block completion races

Also, there is this code in ide_do_drive_cmd():

        if (action == ide_wait) {
                wait_for_completion(&wait);     /* wait for it to be serviced */
                return rq->errors ? -EIO : 0;   /* return -EIO if errors */
        }

Is it safe to use `rq' here? It has just been recycled in end_that_request_last() and we don't own it any more.

Quoted 7 lines

Also, there is this code in ide_do_drive_cmd():

        if (action == ide_wait) {
                wait_for_completion(&wait);     /* wait for it to be serviced */
                return rq->errors ? -EIO : 0;   /* return -EIO if errors */
        }

Quoted 3 lines

Is it safe to use `rq' here? It has just been recycled in end_that_request_last() and we don't own it any more.

Yes, this is safe. rq lies on the stack of the caller of ide_do_drive_cmd() - it can't disappear before we return.