linux-kernel - [PATCH 09/19] perf: Merge pmu_disable_count into cpu_pmu

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Message-Id: <20241104135518.518730578@infradead.org>
Date: Mon, 04 Nov 2024 14:39:18 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: mingo@...nel.org,
 lucas.demarchi@...el.com
Cc: linux-kernel@...r.kernel.org,
 peterz@...radead.org,
 willy@...radead.org,
 acme@...nel.org,
 namhyung@...nel.org,
 mark.rutland@....com,
 alexander.shishkin@...ux.intel.com,
 jolsa@...nel.org,
 irogers@...gle.com,
 adrian.hunter@...el.com,
 kan.liang@...ux.intel.com
Subject: [PATCH 09/19] perf: Merge pmu_disable_count into cpu_pmu_context

Because it makes no sense to have two per-cpu allocations per pmu.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 include/linux/perf_event.h |    2 +-
 kernel/events/core.c       |   12 ++++--------
 2 files changed, 5 insertions(+), 9 deletions(-)

--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -336,7 +336,6 @@ struct pmu {
 	 */
 	unsigned int			scope;
 
-	int __percpu			*pmu_disable_count;
 	struct perf_cpu_pmu_context __percpu *cpu_pmu_context;
 	atomic_t			exclusive_cnt; /* < 0: cpu; > 0: tsk */
 	int				task_ctx_nr;
@@ -1010,6 +1009,7 @@ struct perf_cpu_pmu_context {
 
 	int				active_oncpu;
 	int				exclusive;
+	int				pmu_disable_count;
 
 	raw_spinlock_t			hrtimer_lock;
 	struct hrtimer			hrtimer;
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1178,21 +1178,22 @@ static int perf_mux_hrtimer_restart_ipi(
 
 void perf_pmu_disable(struct pmu *pmu)
 {
-	int *count = this_cpu_ptr(pmu->pmu_disable_count);
+	int *count = &this_cpu_ptr(pmu->cpu_pmu_context)->pmu_disable_count;
 	if (!(*count)++)
 		pmu->pmu_disable(pmu);
 }
 
 void perf_pmu_enable(struct pmu *pmu)
 {
-	int *count = this_cpu_ptr(pmu->pmu_disable_count);
+	int *count = &this_cpu_ptr(pmu->cpu_pmu_context)->pmu_disable_count;
 	if (!--(*count))
 		pmu->pmu_enable(pmu);
 }
 
 static void perf_assert_pmu_disabled(struct pmu *pmu)
 {
-	WARN_ON_ONCE(*this_cpu_ptr(pmu->pmu_disable_count) == 0);
+	int *count = &this_cpu_ptr(pmu->cpu_pmu_context)->pmu_disable_count;
+	WARN_ON_ONCE(*count == 0);
 }
 
 static void get_ctx(struct perf_event_context *ctx)
@@ -11758,7 +11759,6 @@ static bool idr_cmpxchg(struct idr *idr,
 
 static void perf_pmu_free(struct pmu *pmu)
 {
-	free_percpu(pmu->pmu_disable_count);
 	if (pmu_bus_running && pmu->dev && pmu->dev != PMU_NULL_DEV) {
 		if (pmu->nr_addr_filters)
 			device_remove_file(pmu->dev, &dev_attr_nr_addr_filters);
@@ -11777,10 +11777,6 @@ int perf_pmu_register(struct pmu *_pmu,
 	struct pmu *pmu __free(pmu_unregister) = _pmu;
 	guard(mutex)(&pmus_lock);
 
-	pmu->pmu_disable_count = alloc_percpu(int);
-	if (!pmu->pmu_disable_count)
-		return -ENOMEM;
-
 	if (WARN_ONCE(!name, "Can not register anonymous pmu.\n"))
 		return -EINVAL;