linux-kernel - Re: [PATCH v8 7/9] livepatch: Improve the search performance of module_kallsyms_on_each

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Message-ID: <b53c5873-4f83-915b-c5ac-9594f7964dcb@huawei.com>
Date:   Thu, 24 Nov 2022 10:41:46 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Petr Mladek <pmladek@...e.com>
CC:     Josh Poimboeuf <jpoimboe@...nel.org>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        <live-patching@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Masahiro Yamada" <masahiroy@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        <linux-modules@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        "Ingo Molnar" <mingo@...hat.com>,
        David Laight <David.Laight@...lab.com>
Subject: Re: [PATCH v8 7/9] livepatch: Improve the search performance of
 module_kallsyms_on_each_symbol()



On 2022/11/23 21:57, Petr Mladek wrote:
> On Wed 2022-11-02 16:49:19, Zhen Lei wrote:
>> Currently we traverse all symbols of all modules to find the specified
>> function for the specified module. But in reality, we just need to find
>> the given module and then traverse all the symbols in it.
>>
>> Let's add a new parameter 'const char *modname' to function
>> module_kallsyms_on_each_symbol(), then we can compare the module names
>> directly in this function and call hook 'fn' after matching. And the
>> parameter 'struct module *' in the hook 'fn' can also be deleted.
>>
>> Phase1: mod1-->mod2..(subsequent modules do not need to be compared)
>>                 |
>> Phase2:          -->f1-->f2-->f3
> 
> Just for record. The patch looks good from the livepatching code POV.
> 
> But I guess that it will need to get updated to support the new
> callers in the ftrace and bpf code.

Yes, this patch and 8/9 conflicts with the patch series of Jiri Olsa,
So they didn't merge into linux-next. I will update and repost after
v6.2-rc1.

> 
> Best Regards,
> Petr
> .
> 

-- 
Regards,
  Zhen Lei