Re: [PATCH net-next v4 08/13] net: wwan: t7xx: Add data path interface

On Tue, 15 Feb 2022, Martinez, Ricardo wrote:

On 2/8/2022 12:19 AM, Ilpo Järvinen wrote:

quoted

On Thu, 13 Jan 2022, Ricardo Martinez wrote:

quoted

+/* SKB control buffer indexed values */
+#define TX_CB_NETIF_IDX		0
+#define TX_CB_QTYPE		1
+#define TX_CB_DRB_CNT		2

The normal way of storing a struct to skb->cb area is:

struct t7xx_skb_cb {
	u8	netif_idx;
	u8	qtype;
	u8	drb_cnt;
};

#define T7XX_SKB_CB(__skb)	((struct t7xx_skb_cb *)&((__skb)->cb[0]))

However, there's only a single txqt/qtype (TXQ_TYPE_DEFAULT) in the
patchset? And it seems to me that drb_cnt is a value that could be always
derived using t7xx_get_drb_cnt_per_skb() from the skb rather than
stored?

The next iteration will contain t7xx_tx_skb_cb and t7xx_rx_skb_cb structures.

Ah, I didn't even notice the other one. Why differentiate them? There's 
enough space in cb area and netif_idx is in both anyway. (union inside 
struct could be used if short on space and tx/rx differ but it is not 
needed here now.)

Also, q_number is going to be used instead of qtype.

Only one queue is used but I think we can keep this code generic as it is
straight forward (not like the drb_lack case), any thoughts?

I don't mind if you find it useful.


-- 
 i.