Re: [PATCH stable-rc queue/4.9 1/1] futex: Provide distinct return value when owner is exiting

[Xiaoming Ni]

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@xxxxxxxxxxxxx>
> > > > > >
> > > > > > 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@xxxxxxxxxx/
> > > >
> > > >
> > > > 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@xxxxxxxxxx/
> > >
> > > 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@xxxxxxxxxx/
>
> 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