netdev - [PATCH net-next 01/12] ibmvnic: Ensure that subCRQ entry reads are ordered

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Message-Id: <1605208207-1896-2-git-send-email-tlfalcon@linux.ibm.com>
Date:   Thu, 12 Nov 2020 13:09:56 -0600
From:   Thomas Falcon <tlfalcon@...ux.ibm.com>
To:     netdev@...r.kernel.org
Cc:     linuxppc-dev@...ts.ozlabs.org, dnbanerg@...ibm.com,
        brking@...ux.vnet.ibm.com, pradeep@...ibm.com,
        drt@...ux.vnet.ibm.com, sukadev@...ux.vnet.ibm.com,
        ljp@...ux.vnet.ibm.com, cforno12@...ux.ibm.com,
        tlfalcon@...ux.ibm.com, ricklind@...ux.ibm.com
Subject: [PATCH net-next 01/12] ibmvnic: Ensure that subCRQ entry reads are ordered

Ensure that received Subordinate Command-Response Queue
entries are properly read in order by the driver.

Signed-off-by: Thomas Falcon <tlfalcon@...ux.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index da15913879f8..5647f54bf387 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -2391,6 +2391,8 @@ static int ibmvnic_poll(struct napi_struct *napi, int budget)
 
 		if (!pending_scrq(adapter, adapter->rx_scrq[scrq_num]))
 			break;
+		/* ensure that we do not prematurely exit the polling loop */
+		dma_rmb();
 		next = ibmvnic_next_scrq(adapter, adapter->rx_scrq[scrq_num]);
 		rx_buff =
 		    (struct ibmvnic_rx_buff *)be64_to_cpu(next->
@@ -3087,6 +3089,8 @@ static int ibmvnic_complete_tx(struct ibmvnic_adapter *adapter,
 		int num_entries = 0;
 
 		next = ibmvnic_next_scrq(adapter, scrq);
+		/* ensure that we are reading the correct queue entry */
+		dma_rmb();
 		for (i = 0; i < next->tx_comp.num_comps; i++) {
 			if (next->tx_comp.rcs[i]) {
 				dev_err(dev, "tx error %x\n",
-- 
2.26.2