linux-kernel - Re: [PATCH 4.4 3/3] futex: fix dead code in attach_to_pi

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Message-ID: <YEdQoy6j7eOne+8h@kroah.com>
Date:   Tue, 9 Mar 2021 11:40:35 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Zheng Yejian <zhengyejian1@...wei.com>
Cc:     lee.jones@...aro.org, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org, tglx@...utronix.de,
        cj.chengjian@...wei.com, judy.chenhui@...wei.com,
        zhangjinhao2@...wei.com, nixiaoming@...wei.com
Subject: Re: [PATCH 4.4 3/3] futex: fix dead code in attach_to_pi_owner()

On Tue, Mar 09, 2021 at 11:06:05AM +0800, Zheng Yejian wrote:
> From: Thomas Gleixner <tglx@...utronix.de>
> 
> The handle_exit_race() function is defined in commit 9c3f39860367
>  ("futex: Cure exit race"), which never returns -EBUSY. This results
> in a small piece of dead code in the attach_to_pi_owner() function:
> 
> 	int ret = handle_exit_race(uaddr, uval, p); /* Never return -EBUSY */
> 	...
> 	if (ret == -EBUSY)
> 		*exiting = p; /* dead code */
> 
> The return value -EBUSY is added to handle_exit_race() in upsteam
> commit ac31c7ff8624409 ("futex: Provide distinct return value when
> owner is exiting"). This commit was incorporated into v4.9.255, before
> the function handle_exit_race() was introduced, whitout Modify
> handle_exit_race().
> 
> To fix dead code, extract the change of handle_exit_race() from
> commit ac31c7ff8624409 ("futex: Provide distinct return value when owner
>  is exiting"), re-incorporated.
> 
> Lee writes:
> 
> This commit takes the remaining functional snippet of:
> 
>  ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting")
> 
> ... and is the correct fix for this issue.
> 
> Fixes: 9c3f39860367 ("futex: Cure exit race")
> Cc: stable@...r.kernel.org # v4.9.258
> Signed-off-by: Xiaoming Ni <nixiaoming@...wei.com>
> Reviewed-by: Lee Jones <lee.jones@...aro.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Zheng Yejian <zhengyejian1@...wei.com>
> ---
>  kernel/futex.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Same here, what is the upstream git id?

thanks,

greg k-h