1 files changed, 60 insertions, 0 deletions

diff --git a/include/linux/percpu_ida.h b/include/linux/percpu_ida.h
new file mode 100644
index 000000000000..0b23edbee309
--- /dev/null
+++ b/include/linux/percpu_ida.h
@@ -0,0 +1,60 @@
+#ifndef __PERCPU_IDA_H__
+#define __PERCPU_IDA_H__
+
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <linux/init.h>
+#include <linux/spinlock_types.h>
+#include <linux/wait.h>
+#include <linux/cpumask.h>
+
+struct percpu_ida_cpu;
+
+struct percpu_ida {
+        /*
+         * number of tags available to be allocated, as passed to
+         * percpu_ida_init()
+         */
+        unsigned                        nr_tags;
+
+        struct percpu_ida_cpu __percpu  *tag_cpu;
+
+        /*
+         * Bitmap of cpus that (may) have tags on their percpu freelists:
+         * steal_tags() uses this to decide when to steal tags, and which cpus
+         * to try stealing from.
+         *
+         * It's ok for a freelist to be empty when its bit is set - steal_tags()
+         * will just keep looking - but the bitmap _must_ be set whenever a
+         * percpu freelist does have tags.
+         */
+        cpumask_t                       cpus_have_tags;
+
+        struct {
+                spinlock_t              lock;
+                /*
+                 * When we go to steal tags from another cpu (see steal_tags()),
+                 * we want to pick a cpu at random. Cycling through them every
+                 * time we steal is a bit easier and more or less equivalent:
+                 */
+                unsigned                cpu_last_stolen;
+
+                /* For sleeping on allocation failure */
+                wait_queue_head_t       wait;
+
+                /*
+                 * Global freelist - it's a stack where nr_free points to the
+                 * top
+                 */
+                unsigned                nr_free;
+                unsigned                *freelist;
+        } ____cacheline_aligned_in_smp;
+};
+
+int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp);
+void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
+
+void percpu_ida_destroy(struct percpu_ida *pool);
+int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags);
+
+#endif /* __PERCPU_IDA_H__ */