[CCing Francesco Dolcini; and the regression list too, as it should be in the loop for regressions: https://docs.kernel.org/admin-guide/reporting-regressions.html] On 16.05.23 14:53, Alistair wrote: > On Fri, 2023-04-07 at 03:07 +0000, Badhri Jagan Sridharan wrote: >> usb_udc_connect_control does not check to see if the udc has already >> been started. This causes gadget->ops->pullup to be called through >> usb_gadget_connect when invoked from usb_udc_vbus_handler even before >> usb_gadget_udc_start is called. Guard this by checking for udc- >>> started >> in usb_udc_connect_control before invoking usb_gadget_connect. > [...] >> Cc: stable@xxxxxxxxxxxxxxx >> Fixes: 628ef0d273a6 ("usb: udc: add usb_udc_vbus_handler") >> Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx> > > This patch causes a kernel hang when trying to boot with the > usb/chipidea/udc.c driver. > > The call stack below causes the hang: > > - gadget_bind_driver(struct device *dev) > - mutex_lock(&udc->connect_lock); > - usb_gadget_udc_start_locked(struct usb_udc *udc) > - udc->gadget->ops->udc_start(udc->gadget, udc->driver) > > At which point we are calling ci_udc_start(..), but with the > connect_lock mutex locked. > > ci_udc_start() then calls usb_udc_vbus_handler() which tries to lock > the connect_lock while it's already locked. Resulting in a kernel hang. > > Reverting this patch fixes the hang. Not my area of expertise, but I guess it might be the same error as this one: https://lore.kernel.org/all/ZF4BvgsOyoKxdPFF@xxxxxxxxxxxxxxxxxxxxxxxxxxxx/ Francesco sent a revert on Friday, but no reaction from Badhri Jagan Sridharan or Greg yet afaics. https://lore.kernel.org/all/20230512131435.205464-1-francesco@xxxxxxxxxx/ Ciao, Thorsten
