From: Brian King Date: Fri, 23 May 2014 15:52:11 +0000 (-0500) Subject: ibmvscsi: Add memory barriers for send / receive X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=c8e9b34fdc16b7f568237d54002f1f292103b15f;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git ibmvscsi: Add memory barriers for send / receive 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 Acked-by: Nathan Fontenot Signed-off-by: Christoph Hellwig Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c index 1e29efc8271a..c62b3e5d44bd 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); }