[PATCH net 1/2] sfc: fix wrong tx channel offset with efx_separate_tx_channels

["Íñigo Huguet" <ihuguet@redhat.com>]

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: 3990a8fffbda ("sfc: allocate channels for XDP tx queues")
Reported-by: Tianhao Zhao <tizhao@redhat.com>
Signed-off-by: Íñigo Huguet <ihuguet@redhat.com>
---
 drivers/net/ethernet/sfc/efx_channels.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/sfc/efx_channels.c b/drivers/net/ethernet/sfc/efx_channels.c
index 40df910aa140..da2db6791907 100644
--- a/drivers/net/ethernet/sfc/efx_channels.c
+++ b/drivers/net/ethernet/sfc/efx_channels.c
@@ -241,14 +241,9 @@ static int efx_allocate_msix_channels(struct efx_nic *efx,
 	n_channels -= efx->n_xdp_channels;
 
 	if (efx_separate_tx_channels) {
-		efx->n_tx_channels =
-			min(max(n_channels / 2, 1U),
-			    efx->max_tx_channels);
-		efx->tx_channel_offset =
-			n_channels - efx->n_tx_channels;
-		efx->n_rx_channels =
-			max(n_channels -
-			    efx->n_tx_channels, 1U);
+		efx->n_tx_channels = min(max(n_channels / 2, 1U), efx->max_tx_channels);
+		efx->tx_channel_offset = n_channels - efx->n_tx_channels;
+		efx->n_rx_channels = max(n_channels - efx->n_tx_channels, 1U);
 	} else {
 		efx->n_tx_channels = min(n_channels, efx->max_tx_channels);
 		efx->tx_channel_offset = 0;
@@ -324,6 +319,7 @@ 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);
@@ -344,6 +340,7 @@ 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;
@@ -979,10 +976,6 @@ int efx_set_channels(struct efx_nic *efx)
 	struct efx_channel *channel;
 	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);
 
-- 
2.34.1