Patch "ibmvscsi: Add memory barriers for send / receive" has been added to the 3.15-stable tree

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

    ibmvscsi: Add memory barriers for send / receive

to the 3.15-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:
     ibmvscsi-add-memory-barriers-for-send-receive.patch
and it can be found in the queue-3.15 subdirectory.

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


>From 7114aae02742d6b5c5a0d39a41deb61d415d3717 Mon Sep 17 00:00:00 2001
From: Brian King <brking@xxxxxxxxxxxxxxxxxx>
Date: Fri, 23 May 2014 10:52:11 -0500
Subject: ibmvscsi: Add memory barriers for send / receive

From: Brian King <brking@xxxxxxxxxxxxxxxxxx>

commit 7114aae02742d6b5c5a0d39a41deb61d415d3717 upstream.

Add a memory barrier prior to sending a new command to the VIOS
to ensure the VIOS does not receive stale data in the command buffer.
Also add a memory barrier when processing the CRQ for completed commands.

Signed-off-by: Brian King <brking@xxxxxxxxxxxxxxxxxx>
Acked-by: Nathan Fontenot <nfont@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/scsi/ibmvscsi/ibmvscsi.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -185,6 +185,11 @@ static struct viosrp_crq *crq_queue_next
 	if (crq->valid & 0x80) {
 		if (++queue->cur == queue->size)
 			queue->cur = 0;
+
+		/* Ensure the read of the valid bit occurs before reading any
+		 * other bits of the CRQ entry
+		 */
+		rmb();
 	} else
 		crq = NULL;
 	spin_unlock_irqrestore(&queue->lock, flags);
@@ -203,6 +208,11 @@ static int ibmvscsi_send_crq(struct ibmv
 {
 	struct vio_dev *vdev = to_vio_dev(hostdata->dev);
 
+	/*
+	 * Ensure the command buffer is flushed to memory before handing it
+	 * over to the VIOS to prevent it from fetching any stale data.
+	 */
+	mb();
 	return plpar_hcall_norets(H_SEND_CRQ, vdev->unit_address, word1, word2);
 }
 


Patches currently in stable-queue which might be from brking@xxxxxxxxxxxxxxxxxx are

queue-3.15/ibmvscsi-abort-init-sequence-during-error-recovery.patch
queue-3.15/ibmvscsi-add-memory-barriers-for-send-receive.patch
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