net: enetc: optimize the allocation of tx_bdr

There is a situation where num_tx_rings cannot be divided by bdr_int_num.
For example, num_tx_rings is 8 and bdr_int_num is 3. According to the
previous logic, this results in two tx_bdr corresponding memories not
being allocated, so when sending packets to tx ring 6 or 7, wild pointers
will be accessed. Of course, this issue doesn't exist on LS1028A, because
its num_tx_rings is 8, and bdr_int_num is either 1 or 2. However, there
is a risk for the upcoming i.MX95. Therefore, it is necessary to ensure
that each tx_bdr can be allocated to the corresponding memory.

Signed-off-by: Clark Wang <[email protected]>
Signed-off-by: Wei Fang <[email protected]>
Reviewed-by: Claudiu Manoil <[email protected]>
Reviewed-by: Frank Li <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: wangxiaoningnxp

drivers/net/ethernet/freescale/enetc/enetc.c

@@ -3084,10 +3084,10 @@ static void enetc_int_vector_destroy(struct enetc_ndev_priv *priv, int i)
 int enetc_alloc_msix(struct enetc_ndev_priv *priv)
 {
 	struct pci_dev *pdev = priv->si->pdev;
+	int v_tx_rings, v_remainder;
 	int num_stack_tx_queues;
 	int first_xdp_tx_ring;
 	int i, n, err, nvec;
-	int v_tx_rings;
 
 	nvec = ENETC_BDR_INT_BASE_IDX + priv->bdr_int_num;
 	/* allocate MSIX for both messaging and Rx/Tx interrupts */
@@ -3101,9 +3101,15 @@ int enetc_alloc_msix(struct enetc_ndev_priv *priv)
 
 	/* # of tx rings per int vector */
 	v_tx_rings = priv->num_tx_rings / priv->bdr_int_num;
+	v_remainder = priv->num_tx_rings % priv->bdr_int_num;
 
 	for (i = 0; i < priv->bdr_int_num; i++) {
-		err = enetc_int_vector_init(priv, i, v_tx_rings);
+		/* Distribute the remaining TX rings to the first v_remainder
+		 * interrupt vectors
+		 */
+		int num_tx_rings = i < v_remainder ? v_tx_rings + 1 : v_tx_rings;
+
+		err = enetc_int_vector_init(priv, i, num_tx_rings);
 		if (err)
 			goto fail;
 	}