Add dma_rmb() barrier after req_id completion check in
ena_com_phc_get_timestamp(). On weakly-ordered architectures,
payload fields may be read before req_id is observed as updated.
Fixes: e0ea34158ee8 ("net: ena: Add PHC support in the ENA driver")
Closes: https://sashiko.dev/#/patchset/20260430032507.11586-1-akiyano%40amazon.com
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
---
drivers/net/ethernet/amazon/ena/ena_com.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c
index 8c86789d867a..297fb36ab8c1 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_com.c
@@ -1880,6 +1880,11 @@ int ena_com_phc_get_timestamp(struct ena_com_dev *ena_dev, u64 *timestamp)
continue;
}
+ /* Ensure PHC payload (timestamp, error_flags) is read
+ * after req_id update is observed
+ */
+ dma_rmb();
+
/* req_id was updated by the device which indicates that
* PHC timestamp and error_flags are updated too,
* checking errors before retrieving timestamp
--
2.47.3