Re: [PATCH net v2 2/2] sfc/siena: fix wrong tx channel offset with efx_separate_tx_channels

[Martin Habets <habetsm.xilinx@gmail.com>]

On Wed, Jun 01, 2022 at 08:36:03AM +0200, Íñigo Huguet wrote:
> tx_channel_offset is calculated in efx_allocate_msix_channels, but it is
> also calculated again in efx_set_channels because it was originally done
> there, and when efx_allocate_msix_channels was introduced it was
> forgotten to be removed from efx_set_channels.
> 
> Moreover, the old calculation is wrong when using
> efx_separate_tx_channels because now we can have XDP channels after the
> TX channels, so n_channels - n_tx_channels doesn't point to the first TX
> channel.
> 
> Remove the old calculation from efx_set_channels, and add the
> initialization of this variable if MSI or legacy interrupts are used,
> next to the initialization of the rest of the related variables, where
> it was missing.
> 
> This has been already done for sfc, do it also for sfc_siena.
> 
> Fixes: 3990a8fffbda ("sfc: allocate channels for XDP tx queues")
> Reported-by: Tianhao Zhao <tizhao@redhat.com>
> Signed-off-by: Íñigo Huguet <ihuguet@redhat.com>

Acked-by: Martin Habets <habetsm.xilinx@gmail.com>

> ---
>  drivers/net/ethernet/sfc/siena/efx_channels.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/sfc/siena/efx_channels.c b/drivers/net/ethernet/sfc/siena/efx_channels.c
> index 2465cf4d505c..017212a40df3 100644
> --- a/drivers/net/ethernet/sfc/siena/efx_channels.c
> +++ b/drivers/net/ethernet/sfc/siena/efx_channels.c
> @@ -299,6 +299,7 @@ int efx_siena_probe_interrupts(struct efx_nic *efx)
>  		efx->n_channels = 1;
>  		efx->n_rx_channels = 1;
>  		efx->n_tx_channels = 1;
> +		efx->tx_channel_offset = 0;
>  		efx->n_xdp_channels = 0;
>  		efx->xdp_channel_offset = efx->n_channels;
>  		rc = pci_enable_msi(efx->pci_dev);
> @@ -319,6 +320,7 @@ int efx_siena_probe_interrupts(struct efx_nic *efx)
>  		efx->n_channels = 1 + (efx_siena_separate_tx_channels ? 1 : 0);
>  		efx->n_rx_channels = 1;
>  		efx->n_tx_channels = 1;
> +		efx->tx_channel_offset = 1;
>  		efx->n_xdp_channels = 0;
>  		efx->xdp_channel_offset = efx->n_channels;
>  		efx->legacy_irq = efx->pci_dev->irq;
> @@ -958,10 +960,6 @@ int efx_siena_set_channels(struct efx_nic *efx)
>  	struct efx_channel *channel;
>  	int rc;
>  
> -	efx->tx_channel_offset =
> -		efx_siena_separate_tx_channels ?
> -		efx->n_channels - efx->n_tx_channels : 0;
> -
>  	if (efx->xdp_tx_queue_count) {
>  		EFX_WARN_ON_PARANOID(efx->xdp_tx_queues);
>  
> -- 
> 2.34.1