linux-kernel - Re: [PATCH v3 5/8] module: Add module_for_each

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Message-ID: <17c0cce7-03c7-488a-b61a-6c41d5bacfa1@suse.com>
Date: Wed, 5 Mar 2025 09:47:49 +0100
From: Petr Pavlu <petr.pavlu@...e.com>
To: Steven Rostedt <rostedt@...dmis.org>, Luis Chamberlain <mcgrof@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
 Masami Hiramatsu <mhiramat@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Sami Tolvanen <samitolvanen@...gle.com>, Daniel Gomez
 <da.gomez@...sung.com>, linux-modules@...r.kernel.org
Subject: Re: [PATCH v3 5/8] module: Add module_for_each_mod() function

On 3/4/25 15:57, Steven Rostedt wrote:
> 
> Luis,
> 
> Can I get an Acked-by from you?
> 
> This follows the changes you have in linux-next.

Hi Steven,

I'm not Luis, but we started rotating the modules maintenance every six
months and I'm currently looking after the modules tree. I see Luis
seemed ok with the change in the previous discussion and the patch looks
reasonable to me.

Acked-by: Petr Pavlu <petr.pavlu@...e.com>

-- 
Thanks,
Petr

> 
> 
> 
> 
> On Mon, 03 Mar 2025 20:25:21 -0500
> Steven Rostedt <rostedt@...dmis.org> wrote:
> 
>> From: Steven Rostedt <rostedt@...dmis.org>
>>
>> The tracing system needs a way to save all the currently loaded modules
>> and their addresses into persistent memory so that it can evaluate the
>> addresses on a reboot from a crash. When the persistent memory trace
>> starts, it will load the module addresses and names into the persistent
>> memory. To do so, it will call the module_for_each_mod() function and pass
>> it a function and data structure to get called on each loaded module. Then
>> it can record the memory.
>>
>> This only implements that function.
>>
>> Cc: Luis Chamberlain <mcgrof@...nel.org>
>> Cc: Petr Pavlu <petr.pavlu@...e.com>
>> Cc: Sami Tolvanen <samitolvanen@...gle.com>
>> Cc: Daniel Gomez <da.gomez@...sung.com>
>> Cc: linux-modules@...r.kernel.org
>> Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
>> ---
>> Changes since v2: https://lore.kernel.org/20250215034404.902259250@goodmis.org
>>
>> - Use RCU guard instead of disabling preemption
>>
>>  include/linux/module.h |  6 ++++++
>>  kernel/module/main.c   | 13 +++++++++++++
>>  2 files changed, 19 insertions(+)
>>
>> diff --git a/include/linux/module.h b/include/linux/module.h
>> index 30e5b19bafa9..9a71dd2cb11f 100644
>> --- a/include/linux/module.h
>> +++ b/include/linux/module.h
>> @@ -782,6 +782,8 @@ static inline void *module_writable_address(struct module *mod, void *loc)
>>  	return __module_writable_address(mod, loc);
>>  }
>>  
>> +void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data);
>> +
>>  #else /* !CONFIG_MODULES... */
>>  
>>  static inline struct module *__module_address(unsigned long addr)
>> @@ -894,6 +896,10 @@ static inline void *module_writable_address(struct module *mod, void *loc)
>>  {
>>  	return loc;
>>  }
>> +
>> +static inline void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data)
>> +{
>> +}
>>  #endif /* CONFIG_MODULES */
>>  
>>  #ifdef CONFIG_SYSFS
>> diff --git a/kernel/module/main.c b/kernel/module/main.c
>> index 1fb9ad289a6f..927a2e0ffd5f 100644
>> --- a/kernel/module/main.c
>> +++ b/kernel/module/main.c
>> @@ -3809,6 +3809,19 @@ bool is_module_text_address(unsigned long addr)
>>  	return ret;
>>  }
>>  
>> +void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data)
>> +{
>> +	struct module *mod;
>> +
>> +	guard(rcu)();
>> +	list_for_each_entry_rcu(mod, &modules, list) {
>> +		if (mod->state == MODULE_STATE_UNFORMED)
>> +			continue;
>> +		if (func(mod, data))
>> +			break;
>> +	}
>> +}
>> +
>>  /**
>>   * __module_text_address() - get the module whose code contains an address.
>>   * @addr: the address.
>