netdev - Re: [PATCH] net: thunderbolt: Fix error handling in tbnet

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Date:   Mon, 14 Nov 2022 20:06:17 +0800
From:   Yuan Can <yuancan@...wei.com>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
CC:     <michael.jamet@...el.com>, <YehezkelShB@...il.com>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <andriy.shevchenko@...ux.intel.com>,
        <amir.jer.levy@...el.com>, <netdev@...r.kernel.org>
Subject: Re: [PATCH] net: thunderbolt: Fix error handling in tbnet_init()

在 2022/11/14 18:09, Mika Westerberg 写道:
> Hi,
>
> On Mon, Nov 14, 2022 at 08:19:36AM +0000, Yuan Can wrote:
>> A problem about insmod thunderbolt-net failed is triggered with following
>> log given while lsmod does not show thunderbolt_net:
>>
>>   insmod: ERROR: could not insert module thunderbolt-net.ko: File exists
>>
>> The reason is that tbnet_init() returns tb_register_service_driver()
>> directly without checking its return value, if tb_register_service_driver()
>> failed, it returns without removing property directory, resulting the
>> property directory can never be created later.
>>
>>   tbnet_init()
>>     tb_register_property_dir() # register property directory
>>     tb_register_service_driver()
>>       driver_register()
>>         bus_add_driver()
>>           priv = kzalloc(...) # OOM happened
>>     # return without remove property directory
>>
>> Fix by remove property directory when tb_register_service_driver() returns
>> error.
>>
>> Fixes: e69b6c02b4c3 ("net: Add support for networking over Thunderbolt cable")
>> Signed-off-by: Yuan Can <yuancan@...wei.com>
>> ---
>>   drivers/net/thunderbolt.c | 9 ++++++++-
>>   1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/thunderbolt.c b/drivers/net/thunderbolt.c
>> index 83fcaeb2ac5e..fe6a9881cc75 100644
>> --- a/drivers/net/thunderbolt.c
>> +++ b/drivers/net/thunderbolt.c
>> @@ -1396,7 +1396,14 @@ static int __init tbnet_init(void)
>>   		return ret;
>>   	}
>>   
>> -	return tb_register_service_driver(&tbnet_driver);
>> +	ret = tb_register_service_driver(&tbnet_driver);
>> +	if (ret) {
>> +		tb_unregister_property_dir("network", tbnet_dir);
>> +		tb_property_free_dir(tbnet_dir);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
> Okay but I suggest that you make it like:
>
> 	ret = tb_register_property_dir("network", tbnet_dir);
> 	if (ret)
> 		goto err_free_dir;
>
> 	ret = tb_register_service_driver(&tbnet_driver);
> 	if (ret)
> 		goto err_unregister;
>
> 	return 0;
>
> err_unregister:
> 	tb_unregister_property_dir("network", tbnet_dir);
> err_free_dir:
> 	tb_property_free_dir(tbnet_dir);
>
> 	return ret;
>
> }
Ok, thanks for the suggestion! I will switch to this style in the v2 patch.

-- 
Best regards,
Yuan Can