diff mbox series

[net-next,v5,6/8] ethtool: add helper to prevent invalid statistics exposure to userspace

Message ID 20250106083301.1039850-7-o.rempel@pengutronix.de (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series Introduce unified and structured PHY | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 7 this patch: 7
netdev/build_tools success Errors and warnings before: 0 (+23) this patch: 0 (+23)
netdev/cc_maintainers success CCed 5 of 5 maintainers
netdev/build_clang success Errors and warnings before: 4078 this patch: 4078
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1663 this patch: 1663
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 22 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 3 this patch: 3
netdev/source_inline success Was 0 now: 0

Commit Message

Oleksij Rempel Jan. 6, 2025, 8:32 a.m. UTC 
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 <mateusz.polchlopek@intel.com>
---
changes v2:
- add "Reviewed-by: Mateusz Polchlopek <mateusz.polchlopek@intel.com>"
---
 include/linux/ethtool.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Comments

Jakub Kicinski Jan. 8, 2025, 2:05 a.m. UTC | #1 
On Mon,  6 Jan 2025 09:32:59 +0100 Oleksij Rempel wrote:
> 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.

u64 can't wrap. If it could we should be using a wider type 
to count packets/bytes. I don't see the need for this, sorry 
for missing the discussion.
diff mbox series

Patch

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.
  */