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bpftool: Fix missing BTF output for json during map dump

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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: 99f9863a0c ("bpftool: Match maps by name")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Cc: Paul Chaignon <paul.chaignon@orange.com>
Link: https://lore.kernel.org/bpf/20200115230025.1101828-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau 2020-01-15 15:00:25 -08:00 committed by Alexei Starovoitov
parent d7de72674a
commit 188a486619
1 changed files with 21 additions and 23 deletions
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44
tools/bpf/bpftool/map.c
View file

@ -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 (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++)