perf counters: clean up state transitions

Impact: cleanup

Introduce a proper enum for the 3 states of a counter:

	PERF_COUNTER_STATE_OFF		= -1
	PERF_COUNTER_STATE_INACTIVE	=  0
	PERF_COUNTER_STATE_ACTIVE	=  1

and rename counter->active to counter->state and propagate the
changes everywhere.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 25 insertions, 17 deletions

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 3e1dbebe22b9..4854cca7fffd 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -332,7 +332,7 @@ perf_handle_group(struct perf_counter *sibling, u64 *status, u64 *overflown)
          * Then store sibling timestamps (if any):
          */
         list_for_each_entry(counter, &group_leader->sibling_list, list_entry) {
-                if (!counter->active) {
+                if (counter->state != PERF_COUNTER_STATE_ACTIVE) {
                         /*
                          * When counter was not in the overflow mask, we have to
                          * read it from hardware. We read it as well, when it
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 97d86c293ee8..8cb095fa442c 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -128,6 +128,15 @@ struct hw_perf_counter_ops {
 };
 
 /**
+ * enum perf_counter_active_state - the states of a counter
+ */
+enum perf_counter_active_state {
+        PERF_COUNTER_STATE_OFF          = -1,
+        PERF_COUNTER_STATE_INACTIVE     =  0,
+        PERF_COUNTER_STATE_ACTIVE       =  1,
+};
+
+/**
  * struct perf_counter - performance counter kernel representation:
  */
 struct perf_counter {
@@ -136,7 +145,7 @@ struct perf_counter {
         struct perf_counter             *group_leader;
         const struct hw_perf_counter_ops *hw_ops;
 
-        int                             active;
+        enum perf_counter_active_state  state;
 #if BITS_PER_LONG == 64
         atomic64_t                      count;
 #else
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 4e679b91d8bb..559130b8774d 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -167,9 +167,9 @@ static void __perf_counter_remove_from_context(void *info)
 
         spin_lock(&ctx->lock);
 
-        if (counter->active) {
+        if (counter->state == PERF_COUNTER_STATE_ACTIVE) {
                 counter->hw_ops->hw_perf_counter_disable(counter);
-                counter->active = 0;
+                counter->state = PERF_COUNTER_STATE_INACTIVE;
                 ctx->nr_active--;
                 cpuctx->active_oncpu--;
                 counter->task = NULL;
@@ -281,7 +281,7 @@ static void __perf_install_in_context(void *info)
 
         if (cpuctx->active_oncpu < perf_max_counters) {
                 counter->hw_ops->hw_perf_counter_enable(counter);
-                counter->active = 1;
+                counter->state = PERF_COUNTER_STATE_ACTIVE;
                 counter->oncpu = cpu;
                 ctx->nr_active++;
                 cpuctx->active_oncpu++;
@@ -328,7 +328,6 @@ retry:
 
         spin_lock_irq(&ctx->lock);
         /*
-         * If the context is active and the counter has not been added
          * we need to retry the smp call.
          */
         if (ctx->nr_active && list_empty(&counter->list_entry)) {
@@ -353,12 +352,12 @@ counter_sched_out(struct perf_counter *counter,
                   struct perf_cpu_context *cpuctx,
                   struct perf_counter_context *ctx)
 {
-        if (!counter->active)
+        if (counter->state != PERF_COUNTER_STATE_ACTIVE)
                 return;
 
         counter->hw_ops->hw_perf_counter_disable(counter);
-        counter->active =  0;
-        counter->oncpu  = -1;
+        counter->state = PERF_COUNTER_STATE_INACTIVE;
+        counter->oncpu = -1;
 
         cpuctx->active_oncpu--;
         ctx->nr_active--;
@@ -415,11 +414,11 @@ counter_sched_in(struct perf_counter *counter,
                  struct perf_counter_context *ctx,
                  int cpu)
 {
-        if (counter->active == -1)
+        if (counter->state == PERF_COUNTER_STATE_OFF)
                 return;
 
         counter->hw_ops->hw_perf_counter_enable(counter);
-        counter->active = 1;
+        counter->state = PERF_COUNTER_STATE_ACTIVE;
         counter->oncpu = cpu;   /* TODO: put 'cpu' into cpuctx->cpu */
 
         cpuctx->active_oncpu++;
@@ -506,8 +505,8 @@ int perf_counter_task_disable(void)
         perf_flags = hw_perf_save_disable();
 
         list_for_each_entry(counter, &ctx->counter_list, list_entry) {
-                WARN_ON_ONCE(counter->active == 1);
-                counter->active = -1;
+                WARN_ON_ONCE(counter->state == PERF_COUNTER_STATE_ACTIVE);
+                counter->state = PERF_COUNTER_STATE_OFF;
         }
         hw_perf_restore(perf_flags);
 
@@ -540,9 +539,9 @@ int perf_counter_task_enable(void)
         perf_flags = hw_perf_save_disable();
 
         list_for_each_entry(counter, &ctx->counter_list, list_entry) {
-                if (counter->active != -1)
+                if (counter->state != PERF_COUNTER_STATE_OFF)
                         continue;
-                counter->active = 0;
+                counter->state = PERF_COUNTER_STATE_INACTIVE;
         }
         hw_perf_restore(perf_flags);
 
@@ -620,7 +619,7 @@ static u64 perf_counter_read(struct perf_counter *counter)
          * If counter is enabled and currently active on a CPU, update the
          * value in the counter structure:
          */
-        if (counter->active) {
+        if (counter->state == PERF_COUNTER_STATE_ACTIVE) {
                 smp_call_function_single(counter->oncpu,
                                          __hw_perf_counter_read, counter, 1);
         }
@@ -673,7 +672,7 @@ static struct perf_data *perf_switch_irq_data(struct perf_counter *counter)
 
 retry:
         spin_lock_irq(&ctx->lock);
-        if (!counter->active) {
+        if (counter->state != PERF_COUNTER_STATE_ACTIVE) {
                 counter->irqdata = counter->usrdata;
                 counter->usrdata = oldirqdata;
                 spin_unlock_irq(&ctx->lock);