From: Greg KH <gregkh@linuxfoundation.org>
To: Lee Jones <lee.jones@linaro.org>
Cc: Zheng Yejian <zhengyejian1@huawei.com>,
stable@vger.kernel.org, linux-kernel@vger.kernel.org,
tglx@linutronix.de, cj.chengjian@huawei.com,
judy.chenhui@huawei.com, zhangjinhao2@huawei.com,
nixiaoming@huawei.com
Subject: Re: [PATCH 4.4 3/3] futex: fix dead code in attach_to_pi_owner()
Date: Wed, 10 Mar 2021 13:00:48 +0100 [thread overview]
Message-ID: <YEi08Dr3cgNp0KlP@kroah.com> (raw)
In-Reply-To: <20210309181437.GV4931@dell>
On Tue, Mar 09, 2021 at 06:14:37PM +0000, Lee Jones wrote:
> On Tue, 09 Mar 2021, Greg KH wrote:
>
> > On Tue, Mar 09, 2021 at 11:06:05AM +0800, Zheng Yejian wrote:
> > > From: Thomas Gleixner <tglx@linutronix.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@vger.kernel.org # v4.9.258
> > > Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
> > > Reviewed-by: Lee Jones <lee.jones@linaro.org>
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
> > > ---
> > > kernel/futex.c | 6 +++---
> > > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > Same here, what is the upstream git id?
>
> It doesn't have one as such - it's a part-patch:
>
> > > This commit takes the remaining functional snippet of:
> > >
> > > ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting")
That wasn't obvious :(
Is this a backport of another patch in the stable tree somewhere?
confused,
greg k-h
next prev parent reply other threads:[~2021-03-10 12:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-09 3:06 [PATCH 4.4 0/3] Backport patch series to update Futex from 4.9 Zheng Yejian
2021-03-09 3:06 ` [PATCH 4.4 1/3] futex: Change locking rules Zheng Yejian
2021-03-09 10:40 ` Greg KH
2021-03-09 3:06 ` [PATCH 4.4 2/3] futex: Cure exit race Zheng Yejian
2021-03-09 3:06 ` [PATCH 4.4 3/3] futex: fix dead code in attach_to_pi_owner() Zheng Yejian
2021-03-09 10:40 ` Greg KH
2021-03-09 18:14 ` Lee Jones
2021-03-10 12:00 ` Greg KH [this message]
2021-03-10 13:28 ` Lee Jones
2021-03-10 14:10 ` Greg KH
2021-03-11 1:39 ` Zhengyejian (Zetta)
2021-03-09 10:41 ` [PATCH 4.4 0/3] Backport patch series to update Futex from 4.9 Greg KH
2021-03-11 3:48 ` Zhengyejian (Zetta)
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