gve: handle overflow when reporting TX consumed descriptors

commit 15970e1b23f5c25db88c613fddf9131de086f28e upstream.

When the tx tail is less than the head (in cases of wraparound), the TX
consumed descriptor statistic in DQ will be reported as
UINT32_MAX - head + tail, which is incorrect. Mask the difference of
head and tail according to the ring size when reporting the statistic.

Cc: stable@vger.kernel.org
Fixes: 2c9198356d56 ("gve: Add consumed counts to ethtool stats")
Signed-off-by: Joshua Washington <joshwash@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250402001037.2717315-1-hramamurthy@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/google/gve/gve_ethtool.c b/drivers/net/ethernet/google/gve/gve_ethtool.c
index 233e5946905e7dfa4bb7f0bf2955cd316b352b21..22317acf16ba4df744f45aa4874360e23e774d63 100644 (file)
--- a/drivers/net/ethernet/google/gve/gve_ethtool.c
+++ b/drivers/net/ethernet/google/gve/gve_ethtool.c
@@ -356,7 +356,9 @@ gve_get_ethtool_stats(struct net_device *netdev,
                                 */
                                data[i++] = 0;
                                data[i++] = 0;
-                               data[i++] = tx->dqo_tx.tail - tx->dqo_tx.head;
+                               data[i++] =
+                                       (tx->dqo_tx.tail - tx->dqo_tx.head) &
+                                       tx->mask;
                        }
                        do {
                                start =