perf_counter, x86: change and remove pmu initialization checks

Some functions are only called if the pmu was proper initialized. That
initalization checks can be removed. The way to check initialization
changed too. Now, the pointer to the interrupt handler is checked. If
it exists the pmu is initialized. This also removes a static variable
and uses struct x86_pmu as only data source for the check.

[ Impact: simplify code ]

Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1241002046-8832-24-git-send-email-robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/cpu/perf_counter.c

@@ -23,7 +23,6 @@
 #include <asm/stacktrace.h>
 #include <asm/nmi.h>
 
-static bool perf_counters_initialized __read_mostly;
 static u64 perf_counter_mask __read_mostly;
 
 struct cpu_hw_counters {
@@ -227,6 +226,11 @@ static void hw_perf_counter_destroy(struct perf_counter *counter)
 	}
 }
 
+static inline int x86_pmu_initialized(void)
+{
+	return x86_pmu.handle_irq != NULL;
+}
+
 /*
  * Setup the hardware configuration for a given hw_event_type
  */
@@ -240,8 +244,8 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
 	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
 		return -ENOSYS;
 
-	if (unlikely(!perf_counters_initialized))
-		return -EINVAL;
+	if (!x86_pmu_initialized())
+		return -ENODEV;
 
 	err = 0;
 	if (atomic_inc_not_zero(&num_counters)) {
@@ -348,9 +352,8 @@ static u64 amd_pmu_save_disable_all(void)
 
 u64 hw_perf_save_disable(void)
 {
-	if (unlikely(!perf_counters_initialized))
+	if (!x86_pmu_initialized())
 		return 0;
-
 	return x86_pmu.save_disable_all();
 }
 /*
@@ -388,9 +391,8 @@ static void amd_pmu_restore_all(u64 ctrl)
 
 void hw_perf_restore(u64 ctrl)
 {
-	if (unlikely(!perf_counters_initialized))
+	if (!x86_pmu_initialized())
 		return;
-
 	x86_pmu.restore_all(ctrl);
 }
 /*
@@ -402,8 +404,6 @@ static inline u64 intel_pmu_get_status(u64 mask)
 {
 	u64 status;
 
-	if (unlikely(!perf_counters_initialized))
-		return 0;
 	rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status);
 
 	return status;
@@ -417,21 +417,13 @@ static inline void intel_pmu_ack_status(u64 ack)
 static inline void x86_pmu_enable_counter(struct hw_perf_counter *hwc, int idx)
 {
 	int err;
-
-	if (unlikely(!perf_counters_initialized))
-		return;
-
 	err = checking_wrmsrl(hwc->config_base + idx,
 			      hwc->config | ARCH_PERFMON_EVENTSEL0_ENABLE);
 }
 
 static inline void x86_pmu_disable_counter(struct hw_perf_counter *hwc, int idx)
 {
 	int err;
-
-	if (unlikely(!perf_counters_initialized))
-		return;
-
 	err = checking_wrmsrl(hwc->config_base + idx,
 			      hwc->config);
 }
@@ -787,10 +779,10 @@ void perf_counter_unthrottle(void)
 {
 	struct cpu_hw_counters *cpuc;
 
-	if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON))
+	if (!x86_pmu_initialized())
 		return;
 
-	if (unlikely(!perf_counters_initialized))
+	if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON))
 		return;
 
 	cpuc = &__get_cpu_var(cpu_hw_counters);
@@ -829,8 +821,9 @@ void perf_counters_lapic_init(int nmi)
 {
 	u32 apic_val;
 
-	if (!perf_counters_initialized)
+	if (!x86_pmu_initialized())
 		return;
+
 	/*
 	 * Enable the performance counter vector in the APIC LVT:
 	 */
@@ -988,7 +981,6 @@ void __init init_hw_perf_counters(void)
 		((1LL << x86_pmu.num_counters_fixed)-1) << X86_PMC_IDX_FIXED;
 
 	pr_info("... counter mask:    %016Lx\n", perf_counter_mask);
-	perf_counters_initialized = true;
 
 	perf_counters_lapic_init(0);
 	register_die_notifier(&perf_counter_nmi_notifier);