bpf: avoid false sharing of map refcount with max_entries

[android-x86/kernel.git] / include / linux / bpf.h

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 0bcf803..5c5be80 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -42,7 +42,14 @@ struct bpf_map_ops {
 };
 
 struct bpf_map {
-       atomic_t refcnt;
+       /* 1st cacheline with read-mostly members of which some
+        * are also accessed in fast-path (e.g. ops, max_entries).
+        */
+       const struct bpf_map_ops *ops ____cacheline_aligned;
+       struct bpf_map *inner_map_meta;
+#ifdef CONFIG_SECURITY
+       void *security;
+#endif
        enum bpf_map_type map_type;
        u32 key_size;
        u32 value_size;
@@ -52,11 +59,15 @@ struct bpf_map {
        u32 id;
        int numa_node;
        bool unpriv_array;
-       struct user_struct *user;
-       const struct bpf_map_ops *ops;
-       struct work_struct work;
+       /* 7 bytes hole */
+
+       /* 2nd cacheline with misc members to avoid false sharing
+        * particularly with refcounting.
+        */
+       struct user_struct *user ____cacheline_aligned;
+       atomic_t refcnt;
        atomic_t usercnt;
-       struct bpf_map *inner_map_meta;
+       struct work_struct work;
 };
 
 /* function argument constraints */