On 04/12/2018 10:06 AM, Will Deacon wrote: > On Wed, Apr 11, 2018 at 03:53:16PM -0400, Waiman Long wrote: >>> diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c >>> index 396701e8c62d..a8fc402b3f3a 100644 >>> --- a/kernel/locking/qspinlock.c >>> +++ b/kernel/locking/qspinlock.c >>> @@ -162,6 +162,17 @@ struct __qspinlock { >>> >>> #if _Q_PENDING_BITS == 8 >>> /** >>> + * clear_pending - clear the pending bit. >>> + * @lock: Pointer to queued spinlock structure >>> + * >>> + * *,1,* -> *,0,* >>> + */ >>> +static __always_inline void clear_pending(struct qspinlock *lock) >>> +{ >>> + WRITE_ONCE(lock->pending, 0); >>> +} >>> + >>> +/** >>> * clear_pending_set_locked - take ownership and clear the pending bit. >>> * @lock: Pointer to queued spinlock structure >>> * >>> @@ -201,6 +212,17 @@ static __always_inline u32 xchg_tail(struct qspinlock >>> *lock, u32 tail) >>> #else /* _Q_PENDING_BITS == 8 */ >>> >>> /** >>> + * clear_pending - clear the pending bit. >>> + * @lock: Pointer to queued spinlock structure >>> + * >>> + * *,1,* -> *,0,* >>> + */ >>> +static __always_inline void clear_pending(struct qspinlock *lock) >>> +{ >>> + atomic_andnot(_Q_PENDING_VAL, &lock->val); >>> +} >>> + >>> +/** >>> * clear_pending_set_locked - take ownership and clear the pending bit. >>> * @lock: Pointer to queued spinlock structure >>> * >> BTW, there is a similar clear_pending() function in >> qspinlock_paravirt.c. I think you need to remove that with this patch. > Thanks, I'll do that. I did build and bisect this series... for arm64, which > is completely useless as it doesn't get compiled until the final patch which > I haven't posted here. > > Will
You certainly need to get a x86 system and compiles with the patches applied one-by-one with CONFIG_PARAVIRT_SPINLOCKS enabled. Cheers, Longman