1 files changed, 100 insertions, 10 deletions

diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
index 01861eebed79..3a44dd1e33d2 100644
--- a/include/linux/percpu_counter.h
+++ b/include/linux/percpu_counter.h
@@ -13,7 +13,9 @@
 #include <linux/threads.h>
 #include <linux/percpu.h>
 #include <linux/types.h>
-#include <linux/gfp.h>
+
+/* percpu_counter batch for local add or sub */
+#define PERCPU_COUNTER_LOCAL_BATCH	INT_MAX
 
 #ifdef CONFIG_SMP
 
@@ -28,22 +30,35 @@ struct percpu_counter {
 
 extern int percpu_counter_batch;
 
-int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp,
-			  struct lock_class_key *key);
+int __percpu_counter_init_many(struct percpu_counter *fbc, s64 amount,
+			       gfp_t gfp, u32 nr_counters,
+			       struct lock_class_key *key);
 
-#define percpu_counter_init(fbc, value, gfp)				\
+#define percpu_counter_init_many(fbc, value, gfp, nr_counters)		\
 	({								\
 		static struct lock_class_key __key;			\
 									\
-		__percpu_counter_init(fbc, value, gfp, &__key);		\
+		__percpu_counter_init_many(fbc, value, gfp, nr_counters,\
+					   &__key);			\
 	})
 
-void percpu_counter_destroy(struct percpu_counter *fbc);
+
+#define percpu_counter_init(fbc, value, gfp)				\
+	percpu_counter_init_many(fbc, value, gfp, 1)
+
+void percpu_counter_destroy_many(struct percpu_counter *fbc, u32 nr_counters);
+static inline void percpu_counter_destroy(struct percpu_counter *fbc)
+{
+	percpu_counter_destroy_many(fbc, 1);
+}
+
 void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
 void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount,
 			      s32 batch);
 s64 __percpu_counter_sum(struct percpu_counter *fbc);
 int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch);
+bool __percpu_counter_limited_add(struct percpu_counter *fbc, s64 limit,
+				  s64 amount, s32 batch);
 void percpu_counter_sync(struct percpu_counter *fbc);
 
 static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
@@ -56,6 +71,29 @@ static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
 	percpu_counter_add_batch(fbc, amount, percpu_counter_batch);
 }
 
+static inline bool
+percpu_counter_limited_add(struct percpu_counter *fbc, s64 limit, s64 amount)
+{
+	return __percpu_counter_limited_add(fbc, limit, amount,
+					    percpu_counter_batch);
+}
+
+/*
+ * With percpu_counter_add_local() and percpu_counter_sub_local(), counts
+ * are accumulated in local per cpu counter and not in fbc->count until
+ * local count overflows PERCPU_COUNTER_LOCAL_BATCH. This makes counter
+ * write efficient.
+ * But percpu_counter_sum(), instead of percpu_counter_read(), needs to be
+ * used to add up the counts from each CPU to account for all the local
+ * counts. So percpu_counter_add_local() and percpu_counter_sub_local()
+ * should be used when a counter is updated frequently and read rarely.
+ */
+static inline void
+percpu_counter_add_local(struct percpu_counter *fbc, s64 amount)
+{
+	percpu_counter_add_batch(fbc, amount, PERCPU_COUNTER_LOCAL_BATCH);
+}
+
 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
 {
 	s64 ret = __percpu_counter_sum(fbc);
@@ -98,11 +136,27 @@ struct percpu_counter {
 	s64 count;
 };
 
+static inline int percpu_counter_init_many(struct percpu_counter *fbc,
+					   s64 amount, gfp_t gfp,
+					   u32 nr_counters)
+{
+	u32 i;
+
+	for (i = 0; i < nr_counters; i++)
+		fbc[i].count = amount;
+
+	return 0;
+}
+
 static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount,
 				      gfp_t gfp)
 {
-	fbc->count = amount;
-	return 0;
+	return percpu_counter_init_many(fbc, amount, gfp, 1);
+}
+
+static inline void percpu_counter_destroy_many(struct percpu_counter *fbc,
+					       u32 nr_counters)
+{
 }
 
 static inline void percpu_counter_destroy(struct percpu_counter *fbc)
@@ -133,9 +187,39 @@ __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch)
 static inline void
 percpu_counter_add(struct percpu_counter *fbc, s64 amount)
 {
-	preempt_disable();
+	unsigned long flags;
+
+	local_irq_save(flags);
 	fbc->count += amount;
-	preempt_enable();
+	local_irq_restore(flags);
+}
+
+static inline bool
+percpu_counter_limited_add(struct percpu_counter *fbc, s64 limit, s64 amount)
+{
+	unsigned long flags;
+	bool good = false;
+	s64 count;
+
+	if (amount == 0)
+		return true;
+
+	local_irq_save(flags);
+	count = fbc->count + amount;
+	if ((amount > 0 && count <= limit) ||
+	    (amount < 0 && count >= limit)) {
+		fbc->count = count;
+		good = true;
+	}
+	local_irq_restore(flags);
+	return good;
+}
+
+/* non-SMP percpu_counter_add_local is the same with percpu_counter_add */
+static inline void
+percpu_counter_add_local(struct percpu_counter *fbc, s64 amount)
+{
+	percpu_counter_add(fbc, amount);
 }
 
 static inline void
@@ -193,4 +277,10 @@ static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
 	percpu_counter_add(fbc, -amount);
 }
 
+static inline void
+percpu_counter_sub_local(struct percpu_counter *fbc, s64 amount)
+{
+	percpu_counter_add_local(fbc, -amount);
+}
+
 #endif /* _LINUX_PERCPU_COUNTER_H */