[PATCH net-next v3 6/8] ethtool: add helper to prevent invalid statistics exposure to userspace
From: Oleksij Rempel <o.rempel@pengutronix.de>
Date: 2024-12-20 13:09:05
Also in:
linux-doc, lkml
Subsystem:
networking [ethtool], networking [general], the rest · Maintainers:
Andrew Lunn, Jakub Kicinski, "David S. Miller", Eric Dumazet, Paolo Abeni, Linus Torvalds
Introduce a new helper function, `ethtool_stat_add`, to update 64-bit statistics with proper handling of the reserved value `ETHTOOL_STAT_NOT_SET`. This ensures that statistics remain valid and are always reported to userspace, even if the driver accidentally sets `ETHTOOL_STAT_NOT_SET` during an update. Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> Reviewed-by: Mateusz Polchlopek <redacted> --- changes v2: - add "Reviewed-by: Mateusz Polchlopek [off-list ref]" --- include/linux/ethtool.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 4bf70cfec826..c0d3e3f62faf 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h@@ -371,6 +371,22 @@ static inline void ethtool_stats_init(u64 *stats, unsigned int n) stats[n] = ETHTOOL_STAT_NOT_SET; } +/** + * ethtool_stat_add - Add a value to a u64 statistic with wraparound handling + * @stat: Pointer to the statistic to update + * @value: Value to add to the statistic + * + * Adds the specified value to a u64 statistic. If the result of the addition + * equals the reserved value (`ETHTOOL_STAT_NOT_SET`), it increments the result + * by 1 to avoid the reserved value. + */ +static inline void ethtool_stat_add(u64 *stat, u64 value) +{ + *stat += value; + if (*stat == ETHTOOL_STAT_NOT_SET) + (*stat)++; +} + /* Basic IEEE 802.3 MAC statistics (30.3.1.1.*), not otherwise exposed * via a more targeted API. */
--
2.39.5