Patch "IB/hfi1: Fix deadlock with txreq allocation slow path" has been added to the 4.6-stable tree

This is a note to let you know that I've just added the patch titled

IB/hfi1: Fix deadlock with txreq allocation slow path

to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ib-hfi1-fix-deadlock-with-txreq-allocation-slow-path.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Mike Marciniszyn <[email protected]>
Date: Fri, 17 Jun 2016 19:17:49 -0700
Subject: IB/hfi1: Fix deadlock with txreq allocation slow path

From: Mike Marciniszyn <[email protected]>

commit 2aee309d3e01447c55fdf89cef05a0e2be372655 upstream.

A failure in the get_txreq() inline will result in a slow path retry using __get_txreq().

__get_txreq() attempts to procure the qp s_lock, which is already held in all callers.

Fix by deleting the s_lock maintenance in __get_txreq() and add sparse syntax hooks to future proof the code.

---
 drivers/staging/rdma/hfi1/verbs_txreq.c |    4 +---
 drivers/staging/rdma/hfi1/verbs_txreq.h |    1 +
 2 files changed, 2 insertions(+), 3 deletions(-)

@@ -92,11 +92,10 @@ void hfi1_put_txreq(struct verbs_txreq *
 
 struct verbs_txreq *__get_txreq(struct hfi1_ibdev *dev,
 				struct rvt_qp *qp)
+	__must_hold(&qp->s_lock)
 {
 	struct verbs_txreq *tx = ERR_PTR(-EBUSY);
-	unsigned long flags;
 
-	spin_lock_irqsave(&qp->s_lock, flags);
 	write_seqlock(&dev->iowait_lock);
 	if (ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK) {
 		struct hfi1_qp_priv *priv;

@@ -116,7 +115,6 @@ struct verbs_txreq *__get_txreq(struct h
 	}
 out:
 	write_sequnlock(&dev->iowait_lock);
-	spin_unlock_irqrestore(&qp->s_lock, flags);
 	return tx;
 }
 

@@ -73,6 +73,7 @@ struct verbs_txreq *__get_txreq(struct h
 
 static inline struct verbs_txreq *get_txreq(struct hfi1_ibdev *dev,
 					    struct rvt_qp *qp)
+	__must_hold(&qp->slock)
 {
 	struct verbs_txreq *tx;
 	struct hfi1_qp_priv *priv = qp->priv;

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/ib-hfi1-correct-issues-with-sc5-computation.patch queue-4.6/ib-hfi1-fix-deadlock-with-txreq-allocation-slow-path.patch