sfc: fix wrong tx channel offset with efx_separate_tx_channels

stable inclusion
from stable-v5.10.122
commit bf2af9b24313553f3f0b30443220ab0ac8595d2d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5W6OE

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bf2af9b24313553f3f0b30443220ab0ac8595d2d

--------------------------------

[ Upstream commit c308dfd1 ]

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.

Fixes: 3990a8ff ("sfc: allocate channels for XDP tx queues")
Reported-by: NTianhao Zhao <tizhao@redhat.com>
Signed-off-by: NÍñigo Huguet <ihuguet@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

drivers/net/ethernet/sfc/efx_channels.c

@@ -287,6 +287,7 @@ int efx_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);
@@ -307,6 +308,7 @@ int efx_probe_interrupts(struct efx_nic *efx)
 		efx->n_channels = 1 + (efx_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;
@@ -858,10 +860,6 @@ int efx_set_channels(struct efx_nic *efx)
 	int xdp_queue_number;
 	int rc;
 
-	efx->tx_channel_offset =
-		efx_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);