[RFC net-next PATCH 1/5] samples/bpf: xdp_tx_iptunnel make use of map_data[]

[Jesper Dangaard Brouer]

There is no reason to use a compile time constant MAX_IPTNL_ENTRIES
shared between the _user.c and _kern.c, when map_data[].def.max_entries
can tell us dynamically what the max_entries were of the ELF map that
the bpf loaded created.

Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com>
---
 samples/bpf/xdp_tx_iptunnel_common.h |    2 --
 samples/bpf/xdp_tx_iptunnel_kern.c   |    2 +-
 samples/bpf/xdp_tx_iptunnel_user.c   |   14 +++++++++-----
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/samples/bpf/xdp_tx_iptunnel_common.h 
b/samples/bpf/xdp_tx_iptunnel_common.h
index dd12cc35110f..b065699cacb5 100644
--- a/samples/bpf/xdp_tx_iptunnel_common.h
+++ b/samples/bpf/xdp_tx_iptunnel_common.h
@@ -9,8 +9,6 @@
 
 #include <linux/types.h>
 
-#define MAX_IPTNL_ENTRIES 256U
-
 struct vip {
        union {
                __u32 v6[4];
diff --git a/samples/bpf/xdp_tx_iptunnel_kern.c 
b/samples/bpf/xdp_tx_iptunnel_kern.c
index 0f4f6e8c8611..b19489eb3c22 100644
--- a/samples/bpf/xdp_tx_iptunnel_kern.c
+++ b/samples/bpf/xdp_tx_iptunnel_kern.c
@@ -30,7 +30,7 @@ struct bpf_map_def SEC("maps") vip2tnl = {
        .type = BPF_MAP_TYPE_HASH,
        .key_size = sizeof(struct vip),
        .value_size = sizeof(struct iptnl_info),
-       .max_entries = MAX_IPTNL_ENTRIES,
+       .max_entries = 256,
 };
 
 static __always_inline void count_tx(u32 protocol)
diff --git a/samples/bpf/xdp_tx_iptunnel_user.c 
b/samples/bpf/xdp_tx_iptunnel_user.c
index 92b8bde9337c..0500a5cc75c4 100644
--- a/samples/bpf/xdp_tx_iptunnel_user.c
+++ b/samples/bpf/xdp_tx_iptunnel_user.c
@@ -123,11 +123,6 @@ static int parse_ports(const char *port_str, int 
*min_port, int *max_port)
                return 1;
        }
 
-       if (tmp_max_port - tmp_min_port + 1 > MAX_IPTNL_ENTRIES) {
-               fprintf(stderr, "Port range (%s) is larger than %u\n",
-                       port_str, MAX_IPTNL_ENTRIES);
-               return 1;
-       }
        *min_port = tmp_min_port;
        *max_port = tmp_max_port;
 
@@ -142,6 +137,7 @@ int main(int argc, char **argv)
        int min_port = 0, max_port = 0;
        struct iptnl_info tnl = {};
        struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
+       unsigned int entries, max_entries;
        struct vip vip = {};
        char filename[256];
        int opt;
@@ -238,6 +234,14 @@ int main(int argc, char **argv)
                return 1;
        }
 
+       entries = max_port - min_port + 1;
+       max_entries = map_data[1].def.max_entries;
+       if (entries > max_entries) {
+               fprintf(stderr, "Req port entries (%u) is larger than max %u\n",
+                       entries, max_entries);
+               return 1;
+       }
+
        signal(SIGINT, int_exit);
 
        while (min_port <= max_port) {