linux-kernel - [tip: perf/core] perf/core: Simplify perf_init

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Message-ID: <174085965416.10177.16488182367399775052.tip-bot2@tip-bot2>
Date: Sat, 01 Mar 2025 20:07:34 -0000
From: "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Ingo Molnar <mingo@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: perf/core] perf/core: Simplify perf_init_event()

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     9954ea69de5c06c5bf073d366d6768c1c4a2a1c7
Gitweb:        https://git.kernel.org/tip/9954ea69de5c06c5bf073d366d6768c1c4a2a1c7
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Mon, 04 Nov 2024 14:39:16 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Sat, 01 Mar 2025 19:54:05 +01:00

perf/core: Simplify perf_init_event()

Use the <linux/cleanup.h> guard() and scoped_guard() infrastructure
to simplify the control flow.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/20241104135518.302444446@infradead.org
---
 kernel/events/core.c | 31 ++++++++++++-------------------
 1 file changed, 12 insertions(+), 19 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 215dad5..fd35236 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12101,10 +12101,10 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
 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
@@ -12117,7 +12117,7 @@ static struct pmu *perf_init_event(struct perf_event *event)
 		pmu = event->parent->pmu;
 		ret = perf_try_init_event(pmu, event);
 		if (!ret)
-			goto unlock;
+			return pmu;
 	}
 
 	/*
@@ -12136,13 +12136,12 @@ static struct pmu *perf_init_event(struct perf_event *event)
 	}
 
 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) {
@@ -12151,27 +12150,21 @@ again:
 		}
 
 		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)