1 files changed, 74 insertions, 20 deletions

diff --git a/lib/percpu_ida.c b/lib/percpu_ida.c
index bab1ba2a4c71..9d054bf91d0f 100644
--- a/lib/percpu_ida.c
+++ b/lib/percpu_ida.c
@@ -30,15 +30,6 @@
 #include <linux/spinlock.h>
 #include <linux/percpu_ida.h>
 
-/*
- * Number of tags we move between the percpu freelist and the global freelist at
- * a time
- */
-#define IDA_PCPU_BATCH_MOVE     32U
-
-/* Max size of percpu freelist, */
-#define IDA_PCPU_SIZE           ((IDA_PCPU_BATCH_MOVE * 3) / 2)
-
 struct percpu_ida_cpu {
         /*
          * Even though this is percpu, we need a lock for tag stealing by remote
@@ -78,7 +69,7 @@ static inline void steal_tags(struct percpu_ida *pool,
         struct percpu_ida_cpu *remote;
 
         for (cpus_have_tags = cpumask_weight(&pool->cpus_have_tags);
-             cpus_have_tags * IDA_PCPU_SIZE > pool->nr_tags / 2;
+             cpus_have_tags * pool->percpu_max_size > pool->nr_tags / 2;
              cpus_have_tags--) {
                 cpu = cpumask_next(cpu, &pool->cpus_have_tags);
 
@@ -123,11 +114,10 @@ static inline void alloc_global_tags(struct percpu_ida *pool,
 {
         move_tags(tags->freelist, &tags->nr_free,
                   pool->freelist, &pool->nr_free,
-                  min(pool->nr_free, IDA_PCPU_BATCH_MOVE));
+                  min(pool->nr_free, pool->percpu_batch_size));
 }
 
-static inline unsigned alloc_local_tag(struct percpu_ida *pool,
-                                       struct percpu_ida_cpu *tags)
+static inline unsigned alloc_local_tag(struct percpu_ida_cpu *tags)
 {
         int tag = -ENOSPC;
 
@@ -168,7 +158,7 @@ int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp)
         tags = this_cpu_ptr(pool->tag_cpu);
 
         /* Fastpath */
-        tag = alloc_local_tag(pool, tags);
+        tag = alloc_local_tag(tags);
         if (likely(tag >= 0)) {
                 local_irq_restore(flags);
                 return tag;
@@ -245,17 +235,17 @@ void percpu_ida_free(struct percpu_ida *pool, unsigned tag)
                 wake_up(&pool->wait);
         }
 
-        if (nr_free == IDA_PCPU_SIZE) {
+        if (nr_free == pool->percpu_max_size) {
                 spin_lock(&pool->lock);
 
                 /*
                  * Global lock held and irqs disabled, don't need percpu
                  * lock
                  */
-                if (tags->nr_free == IDA_PCPU_SIZE) {
+                if (tags->nr_free == pool->percpu_max_size) {
                         move_tags(pool->freelist, &pool->nr_free,
                                   tags->freelist, &tags->nr_free,
-                                  IDA_PCPU_BATCH_MOVE);
+                                  pool->percpu_batch_size);
 
                         wake_up(&pool->wait);
                 }
@@ -292,7 +282,8 @@ EXPORT_SYMBOL_GPL(percpu_ida_destroy);
  * Allocation is percpu, but sharding is limited by nr_tags - for best
  * performance, the workload should not span more cpus than nr_tags / 128.
  */
-int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
+int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
+        unsigned long max_size, unsigned long batch_size)
 {
         unsigned i, cpu, order;
 
@@ -301,6 +292,8 @@ int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
         init_waitqueue_head(&pool->wait);
         spin_lock_init(&pool->lock);
         pool->nr_tags = nr_tags;
+        pool->percpu_max_size = max_size;
+        pool->percpu_batch_size = batch_size;
 
         /* Guard against overflow */
         if (nr_tags > (unsigned) INT_MAX + 1) {
@@ -319,7 +312,7 @@ int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
         pool->nr_free = nr_tags;
 
         pool->tag_cpu = __alloc_percpu(sizeof(struct percpu_ida_cpu) +
-                                       IDA_PCPU_SIZE * sizeof(unsigned),
+                                       pool->percpu_max_size * sizeof(unsigned),
                                        sizeof(unsigned));
         if (!pool->tag_cpu)
                 goto err;
@@ -332,4 +325,65 @@ err:
         percpu_ida_destroy(pool);
         return -ENOMEM;
 }
-EXPORT_SYMBOL_GPL(percpu_ida_init);
+EXPORT_SYMBOL_GPL(__percpu_ida_init);
+
+/**
+ * percpu_ida_for_each_free - iterate free ids of a pool
+ * @pool: pool to iterate
+ * @fn: interate callback function
+ * @data: parameter for @fn
+ *
+ * Note, this doesn't guarantee to iterate all free ids restrictly. Some free
+ * ids might be missed, some might be iterated duplicated, and some might
+ * be iterated and not free soon.
+ */
+int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
+        void *data)
+{
+        unsigned long flags;
+        struct percpu_ida_cpu *remote;
+        unsigned cpu, i, err = 0;
+
+        local_irq_save(flags);
+        for_each_possible_cpu(cpu) {
+                remote = per_cpu_ptr(pool->tag_cpu, cpu);
+                spin_lock(&remote->lock);
+                for (i = 0; i < remote->nr_free; i++) {
+                        err = fn(remote->freelist[i], data);
+                        if (err)
+                                break;
+                }
+                spin_unlock(&remote->lock);
+                if (err)
+                        goto out;
+        }
+
+        spin_lock(&pool->lock);
+        for (i = 0; i < pool->nr_free; i++) {
+                err = fn(pool->freelist[i], data);
+                if (err)
+                        break;
+        }
+        spin_unlock(&pool->lock);
+out:
+        local_irq_restore(flags);
+        return err;
+}
+EXPORT_SYMBOL_GPL(percpu_ida_for_each_free);
+
+/**
+ * percpu_ida_free_tags - return free tags number of a specific cpu or global pool
+ * @pool: pool related
+ * @cpu: specific cpu or global pool if @cpu == nr_cpu_ids
+ *
+ * Note: this just returns a snapshot of free tags number.
+ */
+unsigned percpu_ida_free_tags(struct percpu_ida *pool, int cpu)
+{
+        struct percpu_ida_cpu *remote;
+        if (cpu == nr_cpu_ids)
+                return pool->nr_free;
+        remote = per_cpu_ptr(pool->tag_cpu, cpu);
+        return remote->nr_free;
+}
+EXPORT_SYMBOL_GPL(percpu_ida_free_tags);