[PATCH 2/7] IB/rxe: Disable completion upcalls when a CQ is destroyed

[Andrew Boyer <andrew.boyer@xxxxxxxx>]

This prevents the stack from accessing userspace objects while they
are being torn down.

Fixes: 8700e3e7c485 ("Soft RoCE driver")
Signed-off-by: Andrew Boyer <andrew.boyer@xxxxxxxx>
---
 drivers/infiniband/sw/rxe/rxe_cq.c    | 19 +++++++++++++++++++
 drivers/infiniband/sw/rxe/rxe_loc.h   |  2 ++
 drivers/infiniband/sw/rxe/rxe_verbs.c |  2 ++
 drivers/infiniband/sw/rxe/rxe_verbs.h |  1 +
 4 files changed, 24 insertions(+)

diff --git a/drivers/infiniband/sw/rxe/rxe_cq.c b/drivers/infiniband/sw/rxe/rxe_cq.c
index 49fe42c..c4aabf7 100644
--- a/drivers/infiniband/sw/rxe/rxe_cq.c
+++ b/drivers/infiniband/sw/rxe/rxe_cq.c
@@ -69,6 +69,14 @@ int rxe_cq_chk_attr(struct rxe_dev *rxe, struct rxe_cq *cq,
 static void rxe_send_complete(unsigned long data)
 {
 	struct rxe_cq *cq = (struct rxe_cq *)data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cq->cq_lock, flags);
+	if (cq->is_dying) {
+		spin_unlock_irqrestore(&cq->cq_lock, flags);
+		return;
+	}
+	spin_unlock_irqrestore(&cq->cq_lock, flags);
 
 	cq->ibcq.comp_handler(&cq->ibcq, cq->ibcq.cq_context);
 }
@@ -97,6 +105,8 @@ int rxe_cq_from_init(struct rxe_dev *rxe, struct rxe_cq *cq, int cqe,
 	if (udata)
 		cq->is_user = 1;
 
+	cq->is_dying = false;
+
 	tasklet_init(&cq->comp_task, rxe_send_complete, (unsigned long)cq);
 
 	spin_lock_init(&cq->cq_lock);
@@ -156,6 +166,15 @@ int rxe_cq_post(struct rxe_cq *cq, struct rxe_cqe *cqe, int solicited)
 	return 0;
 }
 
+void rxe_cq_disable(struct rxe_cq *cq)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&cq->cq_lock, flags);
+	cq->is_dying = true;
+	spin_unlock_irqrestore(&cq->cq_lock, flags);
+}
+
 void rxe_cq_cleanup(struct rxe_pool_entry *arg)
 {
 	struct rxe_cq *cq = container_of(arg, typeof(*cq), pelem);
diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
index d6299ed..64f8fa1 100644
--- a/drivers/infiniband/sw/rxe/rxe_loc.h
+++ b/drivers/infiniband/sw/rxe/rxe_loc.h
@@ -64,6 +64,8 @@ int rxe_cq_from_init(struct rxe_dev *rxe, struct rxe_cq *cq, int cqe,
 
 int rxe_cq_post(struct rxe_cq *cq, struct rxe_cqe *cqe, int solicited);
 
+void rxe_cq_disable(struct rxe_cq *cq);
+
 void rxe_cq_cleanup(struct rxe_pool_entry *arg);
 
 /* rxe_mcast.c */
diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
index af90a7d..02a39e8 100644
--- a/drivers/infiniband/sw/rxe/rxe_verbs.c
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
@@ -960,6 +960,8 @@ static int rxe_destroy_cq(struct ib_cq *ibcq)
 {
 	struct rxe_cq *cq = to_rcq(ibcq);
 
+	rxe_cq_disable(cq);
+
 	rxe_drop_ref(cq);
 	return 0;
 }
diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h
index 5a180fb..b09a9e2 100644
--- a/drivers/infiniband/sw/rxe/rxe_verbs.h
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.h
@@ -89,6 +89,7 @@ struct rxe_cq {
 	struct rxe_queue	*queue;
 	spinlock_t		cq_lock;
 	u8			notify;
+	bool			is_dying;
 	int			is_user;
 	struct tasklet_struct	comp_task;
 };
-- 
1.8.3.1

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