> Now, if we race with another task doing utrace_task_alloc() and see > ->utrace != NULL, why should we see the correctly initialized *utrace? > > utrace_task_alloc() needs wmb(), and the code like above > read_barrier_depends().
Ok. Please review what I put in (esp. commit c575558) and send patches relative to the latest tree if that's not right. Perhaps it is overkill to do read_barrier_depends() in task_utrace_struct(). But AFAICT if we don't actually need it all those places, that is only because of some less-obvious barrier effect with checks on ->utrace_flags or something. Do you think it's not really needed in all those places we extract the pointer before spin_lock et al? Thanks, Roland
