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Commit f7cf9a61 authored by Mike Marciniszyn's avatar Mike Marciniszyn Committed by Roland Dreier
Browse files

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: default avatarDean Luick <dean.luick@intel.com>
Signed-off-by: default avatarMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
parent 8469ba39

drivers/infiniband/hw/qib/qib_qp.c

+15 −14
Original line number Diff line number Diff line 
/*

 * 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 @@ static void insert_qp(struct qib_ibdev *dev, struct qib_qp *qp) 
	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 @@ static void insert_qp(struct qib_ibdev *dev, struct qib_qp *qp) 
	}



	spin_unlock_irqrestore(&dev->qpt_lock, flags);

	synchronize_rcu();

}



/*
@@ -247,36 +246,39 @@ static void remove_qp(struct qib_ibdev *dev, struct qib_qp *qp) 
	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);

	if (removed) {

		synchronize_rcu();

		atomic_dec(&qp->refcount);

	}

}



/**
@@ -334,26 +336,25 @@ struct qib_qp *qib_lookup_qpn(struct qib_ibport *ibp, u32 qpn) 
{

	struct qib_qp *qp = NULL;



	if (unlikely(qpn <= 1)) {

	rcu_read_lock();

	if (unlikely(qpn <= 1)) {

		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;

}