[PATCH 2/4] perf_events: x86: Clean up hw_perf_*_all() implementation

[Peter Zijlstra]

Put the recursion avoidance code in the generic hook instead of
replicating it in each implementation.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
---
Index: linux-2.6/arch/x86/kernel/cpu/perf_event.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/perf_event.c
+++ linux-2.6/arch/x86/kernel/cpu/perf_event.c
@@ -1099,15 +1099,8 @@ static int __hw_perf_event_init(struct p
 
 static void p6_pmu_disable_all(void)
 {
-	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 	u64 val;
 
-	if (!cpuc->enabled)
-		return;
-
-	cpuc->enabled = 0;
-	barrier();
-
 	/* p6 only has one enable register */
 	rdmsrl(MSR_P6_EVNTSEL0, val);
 	val &= ~ARCH_PERFMON_EVENTSEL0_ENABLE;
@@ -1118,12 +1111,6 @@ static void intel_pmu_disable_all(void)
 {
 	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 
-	if (!cpuc->enabled)
-		return;
-
-	cpuc->enabled = 0;
-	barrier();
-
 	wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0);
 
 	if (test_bit(X86_PMC_IDX_FIXED_BTS, cpuc->active_mask))
@@ -1135,17 +1122,6 @@ static void amd_pmu_disable_all(void)
 	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 	int idx;
 
-	if (!cpuc->enabled)
-		return;
-
-	cpuc->enabled = 0;
-	/*
-	 * ensure we write the disable before we start disabling the
-	 * events proper, so that amd_pmu_enable_event() does the
-	 * right thing.
-	 */
-	barrier();
-
 	for (idx = 0; idx < x86_pmu.num_events; idx++) {
 		u64 val;
 
@@ -1166,23 +1142,20 @@ void hw_perf_disable(void)
 	if (!x86_pmu_initialized())
 		return;
 
-	if (cpuc->enabled)
-		cpuc->n_added = 0;
+	if (!cpuc->enabled)
+		return;
+
+	cpuc->n_added = 0;
+	cpuc->enabled = 0;
+	barrier();
 
 	x86_pmu.disable_all();
 }
 
 static void p6_pmu_enable_all(void)
 {
-	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 	unsigned long val;
 
-	if (cpuc->enabled)
-		return;
-
-	cpuc->enabled = 1;
-	barrier();
-
 	/* p6 only has one enable register */
 	rdmsrl(MSR_P6_EVNTSEL0, val);
 	val |= ARCH_PERFMON_EVENTSEL0_ENABLE;
@@ -1193,12 +1166,6 @@ static void intel_pmu_enable_all(void)
 {
 	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 
-	if (cpuc->enabled)
-		return;
-
-	cpuc->enabled = 1;
-	barrier();
-
 	wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, x86_pmu.intel_ctrl);
 
 	if (test_bit(X86_PMC_IDX_FIXED_BTS, cpuc->active_mask)) {
@@ -1217,12 +1184,6 @@ static void amd_pmu_enable_all(void)
 	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 	int idx;
 
-	if (cpuc->enabled)
-		return;
-
-	cpuc->enabled = 1;
-	barrier();
-
 	for (idx = 0; idx < x86_pmu.num_events; idx++) {
 		struct perf_event *event = cpuc->events[idx];
 		u64 val;
@@ -1417,6 +1378,10 @@ void hw_perf_enable(void)
 
 	if (!x86_pmu_initialized())
 		return;
+
+	if (cpuc->enabled)
+		return;
+
 	if (cpuc->n_added) {
 		/*
 		 * apply assignment obtained either from
@@ -1461,6 +1426,10 @@ void hw_perf_enable(void)
 		cpuc->n_added = 0;
 		perf_events_lapic_init();
 	}
+
+	cpuc->enabled = 1;
+	barrier();
+
 	x86_pmu.enable_all();
 }
 

-- 

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