Commit 188a4866 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
Browse files

bpftool: Fix missing BTF output for json during map dump 



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: 99f9863a ("bpftool: Match maps by name")
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Cc: Paul Chaignon <paul.chaignon@orange.com>
Link: https://lore.kernel.org/bpf/20200115230025.1101828-1-kafai@fb.com
parent d7de7267

tools/bpf/bpftool/map.c

+20 −22
Original line number Diff line number Diff line
@@ -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) {

	if (wtr) {

		if (info->btf_id) {

			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.

			 */

				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 {

			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++)