The core locks ctx->indir_size when an RSS context is created. Some NICs (e.g. bnxt) change their indirection table size based on the channel count, because the hardware table is a shared resource. This forces drivers to reject channel changes when RSS contexts exist.
Add helpers to resize indirection tables: ethtool_rxfh_indir_can_resize() checks whether a table can be resized without modifying it. ethtool_rxfh_indir_resize() resizes a raw u32 table in place. Folding (shrink) requires the table to be periodic at the new size; non-periodic tables are rejected. Unfolding (grow) replicates the existing pattern. Sizes must be multiples of each other. ethtool_rxfh_contexts_resize_all() resizes all non-default RSS contexts. Validates every context before modifying any, so either all succeed or none are changed. Sends ETHTOOL_MSG_RSS_NTF per resized context after releasing rss_lock. No reallocation is needed because ethtool_rxfh_ctx_alloc() reserves space for rxfh_indir_space entries, and key_off is based on that maximum. Signed-off-by: Björn Töpel <[email protected]> --- include/linux/ethtool.h | 3 + net/ethtool/common.c | 126 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 129 insertions(+) diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h index 798abec67a1b..add7d16ca398 100644 --- a/include/linux/ethtool.h +++ b/include/linux/ethtool.h @@ -214,6 +214,9 @@ static inline u8 *ethtool_rxfh_context_key(struct ethtool_rxfh_context *ctx) } void ethtool_rxfh_context_lost(struct net_device *dev, u32 context_id); +int ethtool_rxfh_indir_can_resize(const u32 *tbl, u32 old_size, u32 new_size); +int ethtool_rxfh_indir_resize(u32 *tbl, u32 old_size, u32 new_size); +int ethtool_rxfh_contexts_resize_all(struct net_device *dev, u32 new_indir_size); struct link_mode_info { int speed; diff --git a/net/ethtool/common.c b/net/ethtool/common.c index e252cf20c22f..8df84ff9efa4 100644 --- a/net/ethtool/common.c +++ b/net/ethtool/common.c @@ -1204,6 +1204,132 @@ void ethtool_rxfh_context_lost(struct net_device *dev, u32 context_id) } EXPORT_SYMBOL(ethtool_rxfh_context_lost); +static bool ethtool_rxfh_indir_is_periodic(const u32 *tbl, u32 old_size, u32 new_size) +{ + u32 i; + + for (i = new_size; i < old_size; i++) + if (tbl[i] != tbl[i % new_size]) + return false; + return true; +} + +/** + * ethtool_rxfh_indir_can_resize - Check if an indirection table can be resized + * @tbl: indirection table + * @old_size: current number of entries in the table + * @new_size: desired number of entries + * + * Validate that @tbl can be resized from @old_size to @new_size without + * data loss. Read-only; does not modify the table. + * + * Return: 0 if resize is possible, -%EINVAL otherwise. + */ +int ethtool_rxfh_indir_can_resize(const u32 *tbl, u32 old_size, u32 new_size) +{ + if (old_size == 0 || new_size == 0) + return -EINVAL; + if (new_size == old_size) + return 0; + + if (new_size < old_size) { + if (old_size % new_size != 0) + return -EINVAL; + if (!ethtool_rxfh_indir_is_periodic(tbl, old_size, new_size)) + return -EINVAL; + return 0; + } + + if (new_size % old_size != 0) + return -EINVAL; + return 0; +} +EXPORT_SYMBOL(ethtool_rxfh_indir_can_resize); + +/* Resize without validation; caller must have called can_resize first */ +static void __ethtool_rxfh_indir_resize(u32 *tbl, u32 old_size, u32 new_size) +{ + u32 i; + + /* Unfold (grow): replicate existing pattern; fold is a no-op on the data */ + for (i = old_size; i < new_size; i++) + tbl[i] = tbl[i % old_size]; +} + +/** + * ethtool_rxfh_indir_resize - Fold or unfold an indirection table + * @tbl: indirection table (must have room for max(old_size, new_size) entries) + * @old_size: current number of entries in the table + * @new_size: desired number of entries + * + * Resize an RSS indirection table in place. When folding (shrinking), + * the table must be periodic with period @new_size; otherwise the + * operation is rejected. When unfolding (growing), the existing + * pattern is replicated. Both directions require the sizes to be + * multiples of each other. + * + * Return: 0 on success, -%EINVAL on failure (no mutation on failure). + */ +int ethtool_rxfh_indir_resize(u32 *tbl, u32 old_size, u32 new_size) +{ + int ret; + + ret = ethtool_rxfh_indir_can_resize(tbl, old_size, new_size); + if (ret) + return ret; + + __ethtool_rxfh_indir_resize(tbl, old_size, new_size); + return 0; +} +EXPORT_SYMBOL(ethtool_rxfh_indir_resize); + +/** + * ethtool_rxfh_contexts_resize_all - Resize all RSS context indirection tables + * @dev: network device + * @new_indir_size: new indirection table size + * + * Resize the indirection table of every non-default RSS context to + * @new_indir_size. Intended to be called from drivers when the + * device's indirection table size changes (e.g. on channel count + * change). An %ETHTOOL_MSG_RSS_NTF is sent for each resized context. + * + * All contexts are validated before any are modified, so either all + * contexts are resized or none are. + * + * Return: 0 on success, negative errno on failure. + */ +int ethtool_rxfh_contexts_resize_all(struct net_device *dev, u32 new_indir_size) +{ + struct ethtool_rxfh_context *ctx; + unsigned long context; + int ret; + + if (dev->ethtool_ops->rxfh_indir_space == 0 || + new_indir_size > dev->ethtool_ops->rxfh_indir_space) + return -EINVAL; + + scoped_guard(mutex, &dev->ethtool->rss_lock) { + xa_for_each(&dev->ethtool->rss_ctx, context, ctx) { + ret = ethtool_rxfh_indir_can_resize(ethtool_rxfh_context_indir(ctx), + ctx->indir_size, new_indir_size); + if (ret) + return ret; + } + + xa_for_each(&dev->ethtool->rss_ctx, context, ctx) { + __ethtool_rxfh_indir_resize(ethtool_rxfh_context_indir(ctx), + ctx->indir_size, new_indir_size); + ctx->indir_size = new_indir_size; + } + } + + xa_for_each(&dev->ethtool->rss_ctx, context, ctx) + ethtool_rss_notify(dev, ETHTOOL_MSG_RSS_NTF, context); + + return 0; +} +EXPORT_SYMBOL(ethtool_rxfh_contexts_resize_all); + enum ethtool_link_medium ethtool_str_to_medium(const char *str) { int i; -- 2.53.0
