net: xilinx: axienet: Fix Tx skb circular buffer occupancy check in dmaengine xmit

[PATCH net] net: xilinx: axienet: Fix Tx skb circular buffer occupancy check in dmaengine xmit

Posted by Suraj Gupta 6 months, 3 weeks ago

In Dmaengine flow, driver maintains struct skbuf_dma_descriptor rings each
element of which corresponds to a skb. In Tx datapath, compare available
space in skb ring with number of skbs instead of skb fragments.
Replace x * (MAX_SKB_FRAGS) in netif_txq_completed_wake() and
netif_txq_maybe_stop() with x * (1 skb) to fix the comparison.

Fixes: 6a91b846af85 ("net: axienet: Introduce dmaengine support")
Signed-off-by: Suraj Gupta <suraj.gupta2@amd.com>
---
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 1b7a653c1f4e..6011d7eae0c7 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -880,7 +880,7 @@ static void axienet_dma_tx_cb(void *data, const struct dmaengine_result *result)
 	dev_consume_skb_any(skbuf_dma->skb);
 	netif_txq_completed_wake(txq, 1, len,
 				 CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX),
-				 2 * MAX_SKB_FRAGS);
+				 2);
 }
 
 /**
@@ -914,7 +914,7 @@ axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev)
 
 	dma_dev = lp->tx_chan->device;
 	sg_len = skb_shinfo(skb)->nr_frags + 1;
-	if (CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX) <= sg_len) {
+	if (CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX) <= 1) {
 		netif_stop_queue(ndev);
 		if (net_ratelimit())
 			netdev_warn(ndev, "TX ring unexpectedly full\n");
@@ -964,7 +964,7 @@ axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev)
 	txq = skb_get_tx_queue(lp->ndev, skb);
 	netdev_tx_sent_queue(txq, skb->len);
 	netif_txq_maybe_stop(txq, CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX),
-			     MAX_SKB_FRAGS + 1, 2 * MAX_SKB_FRAGS);
+			     1, 2);
 
 	dmaengine_submit(dma_tx_desc);
 	dma_async_issue_pending(lp->tx_chan);
-- 
2.25.1

Re: [PATCH net] net: xilinx: axienet: Fix Tx skb circular buffer occupancy check in dmaengine xmit

Posted by Sean Anderson 6 months, 3 weeks ago

On 5/21/25 14:16, Suraj Gupta wrote:
> In Dmaengine flow, driver maintains struct skbuf_dma_descriptor rings each
> element of which corresponds to a skb. In Tx datapath, compare available
> space in skb ring with number of skbs instead of skb fragments.
> Replace x * (MAX_SKB_FRAGS) in netif_txq_completed_wake() and
> netif_txq_maybe_stop() with x * (1 skb) to fix the comparison.
> 
> Fixes: 6a91b846af85 ("net: axienet: Introduce dmaengine support")
> Signed-off-by: Suraj Gupta <suraj.gupta2@amd.com>
> ---
>  drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> index 1b7a653c1f4e..6011d7eae0c7 100644
> --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> @@ -880,7 +880,7 @@ static void axienet_dma_tx_cb(void *data, const struct dmaengine_result *result)
>  	dev_consume_skb_any(skbuf_dma->skb);
>  	netif_txq_completed_wake(txq, 1, len,
>  				 CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX),
> -				 2 * MAX_SKB_FRAGS);
> +				 2);
>  }
>  
>  /**
> @@ -914,7 +914,7 @@ axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev)
>  
>  	dma_dev = lp->tx_chan->device;
>  	sg_len = skb_shinfo(skb)->nr_frags + 1;
> -	if (CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX) <= sg_len) {
> +	if (CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX) <= 1) {
>  		netif_stop_queue(ndev);
>  		if (net_ratelimit())
>  			netdev_warn(ndev, "TX ring unexpectedly full\n");
> @@ -964,7 +964,7 @@ axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev)
>  	txq = skb_get_tx_queue(lp->ndev, skb);
>  	netdev_tx_sent_queue(txq, skb->len);
>  	netif_txq_maybe_stop(txq, CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX),
> -			     MAX_SKB_FRAGS + 1, 2 * MAX_SKB_FRAGS);
> +			     1, 2);
>  
>  	dmaengine_submit(dma_tx_desc);
>  	dma_async_issue_pending(lp->tx_chan);

Reviwed-by: Sean Anderson <sean.anderson@linux.dev>

Re: [PATCH net] net: xilinx: axienet: Fix Tx skb circular buffer occupancy check in dmaengine xmit

Posted by Sean Anderson 6 months, 3 weeks ago

On 5/23/25 12:20, Sean Anderson wrote:
> On 5/21/25 14:16, Suraj Gupta wrote:
>> In Dmaengine flow, driver maintains struct skbuf_dma_descriptor rings each
>> element of which corresponds to a skb. In Tx datapath, compare available
>> space in skb ring with number of skbs instead of skb fragments.
>> Replace x * (MAX_SKB_FRAGS) in netif_txq_completed_wake() and
>> netif_txq_maybe_stop() with x * (1 skb) to fix the comparison.
>> 
>> Fixes: 6a91b846af85 ("net: axienet: Introduce dmaengine support")
>> Signed-off-by: Suraj Gupta <suraj.gupta2@amd.com>
>> ---
>>  drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>> 
>> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
>> index 1b7a653c1f4e..6011d7eae0c7 100644
>> --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
>> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
>> @@ -880,7 +880,7 @@ static void axienet_dma_tx_cb(void *data, const struct dmaengine_result *result)
>>  	dev_consume_skb_any(skbuf_dma->skb);
>>  	netif_txq_completed_wake(txq, 1, len,
>>  				 CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX),
>> -				 2 * MAX_SKB_FRAGS);
>> +				 2);
>>  }
>>  
>>  /**
>> @@ -914,7 +914,7 @@ axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev)
>>  
>>  	dma_dev = lp->tx_chan->device;
>>  	sg_len = skb_shinfo(skb)->nr_frags + 1;
>> -	if (CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX) <= sg_len) {
>> +	if (CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX) <= 1) {
>>  		netif_stop_queue(ndev);
>>  		if (net_ratelimit())
>>  			netdev_warn(ndev, "TX ring unexpectedly full\n");
>> @@ -964,7 +964,7 @@ axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev)
>>  	txq = skb_get_tx_queue(lp->ndev, skb);
>>  	netdev_tx_sent_queue(txq, skb->len);
>>  	netif_txq_maybe_stop(txq, CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX),
>> -			     MAX_SKB_FRAGS + 1, 2 * MAX_SKB_FRAGS);
>> +			     1, 2);
>>  
>>  	dmaengine_submit(dma_tx_desc);
>>  	dma_async_issue_pending(lp->tx_chan);
> 
> Reviwed-by: Sean Anderson <sean.anderson@linux.dev>

Reviewed-by: Sean Anderson <sean.anderson@linux.dev>

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