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SubjectRe: [PATCH stable-rc queue/4.9 1/1] futex: Provide distinct return value when owner is exiting
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On 2021/2/23 21:00, Greg KH wrote:
> On Mon, Feb 22, 2021 at 10:11:37PM +0800, Xiaoming Ni wrote:
>> On 2021/2/22 20:09, Greg KH wrote:
>>> On Mon, Feb 22, 2021 at 06:54:06PM +0800, Xiaoming Ni wrote:
>>>> On 2021/2/22 18:16, Greg KH wrote:
>>>>> On Mon, Feb 22, 2021 at 03:03:28PM +0800, Xiaoming Ni wrote:
>>>>>> From: Thomas Gleixner<tglx@linutronix.de>
>>>>>>
>>>>>> commit ac31c7ff8624409ba3c4901df9237a616c187a5d upstream.
>>>>> This commit is already in the 4.9 tree. If the backport was incorrect,
>>>>> say that here, and describe what went wrong and why this commit fixes
>>>>> it.
>>>>>
>>>>> Also state what commit this fixes as well, otherwise this changelog just
>>>>> looks like it is being applied again to the tree, which doesn't make
>>>>> much sense.
>>>>>
>>>>> thanks,
>>>>>
>>>>> greg k-h
>>>>> .
>>>>
>>>> I wrote a cover for it. but forgot to adjust the title of the cover:
>>>>
>>>> https://lore.kernel.org/lkml/20210222070328.102384-1-nixiaoming@huawei.com/
>>>>
>>>>
>>>> I found a dead code in the queue/4.9 branch of the stable-rc repository.
>>>>
>>>> 2021-02-03:
>>>> commit c27f392040e2f6 ("futex: Provide distinct return value when
>>>> owner is exiting")
>>>> The function handle_exit_race does not exist. Therefore, the
>>>> change in handle_exit_race() is ignored in the patch round.
>>>>
>>>> 2021-02-22:
>>>> commit e55cb811e612 ("futex: Cure exit race")
>>>> Define the handle_exit_race() function,
>>>> but no branch in the function returns EBUSY.
>>>> As a result, dead code occurs in the attach_to_pi_owner():
>>>>
>>>> int ret = handle_exit_race(uaddr, uval, p);
>>>> ...
>>>> if (ret == -EBUSY)
>>>> *exiting = p; /* dead code */
>>>>
>>>> To fix the dead code, modify the commit e55cb811e612 ("futex: Cure exit
>>>> race"),
>>>> or install a patch to incorporate the changes in handle_exit_race().
>>>>
>>>> I am unfamiliar with the processing of the stable-rc queue branch,
>>>> and I cannot find the patch mail of the current branch in
>>>> https://lore.kernel.org/lkml/?q=%22futex%3A+Cure+exit+race%22
>>>> Therefore, I re-integrated commit ac31c7ff8624 ("futex: Provide distinct
>>>> return value when owner is exiting").
>>>> And wrote a cover (but forgot to adjust the title of the cover):
>>>>
>>>> https://lore.kernel.org/lkml/20210222070328.102384-1-nixiaoming@huawei.com/
>>>
>>> So this is a "fixup" patch, right?
>>>
>>> Please clearly label it as such in your patch description and resend
>>> this as what is here I can not apply at all.
>>>
>>> thanks,
>>>
>>> greg k-h
>>> .
>>>
>> Thank you for your guidance.
>> I have updated the patch description and resent the patch based on
>> v4.9.258-rc1
>> https://lore.kernel.org/lkml/20210222125352.110124-1-nixiaoming@huawei.com/
>
> Can you please try 4.9.258 and let me know if this is still needed or
> not?
>
> thanks,
>
> greg k-h
> .
>
The dead code problem still exists in V4.9.258. No conflict occurs
during my patch integration. Do I need to correct the version number
marked in the cc table in the patch and resend the patch?

Thanks
Xiaoming Ni

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