net: bcmasp: Handle RX buffer allocation failure

The buffer_pg variable needs to hold an order-5 allocation (32 x
PAGE_SIZE) which, under memory pressure may fail to be allocated. Deal
with that error condition properly to avoid doing a NULL pointer
de-reference in the subsequent call to dma_map_page().

In addition, the err_reclaim_tx error label in bcmasp_netif_init() needs
to ensure that the TX NAPI object is properly deleted, otherwise
unregister_netdev() will spin forever attempting to test and clear
the NAPI_STATE_HASHED bit.

Fixes: 490cb412007d ("net: bcmasp: Add support for ASP2.0 Ethernet controller")
Signed-off-by: Florian Fainelli <[e-mail]>
Reviewed-by: Justin Chen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

drivers/net/ethernet/broadcom/asp2/bcmasp_intf.c

···
 
 	intf->rx_buf_order = get_order(RING_BUFFER_SIZE);
 	buffer_pg = alloc_pages(GFP_KERNEL, intf->rx_buf_order);
+	if (!buffer_pg)
+		return -ENOMEM;
 
 	dma = dma_map_page(kdev, buffer_pg, 0, RING_BUFFER_SIZE,
 			   DMA_FROM_DEVICE);
···
 	return 0;
 
 err_reclaim_tx:
+	netif_napi_del(&intf->tx_napi);
 	bcmasp_reclaim_free_all_tx(intf);
 err_phy_disconnect:
 	if (phydev)