Hi Waiman, On Thu, Apr 26, 2018 at 04:16:30PM -0400, Waiman Long wrote: > On 04/26/2018 06:34 AM, Will Deacon wrote: > > diff --git a/kernel/locking/qspinlock_paravirt.h > > b/kernel/locking/qspinlock_paravirt.h > > index 2711940429f5..2dbad2f25480 100644 > > --- a/kernel/locking/qspinlock_paravirt.h > > +++ b/kernel/locking/qspinlock_paravirt.h > > @@ -118,11 +118,6 @@ static __always_inline void set_pending(struct > > qspinlock *lock) > > WRITE_ONCE(lock->pending, 1); > > } > > > > -static __always_inline void clear_pending(struct qspinlock *lock) > > -{ > > - WRITE_ONCE(lock->pending, 0); > > -} > > - > > /* > > * The pending bit check in pv_queued_spin_steal_lock() isn't a memory > > * barrier. Therefore, an atomic cmpxchg_acquire() is used to acquire the > > There is another clear_pending() function after the "#else /* > _Q_PENDING_BITS == 8 */" line that need to be removed as well.
Bugger, sorry I missed that one. Is the >= 16K CPUs case supported elsewhere in Linux? The x86 Kconfig appears to clamp NR_CPUS to 8192 iiuc. Anyway, additional patch below. Ingo -- please can you apply this on top? Thanks, Will --->8 >From ef6aa51e47047fe1a57dfdbe2f45caf63fa95be4 Mon Sep 17 00:00:00 2001 From: Will Deacon <will.dea...@arm.com> Date: Fri, 27 Apr 2018 10:40:13 +0100 Subject: [PATCH] locking/qspinlock: Remove duplicate clear_pending function from PV code The native clear_pending function is identical to the PV version, so the latter can simply be removed. This fixes the build for systems with >= 16K CPUs using the PV lock implementation. Cc: Ingo Molnar <mi...@kernel.org> Cc: Peter Zijlstra <pet...@infradead.org> Reported-by: Waiman Long <long...@redhat.com> Signed-off-by: Will Deacon <will.dea...@arm.com> --- kernel/locking/qspinlock_paravirt.h | 5 ----- 1 file changed, 5 deletions(-) diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h index 25730b2ac022..5a0cf5f9008c 100644 --- a/kernel/locking/qspinlock_paravirt.h +++ b/kernel/locking/qspinlock_paravirt.h @@ -130,11 +130,6 @@ static __always_inline void set_pending(struct qspinlock *lock) atomic_or(_Q_PENDING_VAL, &lock->val); } -static __always_inline void clear_pending(struct qspinlock *lock) -{ - atomic_andnot(_Q_PENDING_VAL, &lock->val); -} - static __always_inline int trylock_clear_pending(struct qspinlock *lock) { int val = atomic_read(&lock->val); -- 2.1.4