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Message-Id: <20200910102652.10509-2-quentin@isovalent.com>
Date: Thu, 10 Sep 2020 11:26:50 +0100
From: Quentin Monnet <quentin@...valent.com>
To: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>
Cc: bpf@...r.kernel.org, netdev@...r.kernel.org,
Andrii Nakryiko <andrii.nakryiko@...il.com>,
Quentin Monnet <quentin@...valent.com>
Subject: [PATCH bpf-next v3 1/3] tools: bpftool: clean up function to dump map entry
The function used to dump a map entry in bpftool is a bit difficult to
follow, as a consequence to earlier refactorings. There is a variable
("num_elems") which does not appear to be necessary, and the error
handling would look cleaner if moved to its own function. Let's clean it
up. No functional change.
v2:
- v1 was erroneously removing the check on fd maps in an attempt to get
support for outer map dumps. This is already working. Instead, v2
focuses on cleaning up the dump_map_elem() function, to avoid
similar confusion in the future.
Signed-off-by: Quentin Monnet <quentin@...valent.com>
---
tools/bpf/bpftool/map.c | 101 +++++++++++++++++++++-------------------
1 file changed, 52 insertions(+), 49 deletions(-)
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index bc0071228f88..c8159cb4fb1e 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -213,8 +213,9 @@ static void print_entry_json(struct bpf_map_info *info, unsigned char *key,
jsonw_end_object(json_wtr);
}
-static void print_entry_error(struct bpf_map_info *info, unsigned char *key,
- const char *error_msg)
+static void
+print_entry_error_msg(struct bpf_map_info *info, unsigned char *key,
+ const char *error_msg)
{
int msg_size = strlen(error_msg);
bool single_line, break_names;
@@ -232,6 +233,40 @@ static void print_entry_error(struct bpf_map_info *info, unsigned char *key,
printf("\n");
}
+static void
+print_entry_error(struct bpf_map_info *map_info, void *key, int lookup_errno)
+{
+ /* For prog_array maps or arrays of maps, failure to lookup the value
+ * means there is no entry for that key. Do not print an error message
+ * in that case.
+ */
+ if (map_is_map_of_maps(map_info->type) ||
+ map_is_map_of_progs(map_info->type))
+ return;
+
+ if (json_output) {
+ jsonw_start_object(json_wtr); /* entry */
+ jsonw_name(json_wtr, "key");
+ print_hex_data_json(key, map_info->key_size);
+ jsonw_name(json_wtr, "value");
+ jsonw_start_object(json_wtr); /* error */
+ jsonw_string_field(json_wtr, "error", strerror(lookup_errno));
+ jsonw_end_object(json_wtr); /* error */
+ jsonw_end_object(json_wtr); /* entry */
+ } else {
+ const char *msg = NULL;
+
+ if (lookup_errno == ENOENT)
+ msg = "<no entry>";
+ else if (lookup_errno == ENOSPC &&
+ map_info->type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY)
+ msg = "<cannot read>";
+
+ print_entry_error_msg(map_info, key,
+ msg ? : strerror(lookup_errno));
+ }
+}
+
static void print_entry_plain(struct bpf_map_info *info, unsigned char *key,
unsigned char *value)
{
@@ -713,56 +748,23 @@ static int dump_map_elem(int fd, void *key, void *value,
struct bpf_map_info *map_info, struct btf *btf,
json_writer_t *btf_wtr)
{
- int num_elems = 0;
- int lookup_errno;
-
- if (!bpf_map_lookup_elem(fd, key, value)) {
- if (json_output) {
- print_entry_json(map_info, key, value, btf);
- } else {
- if (btf) {
- struct btf_dumper d = {
- .btf = btf,
- .jw = btf_wtr,
- .is_plain_text = true,
- };
-
- do_dump_btf(&d, map_info, key, value);
- } else {
- print_entry_plain(map_info, key, value);
- }
- num_elems++;
- }
- return num_elems;
+ if (bpf_map_lookup_elem(fd, key, value)) {
+ print_entry_error(map_info, key, errno);
+ return -1;
}
- /* lookup error handling */
- lookup_errno = errno;
-
- if (map_is_map_of_maps(map_info->type) ||
- map_is_map_of_progs(map_info->type))
- return 0;
-
if (json_output) {
- jsonw_start_object(json_wtr);
- jsonw_name(json_wtr, "key");
- print_hex_data_json(key, map_info->key_size);
- jsonw_name(json_wtr, "value");
- jsonw_start_object(json_wtr);
- jsonw_string_field(json_wtr, "error", strerror(lookup_errno));
- jsonw_end_object(json_wtr);
- jsonw_end_object(json_wtr);
- } else {
- const char *msg = NULL;
-
- if (lookup_errno == ENOENT)
- msg = "<no entry>";
- else if (lookup_errno == ENOSPC &&
- map_info->type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY)
- msg = "<cannot read>";
+ print_entry_json(map_info, key, value, btf);
+ } else if (btf) {
+ struct btf_dumper d = {
+ .btf = btf,
+ .jw = btf_wtr,
+ .is_plain_text = true,
+ };
- print_entry_error(map_info, key,
- msg ? : strerror(lookup_errno));
+ do_dump_btf(&d, map_info, key, value);
+ } else {
+ print_entry_plain(map_info, key, value);
}
return 0;
@@ -873,7 +875,8 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
err = 0;
break;
}
- num_elems += dump_map_elem(fd, key, value, info, btf, wtr);
+ if (!dump_map_elem(fd, key, value, info, btf, wtr))
+ num_elems++;
prev_key = key;
}
--
2.25.1
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