[PATCH 4/5] Remove cpu_relax_lowlatency users

[Christian Borntraeger]

With the s390 special case of a yielding cpu_relax implementation gone,
we can now remove all users of cpu_relax_lowlatency.

Signed-off-by: Christian Borntraeger <borntraeger at de.ibm.com>
---
 drivers/gpu/drm/i915/i915_gem_request.c | 2 +-
 drivers/vhost/net.c                     | 4 ++--
 kernel/locking/mcs_spinlock.h           | 4 ++--
 kernel/locking/mutex.c                  | 4 ++--
 kernel/locking/osq_lock.c               | 6 +++---
 kernel/locking/qrwlock.c                | 6 +++---
 kernel/locking/rwsem-xadd.c             | 4 ++--
 lib/lockref.c                           | 2 +-
 8 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 8832f8e..383d134 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -723,7 +723,7 @@ bool __i915_spin_request(const struct drm_i915_gem_request *req,
 		if (busywait_stop(timeout_us, cpu))
 			break;
 
-		cpu_relax_lowlatency();
+		cpu_relax();
 	} while (!need_resched());
 
 	return false;
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 5dc128a..5dc3465 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -342,7 +342,7 @@ static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
 		endtime = busy_clock() + vq->busyloop_timeout;
 		while (vhost_can_busy_poll(vq->dev, endtime) &&
 		       vhost_vq_avail_empty(vq->dev, vq))
-			cpu_relax_lowlatency();
+			cpu_relax();
 		preempt_enable();
 		r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
 				      out_num, in_num, NULL, NULL);
@@ -533,7 +533,7 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk)
 		while (vhost_can_busy_poll(&net->dev, endtime) &&
 		       !sk_has_rx_data(sk) &&
 		       vhost_vq_avail_empty(&net->dev, vq))
-			cpu_relax_lowlatency();
+			cpu_relax();
 
 		preempt_enable();
 
diff --git a/kernel/locking/mcs_spinlock.h b/kernel/locking/mcs_spinlock.h
index c835270..6a385aa 100644
--- a/kernel/locking/mcs_spinlock.h
+++ b/kernel/locking/mcs_spinlock.h
@@ -28,7 +28,7 @@ struct mcs_spinlock {
 #define arch_mcs_spin_lock_contended(l)					\
 do {									\
 	while (!(smp_load_acquire(l)))					\
-		cpu_relax_lowlatency();					\
+		cpu_relax();						\
 } while (0)
 #endif
 
@@ -108,7 +108,7 @@ void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 			return;
 		/* Wait until the next pointer is set */
 		while (!(next = READ_ONCE(node->next)))
-			cpu_relax_lowlatency();
+			cpu_relax();
 	}
 
 	/* Pass lock to next waiter. */
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index a70b90d..4463405 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -241,7 +241,7 @@ bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
 			break;
 		}
 
-		cpu_relax_lowlatency();
+		cpu_relax();
 	}
 	rcu_read_unlock();
 
@@ -377,7 +377,7 @@ static bool mutex_optimistic_spin(struct mutex *lock,
 		 * memory barriers as we'll eventually observe the right
 		 * values at the cost of a few extra spins.
 		 */
-		cpu_relax_lowlatency();
+		cpu_relax();
 	}
 
 	osq_unlock(&lock->osq);
diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c
index 05a3785..4ea2710 100644
--- a/kernel/locking/osq_lock.c
+++ b/kernel/locking/osq_lock.c
@@ -75,7 +75,7 @@ osq_wait_next(struct optimistic_spin_queue *lock,
 				break;
 		}
 
-		cpu_relax_lowlatency();
+		cpu_relax();
 	}
 
 	return next;
@@ -122,7 +122,7 @@ bool osq_lock(struct optimistic_spin_queue *lock)
 		if (need_resched())
 			goto unqueue;
 
-		cpu_relax_lowlatency();
+		cpu_relax();
 	}
 	return true;
 
@@ -148,7 +148,7 @@ bool osq_lock(struct optimistic_spin_queue *lock)
 		if (smp_load_acquire(&node->locked))
 			return true;
 
-		cpu_relax_lowlatency();
+		cpu_relax();
 
 		/*
 		 * Or we race against a concurrent unqueue()'s step-B, in which
diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c
index 19248dd..cc3ed0c 100644
--- a/kernel/locking/qrwlock.c
+++ b/kernel/locking/qrwlock.c
@@ -54,7 +54,7 @@ static __always_inline void
 rspin_until_writer_unlock(struct qrwlock *lock, u32 cnts)
 {
 	while ((cnts & _QW_WMASK) == _QW_LOCKED) {
-		cpu_relax_lowlatency();
+		cpu_relax();
 		cnts = atomic_read_acquire(&lock->cnts);
 	}
 }
@@ -130,7 +130,7 @@ void queued_write_lock_slowpath(struct qrwlock *lock)
 		   (cmpxchg_relaxed(&l->wmode, 0, _QW_WAITING) == 0))
 			break;
 
-		cpu_relax_lowlatency();
+		cpu_relax();
 	}
 
 	/* When no more readers, set the locked flag */
@@ -141,7 +141,7 @@ void queued_write_lock_slowpath(struct qrwlock *lock)
 					    _QW_LOCKED) == _QW_WAITING))
 			break;
 
-		cpu_relax_lowlatency();
+		cpu_relax();
 	}
 unlock:
 	arch_spin_unlock(&lock->wait_lock);
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 2337b4b..2fa2e2e6 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -368,7 +368,7 @@ static noinline bool rwsem_spin_on_owner(struct rw_semaphore *sem)
 			return false;
 		}
 
-		cpu_relax_lowlatency();
+		cpu_relax();
 	}
 	rcu_read_unlock();
 out:
@@ -423,7 +423,7 @@ static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
 		 * memory barriers as we'll eventually observe the right
 		 * values at the cost of a few extra spins.
 		 */
-		cpu_relax_lowlatency();
+		cpu_relax();
 	}
 	osq_unlock(&sem->osq);
 done:
diff --git a/lib/lockref.c b/lib/lockref.c
index 5a92189..c4bfcb8 100644
--- a/lib/lockref.c
+++ b/lib/lockref.c
@@ -20,7 +20,7 @@
 		if (likely(old.lock_count == prev.lock_count)) {		\
 			SUCCESS;						\
 		}								\
-		cpu_relax_lowlatency();						\
+		cpu_relax();							\
 	}									\
 } while (0)
 
-- 
2.5.5