[PATCH bpf-next] bpf: make bpf_link_info.iter similar to bpf_iter_link_info

bpf_link_info.iter is used by link_query to return
bpf_iter_link_info to user space. Fields may be different
,e.g., map_fd vs. map_id, so we cannot reuse
the exact structure. But make them similar, e.g.,
  struct bpf_link_info {
     /* common fields */
     union {
	struct { ... } raw_tracepoint;
	struct { ... } tracing;
	...
	struct {
	    /* common fields for iter */
	    union {
		struct {
		    __u32 map_id;
		} map;
		/* other structs for other targets */
	    };
	};
    };
 };
so the structure is extensible the same way as
bpf_iter_link_info.

Fixes: 6b0a249a301e ("bpf: Implement link_query for bpf iterators")
Acked-by: Andrii Nakryiko <redacted>
Signed-off-by: Yonghong Song <redacted>
---
 include/uapi/linux/bpf.h       | 6 ++++--
 tools/include/uapi/linux/bpf.h | 6 ++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

This patch was the first patch in
  https://lore.kernel.org/bpf/20200827000618.2711826-1-yhs@fb.com/
I now sent this separately as it is largely independent and my
immediate follow-ups does not depend on this any more.

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 0388bc0200b0..ef7af384f5ee 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h

@@ -4251,8 +4251,10 @@ struct bpf_link_info {
 			__aligned_u64 target_name; /* in/out: target_name buffer ptr */
 			__u32 target_name_len;	   /* in/out: target_name buffer len */
 			union {
-				__u32 map_id;
-			} map;
+				struct {
+					__u32 map_id;
+				} map;
+			};
 		} iter;
 		struct  {
 			__u32 netns_ino;

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 0388bc0200b0..ef7af384f5ee 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h

@@ -4251,8 +4251,10 @@ struct bpf_link_info {
 			__aligned_u64 target_name; /* in/out: target_name buffer ptr */
 			__u32 target_name_len;	   /* in/out: target_name buffer len */
 			union {
-				__u32 map_id;
-			} map;
+				struct {
+					__u32 map_id;
+				} map;
+			};
 		} iter;
 		struct  {
 			__u32 netns_ino;

-- 
2.24.1

On 8/28/20 7:19 AM, Yonghong Song wrote:

bpf_link_info.iter is used by link_query to return
bpf_iter_link_info to user space. Fields may be different
,e.g., map_fd vs. map_id, so we cannot reuse
the exact structure. But make them similar, e.g.,
   struct bpf_link_info {
      /* common fields */
      union {
	struct { ... } raw_tracepoint;
	struct { ... } tracing;
	...
	struct {
	    /* common fields for iter */
	    union {
		struct {
		    __u32 map_id;
		} map;
		/* other structs for other targets */
	    };
	};
     };
  };
so the structure is extensible the same way as
bpf_iter_link_info.

Fixes: 6b0a249a301e ("bpf: Implement link_query for bpf iterators")
Acked-by: Andrii Nakryiko <redacted>
Signed-off-by: Yonghong Song <redacted>

Applied, thanks!