On 28.01.22 12:12, Oleksij Rempel wrote: > The user space should get an event in case there is a problem with the > USB transfers, i.e. the URB status is != 0. That would need filtering for unlinks, but that is a detail > The use space then can decide if the USB device needs to be reset, power > cycled and so on. This is highly problematic. Not necessarily impossible but problematic. Executing URBs is part of the * device removal and addition IO paths * block IO path * SCSI error handling * PM transition IO paths While we can send messages to user space, we cannot allocate a lot of memory and we cannot wait for responses. > What about calling a to-be-written devlink function that reports the USB > status if the URB status is not 0: > > diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c > index d0f45600b669..a90134854f32 100644 > --- a/drivers/usb/core/hcd.c > +++ b/drivers/usb/core/hcd.c > @@ -1648,6 +1648,8 @@ static void __usb_hcd_giveback_urb(struct urb *urb) > usb_unanchor_urb(urb); > if (likely(status == 0)) > usb_led_activity(USB_LED_EVENT_HOST); > + else > + devlink_report_usb_status(urb, status); > > It seems to me that you are approaching this issue on too low a level. Drivers generally do at least rudimentary error handling or rather detection. This would be easy to use if you gave them a nice API. Something like: devlink_report_urb_error(usb_interface * intf, int reason, bool handling); Maybe also report resets and hub events from the hub driver and I think you'd get what you need. You need to be aware of a need for some kind of limiting logic for disconnects. The change over from logging something not very helpful to properly reporting is easy. Regards Oliver
