On Sat, Jun 08, 2024 at 12:45:57PM +0800, Xiaolei Wang wrote:
> The current cbs parameter depends on speed after uplinking,
> which is not needed and will report a configuration error
> if the port is not initially connected. The UAPI exposed by
> tc-cbs requires userspace to recalculate the send slope anyway,
> because the formula depends on port_transmit_rate (see man tc-cbs),
> which is not an invariant from tc's perspective. Therefore, we
> use offload->sendslope and offload->idleslope to derive the
> original port_transmit_rate from the CBS formula.
>
> Fixes: 1f705bc61aee ("net: stmmac: Add support for CBS QDISC")
> Signed-off-by: Xiaolei Wang <[email protected]>
> Reviewed-by: Wojciech Drewek <[email protected]>
> ---
>
> Change log:
>
> v1:
> https://patchwork.kernel.org/project/linux-arm-kernel/patch/[email protected]/
> v2:
> Update CBS parameters when speed changes after linking up
> https://patchwork.kernel.org/project/linux-arm-kernel/patch/[email protected]/
> v3:
> replace priv->speed with the portTransmitRate from the tc-cbs parameters suggested by Vladimir Oltean
> link: https://patchwork.kernel.org/project/linux-arm-kernel/patch/[email protected]/
> v4:
> Delete speed_div variable, delete redundant port_transmit_rate_kbps = qopt->idleslope - qopt->sendslope; and update commit log
>
> .../net/ethernet/stmicro/stmmac/stmmac_tc.c | 20 +++++++------------
> 1 file changed, 7 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> index 222540b55480..87af129a6a1d 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> @@ -344,10 +344,11 @@ static int tc_setup_cbs(struct stmmac_priv *priv,
> {
> u32 tx_queues_count = priv->plat->tx_queues_to_use;
> u32 queue = qopt->queue;
> - u32 ptr, speed_div;
> + u32 ptr;
> u32 mode_to_use;
> u64 value;
> int ret;
> + s64 port_transmit_rate_kbps;
>
> /* Queue 0 is not AVB capable */
> if (queue <= 0 || queue >= tx_queues_count)
> @@ -355,27 +356,20 @@ static int tc_setup_cbs(struct stmmac_priv *priv,
> if (!priv->dma_cap.av)
> return -EOPNOTSUPP;
>
> + port_transmit_rate_kbps = qopt->idleslope - qopt->sendslope;
> +
> /* Port Transmit Rate and Speed Divider */
> - switch (priv->speed) {
> + switch (div_s64(port_transmit_rate_kbps, 1000)) {
> case SPEED_10000:
> - ptr = 32;
> - speed_div = 10000000;
> - break;
> case SPEED_5000:
> ptr = 32;
> - speed_div = 5000000;
> break;
> case SPEED_2500:
> - ptr = 8;
> - speed_div = 2500000;
> - break;
> case SPEED_1000:
> ptr = 8;
> - speed_div = 1000000;
> break;
> case SPEED_100:
> ptr = 4;
> - speed_div = 100000;
> break;
> default:
> return -EOPNOTSUPP;
I have one more request.
It is very discouraging for a user to give invalid parameters and
receive -EOPNOTSUPP, because this is indicative of other "usual
suspects": "did I enable CONFIG_NET_SCH_CBS?"
It is unfortunate that struct tc_cbs_qopt_offload does not carry a
netlink extack, but I'm also not requesting you to add one here.
Instead, please at least change the return code to something like
-EINVAL, and print something to the console along the lines of:
"Invalid portTransmitRate %lld (idleSlope - sendSlope)\n".