Ensure that received Command-Response Queue (CRQ) entries are
properly read/written in order by the driver. dma_rmb barrier
has been added before accessing the CRQ descriptor to ensure
the entire descriptor is read before processing. dma_wmb barrier
is also added to ensure the entire descriptor is written before
future processing.

Fixes: 032c5e82847a ("Driver for IBM System i/p VNIC protocol")
Signed-off-by: Lijun Pan <l...@linux.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c 
b/drivers/net/ethernet/ibm/ibmvnic.c
index 933e8fb71a8b..e947eb068163 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -5090,8 +5090,20 @@ static void ibmvnic_tasklet(struct tasklet_struct *t)
        while (!done) {
                /* Pull all the valid messages off the CRQ */
                while ((crq = ibmvnic_next_crq(adapter)) != NULL) {
+                       /* Ensure that the entire CRQ descriptor queue->msgs
+                        * has been loaded before reading its contents.
+                        * This barrier makes sure ibmvnic_next_crq()'s
+                        * crq->generic.first & IBMVNIC_CRQ_CMD_RSP is loaded
+                        * before ibmvnic_handle_crq()'s
+                        * switch(gen_crq->first) and switch(gen_crq->cmd).
+                        */
+                       dma_rmb();
                        ibmvnic_handle_crq(crq, adapter);
                        crq->generic.first = 0;
+                       /* Ensure the entire CRQ descriptor is written before
+                        * future writing.
+                        */
+                       dma_wmb();
                }
 
                /* remain in tasklet until all
-- 
2.23.0

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