-Hartman
2022-09-26T11:10:19Z

From: Wesley Cheng <wcheng@codeaurora.org>

[ 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>
---
drivers/usb/dwc3/core.h | 2 ++
drivers/usb/dwc3/gadget.c | 4 ++--
2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index fd5d42ec5350..dbae57725f52 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1028,6 +1028,7 @@ struct dwc3_scratchpad_array {
* @tx_fifo_resize_max_num: max number of fifos allocated during txfifo resize
* @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
@@ -1247,6 +1248,7 @@ 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 322754a7f91c..5f9a0ab09f4b 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2442,7 +2442,7 @@ 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.
@@ -4421,7 +4421,7 @@ 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);
--
2.35.1