On Thu, Feb 25, 2021 at 09:17:38AM +0000, Lee Jones wrote:
> On Wed, 24 Feb 2021, Xiaoming Ni wrote:
>
> > 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.
> >
> > Fixes: 9c3f39860367 ("futex: Cure exit race")
> > Cc: stable@xxxxxxxxxxxxxxx # v4.9.258
> > Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
> > ---
> > kernel/futex.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
>
> To clarify, this is not a wholesale back-port from Mainline.
>
> It takes the remaining functional snippet of:
>
> ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting")
>
> ... and is the correct fix for this issue.
>
> Reviewed-by: Lee Jones <lee.jones@xxxxxxxxxx>
Thanks, now queued up.
greg k-h
