Commit 228020b4 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

perf: Re-instate the linear PMU search 



Full revert of commit 9551fbb6 ("perf/core: Remove pmu linear
searching code").

Some architectures (notably arm/arm64) still relied on the linear
search in order to find the PMU that consumes
PERF_TYPE_{HARDWARE,HW_CACHE,RAW}.

This will need a more thorought audit and cleanup.

Reported-by: default avatarNathan Chancellor <nathan@kernel.org>
Reported-by: default avatarKrzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230605101401.GL38236@hirez.programming.kicks-ass.net
parent 10d95a31

kernel/events/core.c

+24 −13
Original line number Diff line number Diff line
@@ -11630,13 +11630,10 @@ static struct pmu *perf_init_event(struct perf_event *event) 
	}



again:

	ret = -ENOENT;

	rcu_read_lock();

	pmu = idr_find(&pmu_idr, type);

	rcu_read_unlock();

	if (!pmu)

		goto fail;



	if (pmu) {

		if (event->attr.type != type && type != PERF_TYPE_RAW &&

		    !(pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE))

			goto fail;
@@ -11647,10 +11644,24 @@ static struct pmu *perf_init_event(struct perf_event *event) 
			goto again;

		}



fail:

		if (ret)

			pmu = ERR_PTR(ret);



		goto unlock;

	}



	list_for_each_entry_rcu(pmu, &pmus, entry, lockdep_is_held(&pmus_srcu)) {

		ret = perf_try_init_event(pmu, event);

		if (!ret)

			goto unlock;



		if (ret != -ENOENT) {

			pmu = ERR_PTR(ret);

			goto unlock;

		}

	}

fail:

	pmu = ERR_PTR(-ENOENT);

unlock:

	srcu_read_unlock(&pmus_srcu, idx);