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Commit f7cc25d0 authored by Kumar Sanghvi's avatar Kumar Sanghvi Committed by Roland Dreier
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RDMA/cxgb3: Serialize calls to CQ's comp_handler 



iw_cxgb3 has a potential problem where a CQ's comp_handler can get
called simultaneously from different places in iw_cxgb3 driver.  This
does not comply with Documentation/infiniband/core_locking.txt, which
states that at a given point of time, there should be only one
callback per CQ should be active.

Such problem was reported by Parav Pandit <Parav.Pandit@Emulex.Com>
for iw_cxgb4 driver.  Based on discussion between Parav Pandit and
Steve Wise, this patch fixes the above problem by serializing the
calls to a CQ's comp_handler using a spin_lock.

Signed-off-by: default avatarKumar Sanghvi <kumaras@chelsio.com>
Acked-by: default avatarSteve Wise <swise@opengridcomputing.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
parent 976d1676

drivers/infiniband/hw/cxgb3/iwch_ev.c

+6 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ static void post_qp_event(struct iwch_dev *rnicp, struct iwch_cq *chp, 
	struct ib_event event;

	struct iwch_qp_attributes attrs;

	struct iwch_qp *qhp;

	unsigned long flag;



	spin_lock(&rnicp->lock);

	qhp = get_qhp(rnicp, CQE_QPID(rsp_msg->cqe));
@@ -94,7 +95,9 @@ static void post_qp_event(struct iwch_dev *rnicp, struct iwch_cq *chp, 
	if (qhp->ibqp.event_handler)

		(*qhp->ibqp.event_handler)(&event, qhp->ibqp.qp_context);



	spin_lock_irqsave(&chp->comp_handler_lock, flag);

	(*chp->ibcq.comp_handler)(&chp->ibcq, chp->ibcq.cq_context);

	spin_unlock_irqrestore(&chp->comp_handler_lock, flag);



	if (atomic_dec_and_test(&qhp->refcnt))

		wake_up(&qhp->wait);
@@ -107,6 +110,7 @@ void iwch_ev_dispatch(struct cxio_rdev *rdev_p, struct sk_buff *skb) 
	struct iwch_cq *chp;

	struct iwch_qp *qhp;

	u32 cqid = RSPQ_CQID(rsp_msg);

	unsigned long flag;



	rnicp = (struct iwch_dev *) rdev_p->ulp;

	spin_lock(&rnicp->lock);
@@ -170,7 +174,9 @@ void iwch_ev_dispatch(struct cxio_rdev *rdev_p, struct sk_buff *skb) 
		 */

		if (qhp->ep && SQ_TYPE(rsp_msg->cqe))

			dst_confirm(qhp->ep->dst);

		spin_lock_irqsave(&chp->comp_handler_lock, flag);

		(*chp->ibcq.comp_handler)(&chp->ibcq, chp->ibcq.cq_context);

		spin_unlock_irqrestore(&chp->comp_handler_lock, flag);

		break;



	case TPT_ERR_STAG:

drivers/infiniband/hw/cxgb3/iwch_provider.c

+1 −0
Original line number Diff line number Diff line
@@ -190,6 +190,7 @@ static struct ib_cq *iwch_create_cq(struct ib_device *ibdev, int entries, int ve 
	chp->rhp = rhp;

	chp->ibcq.cqe = 1 << chp->cq.size_log2;

	spin_lock_init(&chp->lock);

	spin_lock_init(&chp->comp_handler_lock);

	atomic_set(&chp->refcnt, 1);

	init_waitqueue_head(&chp->wait);

	if (insert_handle(rhp, &rhp->cqidr, chp, chp->cq.cqid)) {

drivers/infiniband/hw/cxgb3/iwch_provider.h

+1 −0
Original line number Diff line number Diff line
@@ -103,6 +103,7 @@ struct iwch_cq { 
	struct iwch_dev *rhp;

	struct t3_cq cq;

	spinlock_t lock;

	spinlock_t comp_handler_lock;

	atomic_t refcnt;

	wait_queue_head_t wait;

	u32 __user *user_rptr_addr;

drivers/infiniband/hw/cxgb3/iwch_qp.c

+12 −2
Original line number Diff line number Diff line
@@ -822,8 +822,11 @@ static void __flush_qp(struct iwch_qp *qhp, struct iwch_cq *rchp, 
	flushed = cxio_flush_rq(&qhp->wq, &rchp->cq, count);

	spin_unlock(&qhp->lock);

	spin_unlock_irqrestore(&rchp->lock, *flag);

	if (flushed)

	if (flushed) {

		spin_lock_irqsave(&rchp->comp_handler_lock, *flag);

		(*rchp->ibcq.comp_handler)(&rchp->ibcq, rchp->ibcq.cq_context);

		spin_unlock_irqrestore(&rchp->comp_handler_lock, *flag);

	}



	/* locking hierarchy: cq lock first, then qp lock. */

	spin_lock_irqsave(&schp->lock, *flag);
@@ -833,8 +836,11 @@ static void __flush_qp(struct iwch_qp *qhp, struct iwch_cq *rchp, 
	flushed = cxio_flush_sq(&qhp->wq, &schp->cq, count);

	spin_unlock(&qhp->lock);

	spin_unlock_irqrestore(&schp->lock, *flag);

	if (flushed)

	if (flushed) {

		spin_lock_irqsave(&schp->comp_handler_lock, *flag);

		(*schp->ibcq.comp_handler)(&schp->ibcq, schp->ibcq.cq_context);

		spin_unlock_irqrestore(&schp->comp_handler_lock, *flag);

	}



	/* deref */

	if (atomic_dec_and_test(&qhp->refcnt))
@@ -853,11 +859,15 @@ static void flush_qp(struct iwch_qp *qhp, unsigned long *flag) 
	if (qhp->ibqp.uobject) {

		cxio_set_wq_in_error(&qhp->wq);

		cxio_set_cq_in_error(&rchp->cq);

		spin_lock_irqsave(&rchp->comp_handler_lock, *flag);

		(*rchp->ibcq.comp_handler)(&rchp->ibcq, rchp->ibcq.cq_context);

		spin_unlock_irqrestore(&rchp->comp_handler_lock, *flag);

		if (schp != rchp) {

			cxio_set_cq_in_error(&schp->cq);

			spin_lock_irqsave(&schp->comp_handler_lock, *flag);

			(*schp->ibcq.comp_handler)(&schp->ibcq,

						   schp->ibcq.cq_context);

			spin_unlock_irqrestore(&schp->comp_handler_lock, *flag);

		}

		return;

	}