Re: [PATCH net-next 3/5] net/mlx5e: resize non-default RSS indirection tables on channel change

[sashiko-bot@kernel.org]

> From: Yael Chemla <ychemla@nvidia.com>
> 
> When the channel count changes and the RQT size changes with it, a
> problem arise for non-default RSS contexts. The driver-side indirection
> table grows actual_table_size without filling the new entries; stale
> entries from a prior larger configuration may be re-exposed, causing
> mlx5e_calc_indir_rqns() to WARN on an out-of-range index.
> 
> Replace mlx5e_rss_params_indir_modify_actual_size() with
> mlx5e_rss_ctx_resize(), which fills new entries by replicating
> the existing pattern, matching what ethtool_rxfh_ctxs_resize() does
> for the same case. And restrict the loop to non-default contexts.
> 
> Call ethtool_rxfh_ctxs_can_resize() before acquiring state_lock to
> validate that all non-default contexts can be resized, and
> ethtool_rxfh_ctxs_resize() after releasing it to fold or unfold their
> indirection tables. Both functions acquire rss_lock internally and
> cannot be called under state_lock. RTNL, held by all set_channels
> callers, serialises context creation and deletion making the pre-lock
> check safe.
> 
> Guard both ethtool calls on mlx5e_rx_res_rss_cnt() > 1: skip the
> validation and resize when no non-default contexts exist. This
> naturally covers representors and IPoIB, which share
> mlx5e_ethtool_set_channels() but cannot have non-default RSS contexts.
> 
> Signed-off-by: Yael Chemla <ychemla@nvidia.com>
> Reviewed-by: Nimrod Oren <noren@nvidia.com>
> Signed-off-by: Tariq Toukan <tariqt@nvidia.com>

Sashiko has reviewed this patch and found no issues.

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