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Subject[PATCH V2 net 11/20] net/ena: use READ_ONCE to access completion descriptors
Date
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 <netanel@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;
}
--
2.7.4
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