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 033f17cb96be022a966886a8c1f241cd32c59b78..7e60139f8ac574424e6be43241e14da88dc81912 100644 (file)
--- a/drivers/net/ethernet/google/gve/gve_ethtool.c
+++ b/drivers/net/ethernet/google/gve/gve_ethtool.c
@@ -327,7 +327,9 @@ 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 =