libbpf: Forward-declare bpf_stats_type for systems with outdated UAPI headers

Systems that doesn't yet have the very latest linux/bpf.h header, enum
bpf_stats_type will be undefined, causing compilation warnings. Prevents this
by forward-declaring enum.

Fixes: 5470715c0f9c ("libbpf: Add support for command BPF_ENABLE_STATS")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200621031159.2279101-1-andriin@fb.com

diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 1b6015b21ba85979bdbf792cca6ef43319ae9b3f..dbef24ebcfcb9d251d5d6fa07e9f1d55d4bcbc82 100644 (file)
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -233,6 +233,8 @@ LIBBPF_API int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf,
 LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
                                 __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
                                 __u64 *probe_offset, __u64 *probe_addr);
+
+enum bpf_stats_type; /* defined in up-to-date linux/bpf.h */
 LIBBPF_API int bpf_enable_stats(enum bpf_stats_type type);
 
 #ifdef __cplusplus