Re: [PATCH net-next v3 2/3] net: ti: icssg-prueth: introduce and use prueth_swdata struct for SWDATA

["Malladi, Meghana" <m-malladi@xxxxxx>]

On 2/27/2025 5:57 PM, Roger Quadros wrote:
> On 24/02/2025 13:01, Meghana Malladi wrote:
> > From: Roger Quadros <rogerq@xxxxxxxxxx>
> >
> > We have different cases for SWDATA (skb, page, cmd, etc)
> > so it is better to have a dedicated data structure for that.
> > We can embed the type field inside the struct and use it
> > to interpret the data in completion handlers.
> >
> > Increase SWDATA size to 48 so we have some room to add
> > more data if required.
> >
> > Signed-off-by: Roger Quadros <rogerq@xxxxxxxxxx>
> > Signed-off-by: MD Danish Anwar <danishanwar@xxxxxx>
> > Signed-off-by: Meghana Malladi <m-malladi@xxxxxx>
> > ---
> > Changes since v2 (v3-v2):
> > - Fix leaking tx descriptor in emac_tx_complete_packets()
> > - Free rx descriptor if swdata type is not page in emac_rx_packet()
> > - Revert back the size of PRUETH_NAV_SW_DATA_SIZE
> > - Use build time check for prueth_swdata size
> > - re-write prueth_swdata to have enum type as first member in the struct
> > and prueth_data union embedded in the struct
> >
> > All the above changes have been suggested by Roger Quadros <rogerq@xxxxxxxxxx>
> >
> >   drivers/net/ethernet/ti/icssg/icssg_common.c  | 52 +++++++++++++------
> >   drivers/net/ethernet/ti/icssg/icssg_prueth.c  |  3 ++
> >   drivers/net/ethernet/ti/icssg/icssg_prueth.h  | 16 ++++++
> >   .../net/ethernet/ti/icssg/icssg_prueth_sr1.c  |  4 +-
> >   4 files changed, 57 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/ti/icssg/icssg_common.c b/drivers/net/ethernet/ti/icssg/icssg_common.c
> > index acbb79ad8b0c..01eeabe83eff 100644
> > --- a/drivers/net/ethernet/ti/icssg/icssg_common.c
> > +++ b/drivers/net/ethernet/ti/icssg/icssg_common.c
> > @@ -136,12 +136,12 @@ int emac_tx_complete_packets(struct prueth_emac *emac, int chn,
> >   	struct net_device *ndev = emac->ndev;
> >   	struct cppi5_host_desc_t *desc_tx;
> >   	struct netdev_queue *netif_txq;
> > +	struct prueth_swdata *swdata;
> >   	struct prueth_tx_chn *tx_chn;
> >   	unsigned int total_bytes = 0;
> >   	struct sk_buff *skb;
> >   	dma_addr_t desc_dma;
> >   	int res, num_tx = 0;
> > -	void **swdata;
> >   
> >   	tx_chn = &emac->tx_chns[chn];
> >   
> > @@ -163,12 +163,19 @@ int emac_tx_complete_packets(struct prueth_emac *emac, int chn,
> >   		swdata = cppi5_hdesc_get_swdata(desc_tx);
> >   
> >   		/* was this command's TX complete? */
> > -		if (emac->is_sr1 && *(swdata) == emac->cmd_data) {
> > +		if (emac->is_sr1 && (void *)(swdata) == emac->cmd_data) {
> >   			prueth_xmit_free(tx_chn, desc_tx);
> >   			continue;
> >   		}
> >   
> > -		skb = *(swdata);
> > +		if (swdata->type != PRUETH_SWDATA_SKB) {
> > +			netdev_err(ndev, "tx_complete: invalid swdata type %d\n", swdata->type);
> > +			prueth_xmit_free(tx_chn, desc_tx);
> > +			budget++;
>
> I don't recollect why we need to increase budget here.

Probably because this packet hasn't been processed due to invalid swdata 
we are increasing the budget to compensate the loss -> but sounds 
counter intuitive to whole idea of using the budget. Will remove it.


> > +			continue;
> > +		}
> > +
> > +		skb = swdata->data.skb;
> >   		prueth_xmit_free(tx_chn, desc_tx);
>
> if we set swdata->type to PRUETH_SWDATA_CMD in emac_send_command_sr1() then we could
> reduce all above code including both ifs to
>
> 		swdata = cppi5_hdesc_get_swdata(desc_tx);
> 		prueth_xmit_free(tx_chn, desc_tx);
> 		if (swdata->type != PRUETH_SWDATA_SKB)
> 			continue;
>
> 		skb = swdata->data.skb;

Yes this is a nice change. This also addresses the concern Dan pointed 
out regarding SR1's emac->cmd_data check. I was also wondering the same 
to use PRUETH_SWDATA_CMD for addressing Dan's comment. Thanks.

> >   
> >   		ndev = skb->dev;
> > @@ -472,9 +479,9 @@ int prueth_dma_rx_push_mapped(struct prueth_emac *emac,
> >   {
> >   	struct net_device *ndev = emac->ndev;
> >   	struct cppi5_host_desc_t *desc_rx;
> > +	struct prueth_swdata *swdata;
> >   	dma_addr_t desc_dma;
> >   	dma_addr_t buf_dma;
> > -	void **swdata;
> >   
> >   	buf_dma = page_pool_get_dma_addr(page) + PRUETH_HEADROOM;
> >   	desc_rx = k3_cppi_desc_pool_alloc(rx_chn->desc_pool);
> > @@ -490,7 +497,8 @@ int prueth_dma_rx_push_mapped(struct prueth_emac *emac,
> >   	cppi5_hdesc_attach_buf(desc_rx, buf_dma, buf_len, buf_dma, buf_len);
> >   
> >   	swdata = cppi5_hdesc_get_swdata(desc_rx);
> > -	*swdata = page;
> > +	swdata->type = PRUETH_SWDATA_PAGE;
> > +	swdata->data.page = page;
> >   
> >   	return k3_udma_glue_push_rx_chn(rx_chn->rx_chn, PRUETH_RX_FLOW_DATA,
> >   					desc_rx, desc_dma);
> > @@ -539,11 +547,11 @@ static int emac_rx_packet(struct prueth_emac *emac, u32 flow_id)
> >   	u32 buf_dma_len, pkt_len, port_id = 0;
> >   	struct net_device *ndev = emac->ndev;
> >   	struct cppi5_host_desc_t *desc_rx;
> > +	struct prueth_swdata *swdata;
> >   	dma_addr_t desc_dma, buf_dma;
> >   	struct page *page, *new_page;
> >   	struct page_pool *pool;
> >   	struct sk_buff *skb;
> > -	void **swdata;
> >   	u32 *psdata;
> >   	void *pa;
> >   	int ret;
> > @@ -561,7 +569,13 @@ static int emac_rx_packet(struct prueth_emac *emac, u32 flow_id)
> >   
> >   	desc_rx = k3_cppi_desc_pool_dma2virt(rx_chn->desc_pool, desc_dma);
> >   	swdata = cppi5_hdesc_get_swdata(desc_rx);
> > -	page = *swdata;
> > +	if (swdata->type != PRUETH_SWDATA_PAGE) {
> > +		netdev_err(ndev, "rx_pkt: invalid swdata->type %d\n", swdata->type);
> > +		k3_cppi_desc_pool_free(rx_chn->desc_pool, desc_rx);
> > +		return 0;
> > +	}
> > +
> > +	page = swdata->data.page;
> >   	page_pool_dma_sync_for_cpu(pool, page, 0, PAGE_SIZE);
> >   	cppi5_hdesc_get_obuf(desc_rx, &buf_dma, &buf_dma_len);
> >   	k3_udma_glue_rx_cppi5_to_dma_addr(rx_chn->rx_chn, &buf_dma);
> > @@ -626,15 +640,18 @@ static void prueth_rx_cleanup(void *data, dma_addr_t desc_dma)
> >   {
> >   	struct prueth_rx_chn *rx_chn = data;
> >   	struct cppi5_host_desc_t *desc_rx;
> > +	struct prueth_swdata *swdata;
> >   	struct page_pool *pool;
> >   	struct page *page;
> > -	void **swdata;
> >   
> >   	pool = rx_chn->pg_pool;
> >   	desc_rx = k3_cppi_desc_pool_dma2virt(rx_chn->desc_pool, desc_dma);
> >   	swdata = cppi5_hdesc_get_swdata(desc_rx);
> > -	page = *swdata;
> > -	page_pool_recycle_direct(pool, page);
> > +	if (swdata->type == PRUETH_SWDATA_PAGE) {
> > +		page = swdata->data.page;
> > +		page_pool_recycle_direct(pool, page);
> > +	}
> > +
> >   	k3_cppi_desc_pool_free(rx_chn->desc_pool, desc_rx);
> >   }
> >   
> > @@ -671,13 +688,13 @@ enum netdev_tx icssg_ndo_start_xmit(struct sk_buff *skb, struct net_device *ndev
> >   	struct prueth_emac *emac = netdev_priv(ndev);
> >   	struct prueth *prueth = emac->prueth;
> >   	struct netdev_queue *netif_txq;
> > +	struct prueth_swdata *swdata;
> >   	struct prueth_tx_chn *tx_chn;
> >   	dma_addr_t desc_dma, buf_dma;
> >   	u32 pkt_len, dst_tag_id;
> >   	int i, ret = 0, q_idx;
> >   	bool in_tx_ts = 0;
> >   	int tx_ts_cookie;
> > -	void **swdata;
> >   	u32 *epib;
> >   
> >   	pkt_len = skb_headlen(skb);
> > @@ -739,7 +756,8 @@ enum netdev_tx icssg_ndo_start_xmit(struct sk_buff *skb, struct net_device *ndev
> >   	k3_udma_glue_tx_dma_to_cppi5_addr(tx_chn->tx_chn, &buf_dma);
> >   	cppi5_hdesc_attach_buf(first_desc, buf_dma, pkt_len, buf_dma, pkt_len);
> >   	swdata = cppi5_hdesc_get_swdata(first_desc);
> > -	*swdata = skb;
> > +	swdata->type = PRUETH_SWDATA_SKB;
> > +	swdata->data.skb = skb;
> >   
> >   	/* Handle the case where skb is fragmented in pages */
> >   	cur_desc = first_desc;
> > @@ -842,15 +860,17 @@ static void prueth_tx_cleanup(void *data, dma_addr_t desc_dma)
> >   {
> >   	struct prueth_tx_chn *tx_chn = data;
> >   	struct cppi5_host_desc_t *desc_tx;
> > +	struct prueth_swdata *swdata;
> >   	struct sk_buff *skb;
> > -	void **swdata;
> >   
> >   	desc_tx = k3_cppi_desc_pool_dma2virt(tx_chn->desc_pool, desc_dma);
> >   	swdata = cppi5_hdesc_get_swdata(desc_tx);
> > -	skb = *(swdata);
> > -	prueth_xmit_free(tx_chn, desc_tx);
> > +	if (swdata->type == PRUETH_SWDATA_SKB) {
> > +		skb = swdata->data.skb;
> > +		dev_kfree_skb_any(skb);
> > +	}
> >   
> > -	dev_kfree_skb_any(skb);
> > +	prueth_xmit_free(tx_chn, desc_tx);
> >   }
> >   
> >   irqreturn_t prueth_rx_irq(int irq, void *dev_id)
> > diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.c b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> > index 00ed97860547..3ff8c322f9d9 100644
> > --- a/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> > +++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> > @@ -1522,6 +1522,9 @@ static int prueth_probe(struct platform_device *pdev)
> >   
> >   	np = dev->of_node;
> >   
> > +	BUILD_BUG_ON_MSG((sizeof(struct prueth_swdata) > PRUETH_NAV_SW_DATA_SIZE),
> > +			 "insufficient SW_DATA size");
> > +
> >   	prueth = devm_kzalloc(dev, sizeof(*prueth), GFP_KERNEL);
> >   	if (!prueth)
> >   		return -ENOMEM;
> > diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.h b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
> > index c7b906de18af..3bbabd007129 100644
> > --- a/drivers/net/ethernet/ti/icssg/icssg_prueth.h
> > +++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
> > @@ -136,6 +136,22 @@ struct prueth_rx_chn {
> >   	struct page_pool *pg_pool;
> >   };
> >   
> > +enum prueth_swdata_type {
> > +	PRUETH_SWDATA_INVALID = 0,
> > +	PRUETH_SWDATA_SKB,
> > +	PRUETH_SWDATA_PAGE,
> > +	PRUETH_SWDATA_CMD,
>
> PRUETH_SWDATA_CMD is not beig used so let's use it in emac_send_command_sr1()

Yes, will do that. This is actually a miss in my previous patches.

> > +};
> > +
> > +struct prueth_swdata {
> > +	enum prueth_swdata_type type;
> > +	union prueth_data {
> > +		struct sk_buff *skb;
> > +		struct page *page;
> > +		u32 cmd;
> > +	} data;
> > +};
> > +
> >   /* There are 4 Tx DMA channels, but the highest priority is CH3 (thread 3)
> >    * and lower three are lower priority channels or threads.
> >    */
> > diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth_sr1.c b/drivers/net/ethernet/ti/icssg/icssg_prueth_sr1.c
> > index aeeb8a50376b..7bbe0808b3ec 100644
> > --- a/drivers/net/ethernet/ti/icssg/icssg_prueth_sr1.c
> > +++ b/drivers/net/ethernet/ti/icssg/icssg_prueth_sr1.c
> > @@ -275,10 +275,10 @@ static struct sk_buff *prueth_process_rx_mgm(struct prueth_emac *emac,
> >   	struct net_device *ndev = emac->ndev;
> >   	struct cppi5_host_desc_t *desc_rx;
> >   	struct page *page, *new_page;
> > +	struct prueth_swdata *swdata;
> >   	dma_addr_t desc_dma, buf_dma;
> >   	u32 buf_dma_len, pkt_len;
> >   	struct sk_buff *skb;
> > -	void **swdata;
> >   	void *pa;
> >   	int ret;
> >   
> > @@ -301,7 +301,7 @@ static struct sk_buff *prueth_process_rx_mgm(struct prueth_emac *emac,
> >   	}
> >   
> >   	swdata = cppi5_hdesc_get_swdata(desc_rx);
> > -	page = *swdata;
> > +	page = swdata->data.page;
> >   	cppi5_hdesc_get_obuf(desc_rx, &buf_dma, &buf_dma_len);
> >   	pkt_len = cppi5_hdesc_get_pktlen(desc_rx);
> >