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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