Messages in this thread | | | Subject | Re: [PATCH stable-rc queue/4.9 1/1] futex: Provide distinct return value when owner is exiting | From | Xiaoming Ni <> | Date | Mon, 22 Feb 2021 18:54:06 +0800 |
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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/
Thanks Xiaoming Ni
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