[PATCH net v2] ethtool: Embed FEC hist ranges as buffer in struct
From: Eric Joyner <hidden>
Date: 2026-07-23 04:14:12
Subsystem:
mellanox ethernet driver (mlx5e), mellanox mlx5 core vpi driver, networking drivers, networking [ethtool], networking [general], the rest · Maintainers:
Saeed Mahameed, Tariq Toukan, Mark Bloch, Leon Romanovsky, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
When a driver's .get_fec_stats() handler is called and the driver
supports FEC histogram stats, the driver supplies the histogram bin
ranges via a pointer. This pointer is assigned while under the netdev
ops lock in fec_prepare_data(), but the actual data is only read after
the lock is released; so this allows the driver to change the ranges
(e.g. from another .get_fec_stats() call) while the current call chain
is reading them in fec_fill_reply().
Fix this by adding an ethtool core-owned buffer, ranges_buf, to struct
ethtool_fec_hist. Drivers whose ranges are built dynamically (currently
just mlx5) fill ranges_buf and then point the existing ranges pointer at
it, giving ethtool a consistent copy that stays valid after the netdev
ops lock is dropped and later in fec_fill_reply(). Drivers whose ranges
are compile-time constants (bnxt, netdevsim) are unaffected by the
potential race and keep setting the existing ranges pointer to their
constant array, without making copies.
Fixes: cc2f08129925 ("ethtool: add FEC bins histogram report")
Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Eric Joyner <redacted>
---
v2: Take Vadim Fedorenko's suggestion
(https://lore.kernel.org/netdev/f136bfb9-1756-4668-acc3-68962cdc6069@linux.dev/ (local))
and keep the ranges pointer for drivers that use constant ranges arrays;
only use the new memory for dynamically constructed ranges.
This makes this patch mostly an mlx5 change.
drivers/net/ethernet/mellanox/mlx5/core/en.h | 1 -
.../net/ethernet/mellanox/mlx5/core/en_main.c | 7 -------
.../ethernet/mellanox/mlx5/core/en_stats.c | 19 +++++++++----------
include/linux/ethtool.h | 1 +
4 files changed, 10 insertions(+), 18 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index d507289096c2..6867a5aed42c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h@@ -984,7 +984,6 @@ struct mlx5e_priv { struct mlx5e_mqprio_rl *mqprio_rl; struct dentry *dfs_root; struct mlx5_devcom_comp_dev *devcom; - struct ethtool_fec_hist_range *fec_ranges; }; static inline u16 mlx5e_stats_nch_read(const struct mlx5e_priv *priv)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index c1acb9012d3f..7d47a1da8b6b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c@@ -6415,14 +6415,8 @@ int mlx5e_priv_init(struct mlx5e_priv *priv, if (!priv->channel_stats) goto err_free_tx_rates; - priv->fec_ranges = kzalloc_objs(*priv->fec_ranges, ETHTOOL_FEC_HIST_MAX); - if (!priv->fec_ranges) - goto err_free_channel_stats; - return 0; -err_free_channel_stats: - kfree(priv->channel_stats); err_free_tx_rates: kfree(priv->tx_rates); err_free_txq2sq_stats:
@@ -6447,7 +6441,6 @@ void mlx5e_priv_cleanup(struct mlx5e_priv *priv) if (!priv->mdev) return; - kfree(priv->fec_ranges); for (i = 0; i < priv->stats_nch; i++) kvfree(priv->channel_stats[i]); kfree(priv->channel_stats);
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
index de38b60806c2..e7e6db7f6bf1 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c@@ -1550,7 +1550,7 @@ static bool fec_rs_validate_hist_type(int mode, int hist_type) static u8 fec_rs_histogram_fill_ranges(struct mlx5e_priv *priv, int mode, - const struct ethtool_fec_hist_range **ranges) + struct ethtool_fec_hist_range *ranges) { struct mlx5_core_dev *mdev = priv->mdev; u32 out[MLX5_ST_SZ_DW(pphcr_reg)] = {0};
@@ -1558,8 +1558,6 @@ fec_rs_histogram_fill_ranges(struct mlx5e_priv *priv, int mode, int sz = MLX5_ST_SZ_BYTES(pphcr_reg); u8 hist_type, num_of_bins; - memset(priv->fec_ranges, 0, - ETHTOOL_FEC_HIST_MAX * sizeof(*priv->fec_ranges)); MLX5_SET(pphcr_reg, in, local_port, 1); if (mlx5_core_access_reg(mdev, in, sz, out, sz, MLX5_REG_PPHCR, 0, 0)) return 0;
@@ -1575,12 +1573,11 @@ fec_rs_histogram_fill_ranges(struct mlx5e_priv *priv, int mode, for (int i = 0; i < num_of_bins; i++) { void *bin_range = MLX5_ADDR_OF(pphcr_reg, out, bin_range[i]); - priv->fec_ranges[i].high = MLX5_GET(bin_range_layout, bin_range, - high_val); - priv->fec_ranges[i].low = MLX5_GET(bin_range_layout, bin_range, - low_val); + ranges[i].high = MLX5_GET(bin_range_layout, bin_range, + high_val); + ranges[i].low = MLX5_GET(bin_range_layout, bin_range, + low_val); } - *ranges = priv->fec_ranges; return num_of_bins; }
@@ -1622,10 +1619,12 @@ static void fec_set_histograms_stats(struct mlx5e_priv *priv, int mode, case MLX5E_FEC_LLRS_272_257_1: case MLX5E_FEC_RS_544_514_INTERLEAVED_QUAD: num_of_bins = - fec_rs_histogram_fill_ranges(priv, mode, &hist->ranges); - if (num_of_bins) + fec_rs_histogram_fill_ranges(priv, mode, hist->ranges_buf); + if (num_of_bins) { + hist->ranges = hist->ranges_buf; return fec_rs_histogram_fill_stats(priv, num_of_bins, hist); + } break; default: return;
diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 5d491a98265e..12683b5d125e 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h@@ -562,6 +562,7 @@ struct ethtool_fec_hist { u64 per_lane[ETHTOOL_MAX_LANES]; } values[ETHTOOL_FEC_HIST_MAX]; const struct ethtool_fec_hist_range *ranges; + struct ethtool_fec_hist_range ranges_buf[ETHTOOL_FEC_HIST_MAX]; }; /** * struct ethtool_fec_stats - statistics for IEEE 802.3 FEC
base-commit: fca68249b6f5e84859b200b54cb5e0aef98f2b3a -- 2.17.1