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Commit 74f312ef authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Daniel Borkmann
Browse files

bpftool: add pop and dequeue commands 



This is intended to be used with queues and stacks, it pops and prints
the last element via bpf_map_lookup_and_delete_elem.

Example:

bpftool map create /sys/fs/bpf/q type queue value 4 entries 10 name q
bpftool map push pinned /sys/fs/bpf/q value 0 1 2 3
bpftool map pop pinned /sys/fs/bpf/q
value: 00 01 02 03
bpftool map pop pinned /sys/fs/bpf/q
Error: empty map

bpftool map create /sys/fs/bpf/s type stack value 4 entries 10 name s
bpftool map enqueue pinned /sys/fs/bpf/s value 0 1 2 3
bpftool map dequeue pinned /sys/fs/bpf/s
value: 00 01 02 03
bpftool map dequeue pinned /sys/fs/bpf/s
Error: empty map

Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 549d4d3d

tools/bpf/bpftool/Documentation/bpftool-map.rst

+8 −0
Original line number Diff line number Diff line
@@ -33,7 +33,9 @@ MAP COMMANDS 
|	**bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*]

|	**bpftool** **map peek**       *MAP*

|	**bpftool** **map push**       *MAP* **value** *VALUE*

|	**bpftool** **map pop**        *MAP*

|	**bpftool** **map enqueue**    *MAP* **value** *VALUE*

|	**bpftool** **map dequeue**    *MAP*

|	**bpftool** **map help**

|

|	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
@@ -116,9 +118,15 @@ DESCRIPTION 
	**bpftool map push**  *MAP* **value** *VALUE*

		  Push **value** onto the stack.



	**bpftool map pop**  *MAP*

		  Pop and print **value** from the stack.



	**bpftool map enqueue**  *MAP* **value** *VALUE*

		  Enqueue **value** into the queue.



	**bpftool map dequeue**  *MAP*

		  Dequeue and print **value** from the queue.



	**bpftool map help**

		  Print short help message.

tools/bpf/bpftool/map.c

+90 −35
Original line number Diff line number Diff line
@@ -857,12 +857,51 @@ static int do_update(int argc, char **argv) 
	return err;

}



static void print_key_value(struct bpf_map_info *info, void *key,

			    void *value)

{

	json_writer_t *btf_wtr;

	struct btf *btf = NULL;

	int err;



	err = btf__get_from_id(info->btf_id, &btf);

	if (err) {

		p_err("failed to get btf");

		return;

	}



	if (json_output) {

		print_entry_json(info, key, value, btf);

	} else if (btf) {

		/* if here json_wtr wouldn't have been initialised,

		 * so let's create separate writer for btf

		 */

		btf_wtr = get_btf_writer();

		if (!btf_wtr) {

			p_info("failed to create json writer for btf. falling back to plain output");

			btf__free(btf);

			btf = NULL;

			print_entry_plain(info, key, value);

		} else {

			struct btf_dumper d = {

				.btf = btf,

				.jw = btf_wtr,

				.is_plain_text = true,

			};



			do_dump_btf(&d, info, key, value);

			jsonw_destroy(&btf_wtr);

		}

	} else {

		print_entry_plain(info, key, value);

	}

	btf__free(btf);

}



static int do_lookup(int argc, char **argv)

{

	struct bpf_map_info info = {};

	__u32 len = sizeof(info);

	json_writer_t *btf_wtr;

	struct btf *btf = NULL;

	void *key, *value;

	int err;

	int fd;
@@ -900,43 +939,12 @@ static int do_lookup(int argc, char **argv) 
	}



	/* here means bpf_map_lookup_elem() succeeded */

	err = btf__get_from_id(info.btf_id, &btf);

	if (err) {

		p_err("failed to get btf");

		goto exit_free;

	}



	if (json_output) {

		print_entry_json(&info, key, value, btf);

	} else if (btf) {

		/* if here json_wtr wouldn't have been initialised,

		 * so let's create separate writer for btf

		 */

		btf_wtr = get_btf_writer();

		if (!btf_wtr) {

			p_info("failed to create json writer for btf. falling back to plain output");

			btf__free(btf);

			btf = NULL;

			print_entry_plain(&info, key, value);

		} else {

			struct btf_dumper d = {

				.btf = btf,

				.jw = btf_wtr,

				.is_plain_text = true,

			};



			do_dump_btf(&d, &info, key, value);

			jsonw_destroy(&btf_wtr);

		}

	} else {

		print_entry_plain(&info, key, value);

	}

	print_key_value(&info, key, value);



exit_free:

	free(key);

	free(value);

	close(fd);

	btf__free(btf);



	return err;

}
@@ -1149,6 +1157,49 @@ static int do_create(int argc, char **argv) 
	return 0;

}



static int do_pop_dequeue(int argc, char **argv)

{

	struct bpf_map_info info = {};

	__u32 len = sizeof(info);

	void *key, *value;

	int err;

	int fd;



	if (argc < 2)

		usage();



	fd = map_parse_fd_and_info(&argc, &argv, &info, &len);

	if (fd < 0)

		return -1;



	err = alloc_key_value(&info, &key, &value);

	if (err)

		goto exit_free;



	err = bpf_map_lookup_and_delete_elem(fd, key, value);

	if (err) {

		if (errno == ENOENT) {

			if (json_output)

				jsonw_null(json_wtr);

			else

				printf("Error: empty map\n");

		} else {

			p_err("pop failed: %s", strerror(errno));

		}



		goto exit_free;

	}



	print_key_value(&info, key, value);



exit_free:

	free(key);

	free(value);

	close(fd);



	return err;

}



static int do_help(int argc, char **argv)

{

	if (json_output) {
@@ -1170,7 +1221,9 @@ static int do_help(int argc, char **argv) 
		"       %s %s event_pipe MAP [cpu N index M]\n"

		"       %s %s peek       MAP\n"

		"       %s %s push       MAP value VALUE\n"

		"       %s %s pop        MAP\n"

		"       %s %s enqueue    MAP value VALUE\n"

		"       %s %s dequeue    MAP\n"

		"       %s %s help\n"

		"\n"

		"       " HELP_SPEC_MAP "\n"
@@ -1189,7 +1242,7 @@ static int do_help(int argc, char **argv) 
		bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2],

		bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2],

		bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2],

		bin_name, argv[-2]);

		bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2]);



	return 0;

}
@@ -1209,6 +1262,8 @@ static const struct cmd cmds[] = { 
	{ "peek",	do_lookup },

	{ "push",	do_update },

	{ "enqueue",	do_update },

	{ "pop",	do_pop_dequeue },

	{ "dequeue",	do_pop_dequeue },

	{ 0 }

};