On Thu, Mar 11, 2021 at 11:25:57AM +0800, Zheng Yejian wrote: > Changelog for 'v2': > Complete commit messages with needed git commit ids as Greg and Lee > suggested. > > Lee sent a patchset to update Futex for v4.9, see > https://www.spinics.net/lists/stable/msg443081.html, > Then Xiaoming sent a follow-up patch for it, see > https://lore.kernel.org/lkml/20210225093120.GD641347@dell/. > > These 3 patches is directly picked from v4.9, > and they may also resolve following issues in 4.4.260 which have been > reported in v4.9, > see > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/?h=linux-4.4.y&id=319f66f08de1083c1fe271261665c209009dd65a > > /* > > * The task is on the way out. When the futex state is > > * FUTEX_STATE_DEAD, we know that the task has finished > > * the cleanup: > > */ > > int ret = (p->futex_state = FUTEX_STATE_DEAD) ? -ESRCH : -EAGAIN; > > Here may be: > int ret = (p->futex_state == FUTEX_STATE_DEAD) ? -ESRCH : -EAGAIN; > > > raw_spin_unlock_irq(&p->pi_lock); > > /* > > * If the owner task is between FUTEX_STATE_EXITING and > > * FUTEX_STATE_DEAD then store the task pointer and keep > > * the reference on the task struct. The calling code will > > * drop all locks, wait for the task to reach > > * FUTEX_STATE_DEAD and then drop the refcount. This is > > * required to prevent a live lock when the current task > > * preempted the exiting task between the two states. > > */ > > if (ret == -EBUSY) > > And here, the variable "ret" may only be "-ESRCH" or "-EAGAIN", but not > "-EBUSY". > > > *exiting = p; > > else > > put_task_struct(p); > > Since 074e7d515783 ("futex: Ensure the correct return value from > futex_lock_pi()") has > been merged in 4.4.260, I send the remain 3 patches. > > Peter Zijlstra (1): > futex: Change locking rules > > Thomas Gleixner (2): > futex: Cure exit race > futex: fix dead code in attach_to_pi_owner() > > kernel/futex.c | 209 +++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 177 insertions(+), 32 deletions(-)
All now queued up, thanks. greg k-h
