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Subject: Re: [PATCH v8 6/9] livepatch: Use kallsyms_on_each_match_symbol() to
 improve performance
To:     Luis Chamberlain <mcgrof@kernel.org>
CC:     Petr Mladek <pmladek@suse.com>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Jiri Kosina <jikos@kernel.org>,
        Miroslav Benes <mbenes@suse.cz>,
        Joe Lawrence <joe.lawrence@redhat.com>,
        <live-patching@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Jiri Olsa <jolsa@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        <linux-modules@vger.kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        David Laight <David.Laight@aculab.com>
References: <20221102084921.1615-1-thunder.leizhen@huawei.com>
 <20221102084921.1615-7-thunder.leizhen@huawei.com> <Y34f+IqqSGbtC82V@alley>
 <45a28bcf-c6e1-8d39-613a-d30bd7b685f0@huawei.com>
 <Y4+9Zr1BBqsYRxqT@bombadil.infradead.org>
From:   "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
Message-ID: <c5e3a54d-cd05-1081-2e76-01ca61ce3a8a@huawei.com>
Date:   Wed, 7 Dec 2022 09:30:31 +0800
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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