Merge branch 'bpf-lru'

Martin KaFai Lau says:

====================
bpf: LRU map

This patch set adds LRU map implementation to the existing BPF map
family.

The first few patches introduce the basic BPF LRU list
implementation.

The later patches introduce the LRU versions of the
existing BPF_MAP_TYPE_LRU_[PERCPU_]HASH maps by leveraging
the BPF LRU list.

v2:
- Added a percpu LRU list option which can be specified as
  a map attribute.

  [Note: percpu LRU list has nothing to do with the map's value]

- Removed the cpu variable from the struct bpf_lru_locallist
  since it is not needed.

- Changed the __bpf_lru_node_move_out to __bpf_lru_node_move_to_free in
  patch 1 to prepare the percpu LRU list in patch 2.

- Moved the test_lru_map under selftests

- Refactored a few things in the test codes
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

Author: davem330

include/uapi/linux/bpf.h

@@ -85,6 +85,8 @@ enum bpf_map_type {
 	BPF_MAP_TYPE_PERCPU_ARRAY,
 	BPF_MAP_TYPE_STACK_TRACE,
 	BPF_MAP_TYPE_CGROUP_ARRAY,
+	BPF_MAP_TYPE_LRU_HASH,
+	BPF_MAP_TYPE_LRU_PERCPU_HASH,
 };
 
 enum bpf_prog_type {
@@ -106,6 +108,13 @@ enum bpf_prog_type {
 #define BPF_EXIST	2 /* update existing element */
 
 #define BPF_F_NO_PREALLOC	(1U << 0)
+/* Instead of having one common LRU list in the
+ * BPF_MAP_TYPE_LRU_[PERCPU_]HASH map, use a percpu LRU list
+ * which can scale and perform better.
+ * Note, the LRU nodes (including free nodes) cannot be moved
+ * across different LRU lists.
+ */
+#define BPF_F_NO_COMMON_LRU	(1U << 1)
 
 union bpf_attr {
 	struct { /* anonymous struct used by BPF_MAP_CREATE command */

kernel/bpf/Makefile

@@ -1,7 +1,7 @@
 obj-y := core.o
 
 obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o
-obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o
+obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o
 ifeq ($(CONFIG_PERF_EVENTS),y)
 obj-$(CONFIG_BPF_SYSCALL) += stackmap.o
 endif