[PATCH 4/5] Remove cpu_relax_lowlatency users

Christian Borntraeger
2016-10-21T12:00:05Z

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@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