linux-kernel - [PATCH v3 48/57] perf: Simplify perf_init

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Message-ID: <20230612093541.025480679@infradead.org>
Date:   Mon, 12 Jun 2023 11:08:01 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     torvalds@...ux-foundation.org, keescook@...omium.org,
        gregkh@...uxfoundation.org, pbonzini@...hat.com
Cc:     masahiroy@...nel.org, nathan@...nel.org, ndesaulniers@...gle.com,
        nicolas@...sle.eu, catalin.marinas@....com, will@...nel.org,
        vkoul@...nel.org, trix@...hat.com, ojeda@...nel.org,
        peterz@...radead.org, mingo@...hat.com, longman@...hat.com,
        boqun.feng@...il.com, dennis@...nel.org, tj@...nel.org,
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        luc.vanoostenryck@...il.com
Subject: [PATCH v3 48/57] perf: Simplify perf_init_event()


Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/events/core.c |   31 ++++++++++++-------------------
 1 file changed, 12 insertions(+), 19 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11504,10 +11504,10 @@ static int perf_try_init_event(struct pm
 static struct pmu *perf_init_event(struct perf_event *event)
 {
 	bool extended_type = false;
-	int idx, type, ret;
 	struct pmu *pmu;
+	int type, ret;
 
-	idx = srcu_read_lock(&pmus_srcu);
+	guard(srcu)(&pmus_srcu);
 
 	/*
 	 * Save original type before calling pmu->event_init() since certain
@@ -11520,7 +11520,7 @@ static struct pmu *perf_init_event(struc
 		pmu = event->parent->pmu;
 		ret = perf_try_init_event(pmu, event);
 		if (!ret)
-			goto unlock;
+			return pmu;
 	}
 
 	/*
@@ -11539,13 +11539,12 @@ static struct pmu *perf_init_event(struc
 	}
 
 again:
-	rcu_read_lock();
-	pmu = idr_find(&pmu_idr, type);
-	rcu_read_unlock();
+	scoped_guard (rcu)
+		pmu = idr_find(&pmu_idr, type);
 	if (pmu) {
 		if (event->attr.type != type && type != PERF_TYPE_RAW &&
 		    !(pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE))
-			goto fail;
+			return ERR_PTR(-ENOENT);
 
 		ret = perf_try_init_event(pmu, event);
 		if (ret == -ENOENT && event->attr.type != type && !extended_type) {
@@ -11554,27 +11553,21 @@ static struct pmu *perf_init_event(struc
 		}
 
 		if (ret)
-			pmu = ERR_PTR(ret);
+			return ERR_PTR(ret);
 
-		goto unlock;
+		return pmu;
 	}
 
 	list_for_each_entry_rcu(pmu, &pmus, entry, lockdep_is_held(&pmus_srcu)) {
 		ret = perf_try_init_event(pmu, event);
 		if (!ret)
-			goto unlock;
+			return pmu;
 
-		if (ret != -ENOENT) {
-			pmu = ERR_PTR(ret);
-			goto unlock;
-		}
+		if (ret != -ENOENT)
+			return ERR_PTR(ret);
 	}
-fail:
-	pmu = ERR_PTR(-ENOENT);
-unlock:
-	srcu_read_unlock(&pmus_srcu, idx);
 
-	return pmu;
+	return ERR_PTR(-ENOENT);
 }
 
 static void attach_sb_event(struct perf_event *event)