Re: [PATCH bpf-next v4] bpftool: Dump map id instead of value for map_of_maps types

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 4/27/23 5:03 AM, Xueming Feng wrote:
When using `bpftool map dump` with map_of_maps, it is usually
more convenient to show the inner map id instead of raw value.

We are changing the plain print behavior to show inner_map_id
instead of hex value, this would help with quick look up of
inner map with `bpftool map dump id <inner_map_id>`.
To avoid disrupting scripted behavior, we will add a new
`inner_map_id` field to json output instead of replacing value.

plain print:
```
$ bpftool map dump id 138

Without Patch:
key:
fc 00 00 00 00 00 00 00  00 00 00 00 00 00 00 05
27 16 06 00
value:
8b 00 00 00
Found 1 element

With Patch:
key:
fc 00 00 00 00 00 00 00  00 00 00 00 00 00 00 05
27 16 06 00
inner_map_id:
139
Found 1 element
```

json print:
```
$ bpftool -p map dump id 567

Without Patch:
[{
         "key": ["0xc0","0x00","0x02","0x05","0x27","0x16","0x06","0x00"
         ],
         "value": ["0x38","0x02","0x00","0x00"
         ]
     }
]

With Patch:
[{
         "key": ["0xc0","0x00","0x02","0x05","0x27","0x16","0x06","0x00"
         ],
         "value": ["0x38","0x02","0x00","0x00"
         ],
         "inner_map_id": 568
     }
]
```

Signed-off-by: Xueming Feng <kuro@xxxxxxxx>

You can carry my Ack from v3 since there is no big changes.
Anyway, Ack again.

Acked-by: Yonghong Song <yhs@xxxxxx>

---

Changes in v4:
  - Remove unnecessary parenthesis ('{}').

Changes in v3:
  - In plain print, use printf() directly since inner map id is always a 32bit int.
  - Remove unused print_uint() function.
  - Rename `id` to `inner_map_id` in plain print output for clearness.
  - Add a new `inner_map_id` field to json output.
  - Add example output to commit message.

Changes in v2:
  - Fix commit message grammar.
  - Change `print_uint` to only print to stdout, make `arg` const,
    and rename `n` to `arg_size`.
  - Make `print_uint` able to take any size of argument up to `unsigned long`,
    and print it as unsigned decimal.

  tools/bpf/bpftool/map.c | 12 ++++++++++--
  1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index aaeb8939e137..ae9e822aa3fe 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -139,6 +139,9 @@ static void print_entry_json(struct bpf_map_info *info, unsigned char *key,
  		print_hex_data_json(key, info->key_size);
  		jsonw_name(json_wtr, "value");
  		print_hex_data_json(value, info->value_size);
+		if (map_is_map_of_maps(info->type))
+			jsonw_uint_field(json_wtr, "inner_map_id",
+					 *(unsigned int *)value);
  		if (btf) {
  			struct btf_dumper d = {
  				.btf = btf,
@@ -259,8 +262,13 @@ static void print_entry_plain(struct bpf_map_info *info, unsigned char *key,
  		}
if (info->value_size) {
-			printf("value:%c", break_names ? '\n' : ' ');
-			fprint_hex(stdout, value, info->value_size, " ");
+			if (map_is_map_of_maps(info->type)) {
+				printf("inner_map_id:%c", break_names ? '\n' : ' ');
+				printf("%u ", *(unsigned int *)value);
+			} else {
+				printf("value:%c", break_names ? '\n' : ' ');
+				fprint_hex(stdout, value, info->value_size, " ");
+			}
  		}
printf("\n");



[Index of Archives]     [Linux Samsung SoC]     [Linux Rockchip SoC]     [Linux Actions SoC]     [Linux for Synopsys ARC Processors]     [Linux NFS]     [Linux NILFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]


  Powered by Linux