[PATCH 1/2] RDMA/cxgb4: Serialize calls to cq's comp_handler by lock

[PATCH 1/2] RDMA/cxgb4: Serialize calls to cq's comp_handler by lock

[Kumar Sanghvi]

Commit 01e7da6ba53ca4d6189a1eae45607c0331c871f2 introduced a potential
problem wherein the cq's comp_handler can get called simultaneously from
different places in iw_cxgb4 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.

This problem was reported by Parav Pandit <Parav.Pandit-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org>.
Based on discussion between Parav Pandit and Steve Wise, this patch
aims to correct above problem by serializing the calls to cq's comp_handler
using a spin_lock.

Reported-by: Parav Pandit <Parav.Pandit-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Kumar Sanghvi <kumaras-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org>
---
 drivers/infiniband/hw/cxgb4/cq.c       |    1 +
 drivers/infiniband/hw/cxgb4/ev.c       |   10 ++++++++--
 drivers/infiniband/hw/cxgb4/iw_cxgb4.h |    1 +
 drivers/infiniband/hw/cxgb4/qp.c       |   15 +++++++++++++--
 4 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/hw/cxgb4/cq.c b/drivers/infiniband/hw/cxgb4/cq.c
index 901c5fb..f35a935 100644
--- a/drivers/infiniband/hw/cxgb4/cq.c
+++ b/drivers/infiniband/hw/cxgb4/cq.c
@@ -818,6 +818,7 @@ struct ib_cq *c4iw_create_cq(struct ib_device *ibdev, int entries,
 	chp->cq.size--;				/* status page */
 	chp->ibcq.cqe = entries - 2;
 	spin_lock_init(&chp->lock);
+	spin_lock_init(&chp->comp_handler_lock);
 	atomic_set(&chp->refcnt, 1);
 	init_waitqueue_head(&chp->wait);
 	ret = insert_handle(rhp, &rhp->cqidr, chp, chp->cq.cqid);
diff --git a/drivers/infiniband/hw/cxgb4/ev.c b/drivers/infiniband/hw/cxgb4/ev.c
index c13041a..397cb36 100644
--- a/drivers/infiniband/hw/cxgb4/ev.c
+++ b/drivers/infiniband/hw/cxgb4/ev.c
@@ -42,6 +42,7 @@ static void post_qp_event(struct c4iw_dev *dev, struct c4iw_cq *chp,
 {
 	struct ib_event event;
 	struct c4iw_qp_attributes attrs;
+	unsigned long flag;
 
 	if ((qhp->attr.state == C4IW_QP_STATE_ERROR) ||
 	    (qhp->attr.state == C4IW_QP_STATE_TERMINATE)) {
@@ -72,7 +73,9 @@ static void post_qp_event(struct c4iw_dev *dev, struct c4iw_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);
 }
 
 void c4iw_ev_dispatch(struct c4iw_dev *dev, struct t4_cqe *err_cqe)
@@ -183,11 +186,14 @@ out:
 int c4iw_ev_handler(struct c4iw_dev *dev, u32 qid)
 {
 	struct c4iw_cq *chp;
+	unsigned long flag;
 
 	chp = get_chp(dev, qid);
-	if (chp)
+	if (chp) {
+		spin_lock_irqsave(&chp->comp_handler_lock, flag);
 		(*chp->ibcq.comp_handler)(&chp->ibcq, chp->ibcq.cq_context);
-	else
+		spin_unlock_irqrestore(&chp->comp_handler_lock, flag);
+	} else
 		PDBG("%s unknown cqid 0x%x\n", __func__, qid);
 	return 0;
 }
diff --git a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
index 62cea0e..1357c5b 100644
--- a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
+++ b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
@@ -309,6 +309,7 @@ struct c4iw_cq {
 	struct c4iw_dev *rhp;
 	struct t4_cq cq;
 	spinlock_t lock;
+	spinlock_t comp_handler_lock;
 	atomic_t refcnt;
 	wait_queue_head_t wait;
 };
diff --git a/drivers/infiniband/hw/cxgb4/qp.c b/drivers/infiniband/hw/cxgb4/qp.c
index b59b56c..a391a4a 100644
--- a/drivers/infiniband/hw/cxgb4/qp.c
+++ b/drivers/infiniband/hw/cxgb4/qp.c
@@ -945,8 +945,11 @@ static void __flush_qp(struct c4iw_qp *qhp, struct c4iw_cq *rchp,
 	flushed = c4iw_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);
@@ -956,13 +959,17 @@ static void __flush_qp(struct c4iw_qp *qhp, struct c4iw_cq *rchp,
 	flushed = c4iw_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);
+	}
 }
 
 static void flush_qp(struct c4iw_qp *qhp)
 {
 	struct c4iw_cq *rchp, *schp;
+	unsigned long flag;
 
 	rchp = get_chp(qhp->rhp, qhp->attr.rcq);
 	schp = get_chp(qhp->rhp, qhp->attr.scq);
@@ -970,11 +977,15 @@ static void flush_qp(struct c4iw_qp *qhp)
 	if (qhp->ibqp.uobject) {
 		t4_set_wq_in_error(&qhp->wq);
 		t4_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) {
 			t4_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;
 	}
-- 
1.7.1

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[PATCH 2/2] RDMA/cxgb3: Serialize calls to cq's comp_handler by lock

[Kumar Sanghvi]

iw_cxgb3 has a potential problem wherein the 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-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org> for
iw_cxgb4 driver. Based on discussion between Parav Pandit and Steve Wise,
this patch aims to correct above problem by serializing the calls to cq's
comp_handler using a spin_lock.

Signed-off-by: Kumar Sanghvi <kumaras-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org>
---
 drivers/infiniband/hw/cxgb3/iwch_ev.c       |    6 ++++++
 drivers/infiniband/hw/cxgb3/iwch_provider.c |    1 +
 drivers/infiniband/hw/cxgb3/iwch_provider.h |    1 +
 drivers/infiniband/hw/cxgb3/iwch_qp.c       |   14 ++++++++++++--
 4 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/cxgb3/iwch_ev.c b/drivers/infiniband/hw/cxgb3/iwch_ev.c
index 71e0d84..abcc9e7 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_ev.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_ev.c
@@ -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:
diff --git a/drivers/infiniband/hw/cxgb3/iwch_provider.c b/drivers/infiniband/hw/cxgb3/iwch_provider.c
index c7d9411..37c224f 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_provider.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_provider.c
@@ -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)) {
diff --git a/drivers/infiniband/hw/cxgb3/iwch_provider.h b/drivers/infiniband/hw/cxgb3/iwch_provider.h
index 9a342c9..87c14b0 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_provider.h
+++ b/drivers/infiniband/hw/cxgb3/iwch_provider.h
@@ -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;
diff --git a/drivers/infiniband/hw/cxgb3/iwch_qp.c b/drivers/infiniband/hw/cxgb3/iwch_qp.c
index ecd313f..bea5839 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_qp.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_qp.c
@@ -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;
 	}
-- 
1.7.1

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Re: [PATCH 2/2] RDMA/cxgb3: Serialize calls to cq's comp_handler by lock

[Steve Wise]

On 10/24/2011 10:50 AM, Kumar Sanghvi wrote:
> iw_cxgb3 has a potential problem wherein the 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-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org>  for
> iw_cxgb4 driver. Based on discussion between Parav Pandit and Steve Wise,
> this patch aims to correct above problem by serializing the calls to cq's
> comp_handler using a spin_lock.
>
> Signed-off-by: Kumar Sanghvi<kumaras-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org>

Acked-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
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Re: [PATCH 1/2] RDMA/cxgb4: Serialize calls to cq's comp_handler by lock

[Steve Wise]

On 10/24/2011 10:50 AM, Kumar Sanghvi wrote:
> Commit 01e7da6ba53ca4d6189a1eae45607c0331c871f2 introduced a potential
> problem wherein the cq's comp_handler can get called simultaneously from
> different places in iw_cxgb4 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.
>
> This problem was reported by Parav Pandit<Parav.Pandit-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org>.
> Based on discussion between Parav Pandit and Steve Wise, this patch
> aims to correct above problem by serializing the calls to cq's comp_handler
> using a spin_lock.
>
> Reported-by: Parav Pandit<Parav.Pandit-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Kumar Sanghvi<kumaras-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org>

Acked-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
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