IB/qib: Remove atomic_inc_not_zero() from QP RCU
Follow Documentation/RCU/rcuref.txt guidance in removing
atomic_inc_not_zero() from QP RCU implementation.
This patch also removes an unneeded synchronize_rcu() in the add path.
Reviewed-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/hw/qib/qib_qp.c b/drivers/infiniband/hw/qib/qib_qp.c
index a6a2cc2..c1f573a 100644
--- a/drivers/infiniband/hw/qib/qib_qp.c
+++ b/drivers/infiniband/hw/qib/qib_qp.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012 Intel Corporation. All rights reserved.
+ * Copyright (c) 2012, 2013 Intel Corporation. All rights reserved.
* Copyright (c) 2006 - 2012 QLogic Corporation. * All rights reserved.
* Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
*
@@ -222,8 +222,8 @@
unsigned long flags;
unsigned n = qpn_hash(dev, qp->ibqp.qp_num);
- spin_lock_irqsave(&dev->qpt_lock, flags);
atomic_inc(&qp->refcount);
+ spin_lock_irqsave(&dev->qpt_lock, flags);
if (qp->ibqp.qp_num == 0)
rcu_assign_pointer(ibp->qp0, qp);
@@ -235,7 +235,6 @@
}
spin_unlock_irqrestore(&dev->qpt_lock, flags);
- synchronize_rcu();
}
/*
@@ -247,36 +246,39 @@
struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
unsigned n = qpn_hash(dev, qp->ibqp.qp_num);
unsigned long flags;
+ int removed = 1;
spin_lock_irqsave(&dev->qpt_lock, flags);
if (rcu_dereference_protected(ibp->qp0,
lockdep_is_held(&dev->qpt_lock)) == qp) {
- atomic_dec(&qp->refcount);
rcu_assign_pointer(ibp->qp0, NULL);
} else if (rcu_dereference_protected(ibp->qp1,
lockdep_is_held(&dev->qpt_lock)) == qp) {
- atomic_dec(&qp->refcount);
rcu_assign_pointer(ibp->qp1, NULL);
} else {
struct qib_qp *q;
struct qib_qp __rcu **qpp;
+ removed = 0;
qpp = &dev->qp_table[n];
for (; (q = rcu_dereference_protected(*qpp,
lockdep_is_held(&dev->qpt_lock))) != NULL;
qpp = &q->next)
if (q == qp) {
- atomic_dec(&qp->refcount);
rcu_assign_pointer(*qpp,
rcu_dereference_protected(qp->next,
lockdep_is_held(&dev->qpt_lock)));
+ removed = 1;
break;
}
}
spin_unlock_irqrestore(&dev->qpt_lock, flags);
- synchronize_rcu();
+ if (removed) {
+ synchronize_rcu();
+ atomic_dec(&qp->refcount);
+ }
}
/**
@@ -334,26 +336,25 @@
{
struct qib_qp *qp = NULL;
+ rcu_read_lock();
if (unlikely(qpn <= 1)) {
- rcu_read_lock();
if (qpn == 0)
qp = rcu_dereference(ibp->qp0);
else
qp = rcu_dereference(ibp->qp1);
+ if (qp)
+ atomic_inc(&qp->refcount);
} else {
struct qib_ibdev *dev = &ppd_from_ibp(ibp)->dd->verbs_dev;
unsigned n = qpn_hash(dev, qpn);
- rcu_read_lock();
for (qp = rcu_dereference(dev->qp_table[n]); qp;
qp = rcu_dereference(qp->next))
- if (qp->ibqp.qp_num == qpn)
+ if (qp->ibqp.qp_num == qpn) {
+ atomic_inc(&qp->refcount);
break;
+ }
}
- if (qp)
- if (unlikely(!atomic_inc_not_zero(&qp->refcount)))
- qp = NULL;
-
rcu_read_unlock();
return qp;
}