Messages in this thread | | | Date | Wed, 17 Aug 2022 15:03:37 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 11/14] perf/hw_breakpoint: Reduce contention with large number of tasks |
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On Mon, Jul 04, 2022 at 05:05:11PM +0200, Marco Elver wrote: > +static bool bp_constraints_is_locked(struct perf_event *bp) > +{ > + struct mutex *tsk_mtx = get_task_bps_mutex(bp); > + > + return percpu_is_write_locked(&bp_cpuinfo_sem) || > + (tsk_mtx ? mutex_is_locked(tsk_mtx) : > + percpu_is_read_locked(&bp_cpuinfo_sem)); > +}
> @@ -426,18 +521,28 @@ static int modify_bp_slot(struct perf_event *bp, u64 old_type, u64 new_type) > */ > int dbg_reserve_bp_slot(struct perf_event *bp) > { > - if (mutex_is_locked(&nr_bp_mutex)) > + int ret; > + > + if (bp_constraints_is_locked(bp)) > return -1; > > - return __reserve_bp_slot(bp, bp->attr.bp_type); > + /* Locks aren't held; disable lockdep assert checking. */ > + lockdep_off(); > + ret = __reserve_bp_slot(bp, bp->attr.bp_type); > + lockdep_on(); > + > + return ret; > } > > int dbg_release_bp_slot(struct perf_event *bp) > { > - if (mutex_is_locked(&nr_bp_mutex)) > + if (bp_constraints_is_locked(bp)) > return -1; > > + /* Locks aren't held; disable lockdep assert checking. */ > + lockdep_off(); > __release_bp_slot(bp, bp->attr.bp_type); > + lockdep_on(); > > return 0; > }
Urggghhhh... this is horrible crap. That is, the current code is that and this makes it worse :/
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