linux-kernel - Re: [PATCH 2/2] module: deal with the failure of complete

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Date:	Wed, 06 Jan 2016 09:14:42 +0800
From:	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
To:	Steven Rostedt <rostedt@...dmis.org>,
	"Qiu, PeiyangX" <peiyangx.qiu@...el.com>
CC:	Ingo Molnar <mingo@...hat.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] module: deal with the failure of complete_formation

On 2016/1/6 9:01, Steven Rostedt wrote:
> On Fri, 25 Dec 2015 15:03:13 +0800
> "Qiu, PeiyangX" <peiyangx.qiu@...el.com> wrote:
>
>> From: Qiu Peiyang <peiyangx.qiu@...el.com>
>>
>> complete_formation might fail. kernel need clean up
>> ftrace records of the module.
>>
>> The patch fixes it by tuning the operation sequence in
>> complete_formation. After complete_formation checks
>> verify_export_symbols, call ftrace_module_init to init
>> ftrace records.
>>
>> Signed-off-by: Qiu Peiyang <peiyangx.qiu@...el.com>
>> Signed-off-by: Zhang Yanmin <yanmin.zhang@...el.com>
>> ---
>>  kernel/module.c | 9 +++++----
>>  1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/kernel/module.c b/kernel/module.c
>> index 8f051a1..0a67c4e 100644
>> --- a/kernel/module.c
>> +++ b/kernel/module.c
>> @@ -3373,6 +3373,11 @@ static int complete_formation(struct module *mod, struct load_info *info)
>>  	/* This relies on module_mutex for list integrity. */
>>  	module_bug_finalize(info->hdr, info->sechdrs, mod);
>>  
>> +	mutex_unlock(&module_mutex);
>> +
> First of all, this is buggy. You can't just move the locking of
> module_mutex. That is needed to modify mod->state.
>
> Second of all, you are solving this wrong. I guess we should add
> ftrace_module_init_fail() function to cover the cases where the module
> can fail before calling do_init_module(), as if that happens it does
> not call the module going notifiers.

It's a good idea although ftrace_module_init_fail might be complicated.

Thanks,
Yanmin

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