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| author | Wesley Cheng <wcheng@codeaurora.org> | 2021-09-16 19:18:52 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-21 16:35:03 +0200 |
| commit | 8217f07a50236779880f13e87f99224cd9117f83 (patch) | |
| tree | b2818c1e342b8560abf1ff5bb713be38dd7a8ecf /drivers/usb/dwc3/gadget.c | |
| parent | a8426a43b0c0f257a090f8551d6b09b79b8095e5 (diff) | |
| download | lwn-8217f07a50236779880f13e87f99224cd9117f83.tar.gz lwn-8217f07a50236779880f13e87f99224cd9117f83.zip | |
usb: dwc3: gadget: Avoid starting DWC3 gadget during UDC unbind
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>
Diffstat (limited to 'drivers/usb/dwc3/gadget.c')
| -rw-r--r-- | drivers/usb/dwc3/gadget.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 804b50548163..32e01885b211 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -2418,7 +2418,7 @@ 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. @@ -4352,7 +4352,7 @@ 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); |