linux-kernel - Re: [PATCH v2 1/5] thermal/drivers/core: Use a char pointer for the cooling device name

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Message-ID: <f51fcec0-1483-cecb-d984-591097c324ca@linaro.org>
Date:   Fri, 12 Mar 2021 22:01:01 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Lukasz Luba <lukasz.luba@....com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Jiri Pirko <jiri@...dia.com>, Ido Schimmel <idosch@...dia.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Amit Kucheria <amitk@...nel.org>,
        "open list:MELLANOX ETHERNET SWITCH DRIVERS" <netdev@...r.kernel.org>
Subject: Re: [PATCH v2 1/5] thermal/drivers/core: Use a char pointer for the
 cooling device name

On 12/03/2021 19:49, Lukasz Luba wrote:
> 
> 
> On 3/12/21 5:03 PM, Daniel Lezcano wrote:
>> We want to have any kind of name for the cooling devices as we do no
>> longer want to rely on auto-numbering. Let's replace the cooling
>> device's fixed array by a char pointer to be allocated dynamically
>> when registering the cooling device, so we don't limit the length of
>> the name.
>>
>> Rework the error path at the same time as we have to rollback the
>> allocations in case of error.
>>
>> Tested with a dummy device having the name:
>>   "Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch"
>>
>> A village on the island of Anglesey (Wales), known to have the longest
>> name in Europe.
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
>> ---
>>   .../ethernet/mellanox/mlxsw/core_thermal.c    |  2 +-
>>   drivers/thermal/thermal_core.c                | 38 +++++++++++--------
>>   include/linux/thermal.h                       |  2 +-
>>   3 files changed, 24 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
>> b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
>> index bf85ce9835d7..7447c2a73cbd 100644
>> --- a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
>> +++ b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
>> @@ -141,7 +141,7 @@ static int mlxsw_get_cooling_device_idx(struct
>> mlxsw_thermal *thermal,
>>       /* Allow mlxsw thermal zone binding to an external cooling
>> device */
>>       for (i = 0; i < ARRAY_SIZE(mlxsw_thermal_external_allowed_cdev);
>> i++) {
>>           if (strnstr(cdev->type, mlxsw_thermal_external_allowed_cdev[i],
>> -                sizeof(cdev->type)))
>> +                strlen(cdev->type)))
>>               return 0;
>>       }
>>   diff --git a/drivers/thermal/thermal_core.c
>> b/drivers/thermal/thermal_core.c
>> index 996c038f83a4..9ef8090eb645 100644
>> --- a/drivers/thermal/thermal_core.c
>> +++ b/drivers/thermal/thermal_core.c
>> @@ -960,10 +960,7 @@ __thermal_cooling_device_register(struct
>> device_node *np,
>>   {
>>       struct thermal_cooling_device *cdev;
>>       struct thermal_zone_device *pos = NULL;
>> -    int result;
>> -
>> -    if (type && strlen(type) >= THERMAL_NAME_LENGTH)
>> -        return ERR_PTR(-EINVAL);
>> +    int ret;
>>         if (!ops || !ops->get_max_state || !ops->get_cur_state ||
>>           !ops->set_cur_state)
>> @@ -973,14 +970,17 @@ __thermal_cooling_device_register(struct
>> device_node *np,
>>       if (!cdev)
>>           return ERR_PTR(-ENOMEM);
>>   -    result = ida_simple_get(&thermal_cdev_ida, 0, 0, GFP_KERNEL);
>> -    if (result < 0) {
>> -        kfree(cdev);
>> -        return ERR_PTR(result);
>> +    ret = ida_simple_get(&thermal_cdev_ida, 0, 0, GFP_KERNEL);
>> +    if (ret < 0)
>> +        goto out_kfree_cdev;
>> +    cdev->id = ret;
>> +
>> +    cdev->type = kstrdup(type ? type : "", GFP_KERNEL);
>> +    if (!cdev->type) {
>> +        ret = -ENOMEM;
> 
> Since we haven't called the device_register() yet, I would call here:
> kfree(cdev);
> and then jump

I'm not sure to understand, we have to remove the ida, no ?

> Other than that, LGTM
> 
> Reviewed-by: Lukasz Luba <lukasz.luba@....com>
> 
> Regards,
> Lukasz


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