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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 <brking@linux.vnet.ibm.com>
Acked-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Brian King 2014-05-23 10:52:11 -05:00 committed by Christoph Hellwig
parent 9ee755974b
commit 7114aae027
1 changed files with 10 additions and 0 deletions
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10
drivers/scsi/ibmvscsi/ibmvscsi.c
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@ -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);
}