Re: [PATCH] acpi: scan: Fix a possible data race in acpi_scan_hotplug_enabled

From: Rafael J. Wysocki
Date: Wed May 09 2018 - 03:54:33 EST


On Wed, May 9, 2018 at 5:17 AM, Jia-Ju Bai <baijiaju1990@xxxxxxxxx> wrote:
>
>
> On 2018/5/9 4:17, Rafael J. Wysocki wrote:
>>
>> On Tue, May 8, 2018 at 5:08 AM, Jia-Ju Bai <baijiaju1990@xxxxxxxxx> wrote:
>>>
>>> The write operation to "hotplug->enabled" is protected by
>>> the lock on line 1760, but the read operation to
>>> this data on line 1755 is not protected by the lock.
>>> Thus, there may exist a data race for "hotplug->enabled".
>>
>> Either it does exist, or it doesn't.
>>
>> If it exists, it needs to be fixed. If it doesn't exist, nothing
>> needs to be done.
>>
>> Which is the case?
>
>
> I only read the code and find this possible data race.
> It is not found in real driver execution.
> I am not sure of it, so I use "may" and "possible" here.

It looks like you are not actually sure what you are doing then.