| Date | Fri, 6 Aug 2021 12:48:35 +0200 | From | Peter Zijlstra <> | Subject | Re: [patch V3 48/64] locking/ww_mutex: Add RT priority to W/W order |
| |
On Thu, Aug 05, 2021 at 05:13:48PM +0200, Thomas Gleixner wrote: > static inline bool > +__ww_ctx_less(struct ww_acquire_ctx *a, struct ww_acquire_ctx *b) > { > +/* > + * Can only do the RT prio for WW_RT because task->prio isn't stable due to PI, > + * so the wait_list ordering will go wobbly. rt_mutex re-queues the waiter and > + * isn't affected by this. > + */ > +#ifdef WW_RT > + /* kernel prio; less is more */ > + int a_prio = a->task->prio; > + int b_prio = b->task->prio; > + > + if (dl_prio(a_prio) || dl_prio(b_prio)) {
Whoever wrote this was an idiot :-) Both should be rt_prio().
> + > + if (a_prio > b_prio) > + return true; > + > + if (a_prio < b_prio) > + return false; > + > + /* equal static prio */ > + > + if (dl_prio(a_prio)) { > + if (dl_time_before(b->task->dl.deadline, > + a->task->dl.deadline)) > + return true; > + > + if (dl_time_before(a->task->dl.deadline, > + b->task->dl.deadline)) > + return false; > + } > + > + /* equal prio */ > + } > +#endif > > + /* FIFO order tie break -- bigger is younger */ > return (signed long)(a->stamp - b->stamp) > 0; > }
|