On 17.05.23 12:35, Francesco Dolcini wrote: > On Wed, May 17, 2023 at 12:23:39PM +0200, Linux regression tracking (Thorsten Leemhuis) wrote: >> [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/ > > Revert patches were applied and are in linux-next. I expect those to > land in Linus tree with the next pull request from Greg. Ha, sorry, I missed that, as I only looked at lore. Should have looked in my own regression tracking, there it's marked as "fix incoming", as regzbot noticed the fix in next... Ciao, Thorsten
