net: airoha: Add size check for TX NAPIs in airoha_qdma_cleanup()

If airoha_qdma_init routine fails before airoha_qdma_tx_irq_init() runs
successfully for all TX NAPIs, airoha_qdma_cleanup() will
unconditionally runs netif_napi_del() on TX NAPIs, triggering a NULL
pointer dereference. Fix the issue relying on q_tx_irq size value to
check if the TX NAPIs is properly initialized in airoha_qdma_cleanup().
Moreover, run netif_napi_add_tx() just if irq_q queue is properly
allocated.

Fixes: 23020f0 ("net: airoha: Introduce ethernet support for EN7581 SoC")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260420-airoha_qdma_init_rx_queue-fix-v2-2-d99347e5c18d@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: LorenzoBianconi

drivers/net/ethernet/airoha/airoha_eth.c

@@ -1020,8 +1020,6 @@ static int airoha_qdma_tx_irq_init(struct airoha_tx_irq_queue *irq_q,
 	struct airoha_eth *eth = qdma->eth;
 	dma_addr_t dma_addr;
 
-	netif_napi_add_tx(eth->napi_dev, &irq_q->napi,
-			  airoha_qdma_tx_napi_poll);
 	irq_q->q = dmam_alloc_coherent(eth->dev, size * sizeof(u32),
 				       &dma_addr, GFP_KERNEL);
 	if (!irq_q->q)
@@ -1031,6 +1029,9 @@ static int airoha_qdma_tx_irq_init(struct airoha_tx_irq_queue *irq_q,
 	irq_q->size = size;
 	irq_q->qdma = qdma;
 
+	netif_napi_add_tx(eth->napi_dev, &irq_q->napi,
+			  airoha_qdma_tx_napi_poll);
+
 	airoha_qdma_wr(qdma, REG_TX_IRQ_BASE(id), dma_addr);
 	airoha_qdma_rmw(qdma, REG_TX_IRQ_CFG(id), TX_IRQ_DEPTH_MASK,
 			FIELD_PREP(TX_IRQ_DEPTH_MASK, size));
@@ -1450,8 +1451,12 @@ static void airoha_qdma_cleanup(struct airoha_qdma *qdma)
 		}
 	}
 
-	for (i = 0; i < ARRAY_SIZE(qdma->q_tx_irq); i++)
+	for (i = 0; i < ARRAY_SIZE(qdma->q_tx_irq); i++) {
+		if (!qdma->q_tx_irq[i].size)
+			continue;
+
 		netif_napi_del(&qdma->q_tx_irq[i].napi);
+	}
 
 	for (i = 0; i < ARRAY_SIZE(qdma->q_tx); i++) {
 		if (!qdma->q_tx[i].ndesc)