> On busy networks the CAN controller might receive CAN frames directly
> after starting it but before the timecounter is setup. This will lead
> to NULL pointer deref while converting the converting the CAN frame's
> timestamp with the timecounter.
>
> Close the race window by setting up the timecounter before starting
> the CAN controller.
My logic of starting the timer after the USB request to start was due to the function returning before if the USB start request returns an error. With this change, the timer will be started and poll the USB timestamp request even if the device is not started - I tested and confirmed this is the case.
I agree with the issue this patch solves and flaw previously but believe it requires a check of the GS_CAN_FEATURE_HW_TIMESTAMP and gs_usb_timestamp_stop(dev) in the rc < 0 check.
if (rc < 0) {
netdev_err(netdev, "Couldn't start device (err=%d)\n", rc);
kfree(dm);
/* stop polling timestamp */
if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
gs_usb_timestamp_stop(dev);
return rc;
}
John.
