Re: [PATCH v4 2/8] scripts/kallsyms: ensure that all possible combinations are compressed

Leizhen (ThunderTown)
2022-09-21T12:47:00Z

On 2022/9/21 16:31, Leizhen (ThunderTown) wrote:
>
>
> On 2022/9/21 16:00, Petr Mladek wrote:
>> On Tue 2022-09-20 15:13:11, Zhen Lei wrote:
>>> For a symbol, there may be more than one place that can be merged. For
>>> example: nfs_fs_proc_net_init, there are two "f"+"s_" combinations.
>>> And we're only compressing the first combination at the moment.
>>
>> Really?
>
> Yes, there are about 200 such functions.
>
>>
>>> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
>>> index 8caccc8f4a23703..3319d9f38d7a5f2 100644
>>> --- a/scripts/kallsyms.c
>>> +++ b/scripts/kallsyms.c
>>> @@ -553,7 +553,7 @@ static void compress_symbols(const unsigned char *str, int idx)
>>> unsigned char *p1, *p2;
>>>
>>> for (i = 0; i < table_cnt; i++) {
>>> -
>>> +retry:
>>> len = table[i]->len;
>>> p1 = table[i]->sym;
>>>
>>> @@ -585,6 +585,9 @@ static void compress_symbols(const unsigned char *str, int idx)
>>>
>>> /* increase the counts for this symbol's new tokens */
>>> learn_symbol(table[i]->sym, len);
>>> +
>>> + /* May be more than one place that can be merged, try again */
>>> + goto retry;
>>> }
>>> }
>>
>> My understanding is that the code already tries to find the same
>> token several times. Here are the important parts of the existing
>> code:
>>
>> static void compress_symbols(const unsigned char *str, int idx)
>> {
>>
>> p2 = find_token(p1, len, str);
>>
>> do {
>> /* replace the found token with idx */
>> *p2 = idx;
>> [...]
>>
>> /* find the token on the symbol */
>> p2 = find_token(p1, size, str);
>
> Oh, yes, it retries. Let me reanalyze it. However, the problem is
> real, and there may be a problem somewhere in the loop.

Hi, Petr:
Thanks. I found that it's my fault. The first round skip the type
character. But the next round will incorrectly skip one character,
so for nfs_fs_proc_net_init, the next round start from s, and using
^
the proposed "unsigned char type" in your next reply should solve
the problem. Thank you very much.

- for (i = 0; i < len - 1; i++)
+ for (i = sym_start_idx; i < len - 1; i++)

>
>>
>> } while (p2);
>>
>> Best Regards,
>> Petr
>> .
>>
>

--
Regards,
Zhen Lei