On 08/17, Roland McGrath wrote: > > @@ -1033,6 +1042,18 @@ int utrace_control(struct task_struct *target, > if (unlikely(action > UTRACE_DETACH)) > return -EINVAL; > > + /* > + * This is a sanity check for a programming error in the caller. > + * Their request can only work properly in all cases by relying on > + * a follow-up callback, but they didn't set one up! This check > + * doesn't do locking, but it shouldn't matter. The caller has to > + * be synchronously sure the callback is set up to be operating the > + * interface properly. > + */ > + if (action >= UTRACE_REPORT && action < UTRACE_RESUME && > + unlikely(!(engine->flags & UTRACE_EVENT(QUIESCE)))) > + return -EINVAL;
Agreed, this can help to catch the problems. Unfortunately, this doesn't help if a module doesn't use utrace_control() but just returns UTRACE_SINGLESTEP/etc. Like Srikar's test-case does. But I guess we can do nothing in this case, except perhaps we could add pr_debug() into finish_callback(). I dunno. And in any case, the warning from finish_callback() can't be always correct. Oleg.
