Messages in this thread | | | Subject | Re: [PATCH 4.4 3/3] futex: fix dead code in attach_to_pi_owner() | From | "Zhengyejian (Zetta)" <> | Date | Thu, 11 Mar 2021 09:39:19 +0800 |
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On 2021/3/10 22:10, Greg KH wrote: > On Wed, Mar 10, 2021 at 01:28:02PM +0000, Lee Jones wrote: >> On Wed, 10 Mar 2021, Greg KH wrote: >> >>> 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 :( >> >> This was also my thinking, which is why I replied to the original >> patch in an attempt to clarify what I thought was happening. >> >>> Is this a backport of another patch in the stable tree somewhere? >> >> Yes, it looks like it. >> >> The full patch was back-ported to v4.14 as: >> >> e6e00df182908f34360c3c9f2d13cc719362e9c0 > > Ok, Zheng, can you put this information in the patch and resend the > whole series? >
Sure, I'll send a "v2" patchset soon. Thanks for your suggestions,
Zheng Yejian
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