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@vger.kernel.org # v4.9.258 Signed-off-by: Xiaoming Ni nixiaoming@huawei.com
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@linaro.org
Thanks, now queued up.
greg k-h