[PATCH net 10/18] net/ena: use READ_ONCE to access completion descriptors

[Netanel Belgazal]

Completion descriptors are accessed from the driver and from the device.
To avoid reading the old value, use READ_ONCE macro.

Signed-off-by: Netanel Belgazal <neta...@annapurnalabs.com>
---
 drivers/net/ethernet/amazon/ena/ena_com.h     | 1 +
 drivers/net/ethernet/amazon/ena/ena_eth_com.c | 8 ++++----
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_com.h 
b/drivers/net/ethernet/amazon/ena/ena_com.h
index 6883ee5..f8cdce0 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.h
+++ b/drivers/net/ethernet/amazon/ena/ena_com.h
@@ -33,6 +33,7 @@
 #ifndef ENA_COM
 #define ENA_COM
 
+#include <linux/compiler.h>
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
 #include <linux/gfp.h>
diff --git a/drivers/net/ethernet/amazon/ena/ena_eth_com.c 
b/drivers/net/ethernet/amazon/ena/ena_eth_com.c
index 539c536..f999305 100644
--- a/drivers/net/ethernet/amazon/ena/ena_eth_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_eth_com.c
@@ -45,7 +45,7 @@ static inline struct ena_eth_io_rx_cdesc_base 
*ena_com_get_next_rx_cdesc(
        cdesc = (struct ena_eth_io_rx_cdesc_base *)(io_cq->cdesc_addr.virt_addr
                        + (head_masked * io_cq->cdesc_entry_size_in_bytes));
 
-       desc_phase = (cdesc->status & ENA_ETH_IO_RX_CDESC_BASE_PHASE_MASK) >>
+       desc_phase = (READ_ONCE(cdesc->status) & 
ENA_ETH_IO_RX_CDESC_BASE_PHASE_MASK) >>
                        ENA_ETH_IO_RX_CDESC_BASE_PHASE_SHIFT;
 
        if (desc_phase != expected_phase)
@@ -141,7 +141,7 @@ static inline u16 ena_com_cdesc_rx_pkt_get(struct 
ena_com_io_cq *io_cq,
 
                ena_com_cq_inc_head(io_cq);
                count++;
-               last = (cdesc->status & ENA_ETH_IO_RX_CDESC_BASE_LAST_MASK) >>
+               last = (READ_ONCE(cdesc->status) & 
ENA_ETH_IO_RX_CDESC_BASE_LAST_MASK) >>
                        ENA_ETH_IO_RX_CDESC_BASE_LAST_SHIFT;
        } while (!last);
 
@@ -489,13 +489,13 @@ int ena_com_tx_comp_req_id_get(struct ena_com_io_cq 
*io_cq, u16 *req_id)
         * expected, it mean that the device still didn't update
         * this completion.
         */
-       cdesc_phase = cdesc->flags & ENA_ETH_IO_TX_CDESC_PHASE_MASK;
+       cdesc_phase = READ_ONCE(cdesc->flags) & ENA_ETH_IO_TX_CDESC_PHASE_MASK;
        if (cdesc_phase != expected_phase)
                return -EAGAIN;
 
        ena_com_cq_inc_head(io_cq);
 
-       *req_id = cdesc->req_id;
+       *req_id = READ_ONCE(cdesc->req_id);
 
        return 0;
 }
-- 
1.9.1