Patch "iw_cxgb4: atomically flush the qp" has been added to the 4.14-stable tree

Patch "iw_cxgb4: atomically flush the qp" has been added to the 4.14-stable tree

[gregkh]

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

    iw_cxgb4: atomically flush the qp

to the 4.14-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:
     iw_cxgb4-atomically-flush-the-qp.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From bc52e9ca74b9a395897bb640c6671b2cbf716032 Mon Sep 17 00:00:00 2001
From: Steve Wise <swise@opengridcomputing.com>
Date: Thu, 9 Nov 2017 07:21:26 -0800
Subject: iw_cxgb4: atomically flush the qp

From: Steve Wise <swise@opengridcomputing.com>

commit bc52e9ca74b9a395897bb640c6671b2cbf716032 upstream.

__flush_qp() has a race condition where during the flush operation,
the qp lock is released allowing another thread to possibly post a WR,
which corrupts the queue state, possibly causing crashes.  The lock was
released to preserve the cq/qp locking hierarchy of cq first, then qp.
However releasing the qp lock is not necessary; both RQ and SQ CQ locks
can be acquired first, followed by the qp lock, and then the RQ and SQ
flushing can be done w/o unlocking.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/infiniband/hw/cxgb4/qp.c |   19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

--- a/drivers/infiniband/hw/cxgb4/qp.c
+++ b/drivers/infiniband/hw/cxgb4/qp.c
@@ -1271,31 +1271,34 @@ static void __flush_qp(struct c4iw_qp *q
 
 	pr_debug("%s qhp %p rchp %p schp %p\n", __func__, qhp, rchp, schp);
 
-	/* locking hierarchy: cq lock first, then qp lock. */
+	/* locking hierarchy: cqs lock first, then qp lock. */
 	spin_lock_irqsave(&rchp->lock, flag);
+	if (schp != rchp)
+		spin_lock(&schp->lock);
 	spin_lock(&qhp->lock);
 
 	if (qhp->wq.flushed) {
 		spin_unlock(&qhp->lock);
+		if (schp != rchp)
+			spin_unlock(&schp->lock);
 		spin_unlock_irqrestore(&rchp->lock, flag);
 		return;
 	}
 	qhp->wq.flushed = 1;
+	t4_set_wq_in_error(&qhp->wq);
 
 	c4iw_flush_hw_cq(rchp);
 	c4iw_count_rcqes(&rchp->cq, &qhp->wq, &count);
 	rq_flushed = c4iw_flush_rq(&qhp->wq, &rchp->cq, count);
-	spin_unlock(&qhp->lock);
-	spin_unlock_irqrestore(&rchp->lock, flag);
 
-	/* locking hierarchy: cq lock first, then qp lock. */
-	spin_lock_irqsave(&schp->lock, flag);
-	spin_lock(&qhp->lock);
 	if (schp != rchp)
 		c4iw_flush_hw_cq(schp);
 	sq_flushed = c4iw_flush_sq(qhp);
+
 	spin_unlock(&qhp->lock);
-	spin_unlock_irqrestore(&schp->lock, flag);
+	if (schp != rchp)
+		spin_unlock(&schp->lock);
+	spin_unlock_irqrestore(&rchp->lock, flag);
 
 	if (schp == rchp) {
 		if (t4_clear_cq_armed(&rchp->cq) &&
@@ -1329,8 +1332,8 @@ static void flush_qp(struct c4iw_qp *qhp
 	rchp = to_c4iw_cq(qhp->ibqp.recv_cq);
 	schp = to_c4iw_cq(qhp->ibqp.send_cq);
 
-	t4_set_wq_in_error(&qhp->wq);
 	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);


Patches currently in stable-queue which might be from swise@opengridcomputing.com are

queue-4.14/iw_cxgb4-only-clear-the-armed-bit-if-a-notification-is-needed.patch
queue-4.14/iw_cxgb4-atomically-flush-the-qp.patch
queue-4.14/iw_cxgb4-when-flushing-complete-all-wrs-in-a-chain.patch
queue-4.14/iw_cxgb4-reflect-the-original-wr-opcode-in-drain-cqes.patch
queue-4.14/iw_cxgb4-only-call-the-cq-comp_handler-when-the-cq-is-armed.patch