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

[Leizhen (ThunderTown)]

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?

> 
> Otherwise, it looks good.
> 
> Best Regards,
> Petr
> .
> 

-- 
Regards,
  Zhen Lei