bpf, net: xskmap memory usage

A new helper is introduced to calculate xskmap memory usage.

The xfsmap memory usage can be dynamically changed when we add or remove
a xsk_map_node. Hence we need to track the count of xsk_map_node to get
its memory usage.

The result as follows,
- before
10: xskmap  name count_map  flags 0x0
        key 4B  value 4B  max_entries 65536  memlock 524288B

- after
10: xskmap  name count_map  flags 0x0 <<< no elements case
        key 4B  value 4B  max_entries 65536  memlock 524608B

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230305124615.12358-17-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 3057e1a4a11c..e96a1151ec75 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -38,6 +38,7 @@ struct xdp_umem {
 struct xsk_map {
 	struct bpf_map map;
 	spinlock_t lock; /* Synchronize map updates */
+	atomic_t count;
 	struct xdp_sock __rcu *xsk_map[];
 };