From 8fdf5b780a148c4a7490c211acad3c01b4dde6ac Mon Sep 17 00:00:00 2001 From: "Daniel T. Lee" Date: Tue, 8 Oct 2019 02:21:17 +0900 Subject: samples: bpf: Add max_pckt_size option at xdp_adjust_tail Currently, at xdp_adjust_tail_kern.c, MAX_PCKT_SIZE is limited to 600. To make this size flexible, static global variable 'max_pcktsz' is added. By updating new packet size from the user space, xdp_adjust_tail_kern.o will use this value as a new max packet size. This static global variable can be accesible from .data section with bpf_object__find_map* from user space, since it is considered as internal map (accessible with .bss/.data/.rodata suffix). If no '-P ' option is used, the size of maximum packet will be 600 as a default. For clarity, change the helper to fetch map from 'bpf_map__next' to 'bpf_object__find_map_fd_by_name'. Also, changed the way to test prog_fd, map_fd from '!= 0' to '< 0', since fd could be 0 when stdin is closed. Signed-off-by: Daniel T. Lee Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20191007172117.3916-1-danieltimlee@gmail.com --- samples/bpf/xdp_adjust_tail_user.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) (limited to 'samples/bpf/xdp_adjust_tail_user.c') diff --git a/samples/bpf/xdp_adjust_tail_user.c b/samples/bpf/xdp_adjust_tail_user.c index a3596b617c4c..d86e9ad0356b 100644 --- a/samples/bpf/xdp_adjust_tail_user.c +++ b/samples/bpf/xdp_adjust_tail_user.c @@ -23,6 +23,7 @@ #include "libbpf.h" #define STATS_INTERVAL_S 2U +#define MAX_PCKT_SIZE 600 static int ifindex = -1; static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST; @@ -72,6 +73,7 @@ static void usage(const char *cmd) printf("Usage: %s [...]\n", cmd); printf(" -i Interface\n"); printf(" -T Default: 0 (forever)\n"); + printf(" -P Default: %u\n", MAX_PCKT_SIZE); printf(" -S use skb-mode\n"); printf(" -N enforce native mode\n"); printf(" -F force loading prog\n"); @@ -85,13 +87,14 @@ int main(int argc, char **argv) .prog_type = BPF_PROG_TYPE_XDP, }; unsigned char opt_flags[256] = {}; - const char *optstr = "i:T:SNFh"; + const char *optstr = "i:T:P:SNFh"; struct bpf_prog_info info = {}; __u32 info_len = sizeof(info); unsigned int kill_after_s = 0; int i, prog_fd, map_fd, opt; struct bpf_object *obj; - struct bpf_map *map; + __u32 max_pckt_size = 0; + __u32 key = 0; char filename[256]; int err; @@ -110,6 +113,9 @@ int main(int argc, char **argv) case 'T': kill_after_s = atoi(optarg); break; + case 'P': + max_pckt_size = atoi(optarg); + break; case 'S': xdp_flags |= XDP_FLAGS_SKB_MODE; break; @@ -150,15 +156,20 @@ int main(int argc, char **argv) if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd)) return 1; - map = bpf_map__next(NULL, obj); - if (!map) { - printf("finding a map in obj file failed\n"); - return 1; + /* static global var 'max_pcktsz' is accessible from .data section */ + if (max_pckt_size) { + map_fd = bpf_object__find_map_fd_by_name(obj, "xdp_adju.data"); + if (map_fd < 0) { + printf("finding a max_pcktsz map in obj file failed\n"); + return 1; + } + bpf_map_update_elem(map_fd, &key, &max_pckt_size, BPF_ANY); } - map_fd = bpf_map__fd(map); - if (!prog_fd) { - printf("load_bpf_file: %s\n", strerror(errno)); + /* fetch icmpcnt map */ + map_fd = bpf_object__find_map_fd_by_name(obj, "icmpcnt"); + if (map_fd < 0) { + printf("finding a icmpcnt map in obj file failed\n"); return 1; } -- cgit v1.2.3