Hi, Alan Stern wrote: > On Mon, Jan 11, 2021 at 12:38:05PM -0800, Thinh Nguyen wrote: >> For some UDCs, the initialization sequence by udc_start() should not be >> repeated until it is properly cleaned up with udc_stop() and vise versa. >> We may run into some cleanup failure as seen with the DWC3 driver during >> the irq cleanup. This issue can occur when the user triggers >> soft-connect/soft-disconnect from the soft_connect sysfs. To avoid >> adding checks to every UDC driver, at the UDC framework, introduce a >> "started" state to track and prevent the UDC from repeating the >> udc_start() and udc_stop() if it had already started/stopped. >> >> Signed-off-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> > Is the new "started" field subject to races? What happens if there are > concurrent requests to start and stop the UDC? > > Alan Stern The caller of this usb_gadget_udc_start/stop() should take care of the locking. It's already done in the case of driver probe/remove, but not for the sysfs soft_connect. Maybe I should add that to this patch. Thanks, Thinh
