Re: [PATCH v8 6/9] livepatch: Use kallsyms_on_each_match_symbol() to improve performance

Leizhen (ThunderTown)
2022-12-07T01:42:07Z

On 2022/12/7 6:08, Luis Chamberlain wrote:
> On Thu, Nov 24, 2022 at 10:36:23AM +0800, Leizhen (ThunderTown) wrote:
>>
>>
>> On 2022/11/23 21:28, Petr Mladek wrote:
>>> Hi,
>>>
>>> I am sorry for the late review. I have been snowed under another
>>> tasks.
>>>
>>> On Wed 2022-11-02 16:49:18, Zhen Lei wrote:
>>>> Based on the test results of kallsyms_on_each_match_symbol() and
>>>> kallsyms_on_each_symbol(), the average performance can be improved by
>>>> more than 1500 times.
>>>
>>> Sounds great.
>>>
>>>> --- a/kernel/livepatch/core.c
>>>> +++ b/kernel/livepatch/core.c
>>>> @@ -153,6 +153,24 @@ static int klp_find_callback(void *data, const char *name,
>>>> return 0;
>>>> }
>>>>
>>>> +static int klp_match_callback(void *data, unsigned long addr)
>>>> +{
>>>> + struct klp_find_arg *args = data;
>>>> +
>>>> + args->addr = addr;
>>>> + args->count++;
>>>> +
>>>> + /*
>>>> + * Finish the search when the symbol is found for the desired position
>>>> + * or the position is not defined for a non-unique symbol.
>>>> + */
>>>> + if ((args->pos && (args->count == args->pos)) ||
>>>> + (!args->pos && (args->count > 1)))
>>>> + return 1;
>>>> +
>>>> + return 0;
>>>
>>> This duplicates most of the klp_find_callback(). Please, call this
>>> new function in klp_find_callback() instead of the duplicated code.
>>> I mean to do:
>>>
>>> static int klp_find_callback(void *data, const char *name, unsigned long addr)
>>> {
>>> struct klp_find_arg *args = data;
>>>
>>> if (strcmp(args->name, name))
>>> return 0;
>>>
>>> return klp_match_callback(data, addr);
>>> }
>>
>> Good idea. But these patches have been merged into linux-next, how about I post
>> a new cleanup patch after v6.2-rc1?
>
> You can send the cleanup now. The code doesn't change drastically, just
> base it on modules-next.

OK

>
> Luis
> .
>

--
Regards,
Zhen Lei