From 7114aae02742d6b5c5a0d39a41deb61d415d3717 Mon Sep 17 00:00:00 2001 From: Brian King Date: Fri, 23 May 2014 10:52:11 -0500 Subject: [PATCH] ibmvscsi: Add memory barriers for send / receive 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 Acked-by: Nathan Fontenot Cc: stable@vger.kernel.org Signed-off-by: Christoph Hellwig --- drivers/scsi/ibmvscsi/ibmvscsi.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c index 9caf9a979659..7b23f21f22f1 100644 --- a/drivers/scsi/ibmvscsi/ibmvscsi.c +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c @@ -185,6 +185,11 @@ static struct viosrp_crq *crq_queue_next_crq(struct crq_queue *queue) 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 ibmvscsi_host_data *hostdata, { 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); }