Patch "IB/hfi1: Fix hard lockup due to not using save/restore spin lock" 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 hard lockup due to not using save/restore spin lock

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-hard-lockup-due-to-not-using-save-restore-spin-lock.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: Tue, 24 May 2016 12:50:23 -0700
Subject: IB/hfi1: Fix hard lockup due to not using save/restore spin lock

From: Mike Marciniszyn <[email protected]>

commit 7049de65c9e520886f06d6f9deceaaed5d93fb7c upstream.

Commit b9b06cb6feda
("IB/hfi1: Fix missing lock/unlock in verbs drain callback") added a spin lock.

Unfortunately, the new lock code can be called from a base level interrupt state, and an interrupt that can get stacked will attempt to get the same lock.

Fix by using the flag save/restore spin lock variation.

---
 drivers/staging/rdma/hfi1/qp.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

@@ -512,6 +512,7 @@ static void iowait_wakeup(struct iowait
 static void iowait_sdma_drained(struct iowait *wait)
 {
 	struct rvt_qp *qp = iowait_to_qp(wait);
+	unsigned long flags;
 
 	/*
 	 * This happens when the send engine notes

@@ -519,12 +520,12 @@ static void iowait_sdma_drained(struct i
 	 * do the flush work until that QP's
 	 * sdma work has finished.
 	 */
-	spin_lock(&qp->s_lock);
+	spin_lock_irqsave(&qp->s_lock, flags);
 	if (qp->s_flags & RVT_S_WAIT_DMA) {
 		qp->s_flags &= ~RVT_S_WAIT_DMA;
 		hfi1_schedule_send(qp);
 	}
-	spin_unlock(&qp->s_lock);
+	spin_unlock_irqrestore(&qp->s_lock, flags);
 }
 
 /**

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

queue-4.6/ib-hfi1-fix-hard-lockup-due-to-not-using-save-restore-spin-lock.patch