diff mbox series

[v3,bpf-next,2/5] bpftool: Fix missing BTF output for json during map dump

Message ID 20200115230025.1101828-1-kafai@fb.com
State Accepted
Delegated to: BPF Maintainers
Headers show
Series bpftool: Support dumping a map with btf_vmlinux_value_type_id | expand

Commit Message

Martin KaFai Lau Jan. 15, 2020, 11 p.m. UTC
The btf availability check is only done for plain text output.
It causes the whole BTF output went missing when json_output
is used.

This patch simplifies the logic a little by avoiding passing "int btf" to
map_dump().

For plain text output, the btf_wtr is only created when the map has
BTF (i.e. info->btf_id != 0).  The nullness of "json_writer_t *wtr"
in map_dump() alone can decide if dumping BTF output is needed.
As long as wtr is not NULL, map_dump() will print out the BTF-described
data whenever a map has BTF available (i.e. info->btf_id != 0)
regardless of json or plain-text output.

In do_dump(), the "int btf" is also renamed to "int do_plain_btf".

Fixes: 99f9863a0c45 ("bpftool: Match maps by name")
Cc: Paul Chaignon <paul.chaignon@orange.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 tools/bpf/bpftool/map.c | 42 ++++++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 22 deletions(-)
diff mbox series

Patch

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index e00e9e19d6b7..45c1eda6512c 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -933,7 +933,7 @@  static int maps_have_btf(int *fds, int nb_fds)
 
 static int
 map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
-	 bool enable_btf, bool show_header)
+	 bool show_header)
 {
 	void *key, *value, *prev_key;
 	unsigned int num_elems = 0;
@@ -950,18 +950,16 @@  map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
 
 	prev_key = NULL;
 
-	if (enable_btf) {
-		err = btf__get_from_id(info->btf_id, &btf);
-		if (err || !btf) {
-			/* enable_btf is true only if we've already checked
-			 * that all maps have BTF information.
-			 */
-			p_err("failed to get btf");
-			goto exit_free;
+	if (wtr) {
+		if (info->btf_id) {
+			err = btf__get_from_id(info->btf_id, &btf);
+			if (err || !btf) {
+				err = err ? : -ESRCH;
+				p_err("failed to get btf");
+				goto exit_free;
+			}
 		}
-	}
 
-	if (wtr) {
 		if (show_header) {
 			jsonw_start_object(wtr);	/* map object */
 			show_map_header_json(info, wtr);
@@ -1009,7 +1007,7 @@  static int do_dump(int argc, char **argv)
 {
 	json_writer_t *wtr = NULL, *btf_wtr = NULL;
 	struct bpf_map_info info = {};
-	int nb_fds, i = 0, btf = 0;
+	int nb_fds, i = 0;
 	__u32 len = sizeof(info);
 	int *fds = NULL;
 	int err = -1;
@@ -1029,17 +1027,17 @@  static int do_dump(int argc, char **argv)
 	if (json_output) {
 		wtr = json_wtr;
 	} else {
-		btf = maps_have_btf(fds, nb_fds);
-		if (btf < 0)
+		int do_plain_btf;
+
+		do_plain_btf = maps_have_btf(fds, nb_fds);
+		if (do_plain_btf < 0)
 			goto exit_close;
-		if (btf) {
+
+		if (do_plain_btf) {
 			btf_wtr = get_btf_writer();
-			if (btf_wtr) {
-				wtr = btf_wtr;
-			} else {
+			wtr = btf_wtr;
+			if (!btf_wtr)
 				p_info("failed to create json writer for btf. falling back to plain output");
-				btf = 0;
-			}
 		}
 	}
 
@@ -1050,7 +1048,7 @@  static int do_dump(int argc, char **argv)
 			p_err("can't get map info: %s", strerror(errno));
 			break;
 		}
-		err = map_dump(fds[i], &info, wtr, btf, nb_fds > 1);
+		err = map_dump(fds[i], &info, wtr, nb_fds > 1);
 		if (!wtr && i != nb_fds - 1)
 			printf("\n");
 
@@ -1061,7 +1059,7 @@  static int do_dump(int argc, char **argv)
 	if (wtr && nb_fds > 1)
 		jsonw_end_array(wtr);	/* root array */
 
-	if (btf)
+	if (btf_wtr)
 		jsonw_destroy(&btf_wtr);
 exit_close:
 	for (; i < nb_fds; i++)