Commit d1978d03 authored by Suraj Gupta's avatar Suraj Gupta Committed by Paolo Abeni
Browse files

net: xilinx: axienet: Fix BQL accounting for multi-BD TX packets 



When a TX packet spans multiple buffer descriptors (scatter-gather),
axienet_free_tx_chain sums the per-BD actual length from descriptor
status into a caller-provided accumulator. That sum is reset on each
NAPI poll. If the BDs for a single packet complete across different
polls, the earlier bytes are lost and never credited to BQL. This
causes BQL to think bytes are permanently in-flight, eventually
stalling the TX queue.

The SKB pointer is stored only on the last BD of a packet. When that
BD completes, use skb->len for the byte count instead of summing
per-BD status lengths. This matches netdev_sent_queue(), which debits
skb->len, and naturally survives across polls because no partial
packet contributes to the accumulator.

Fixes: c900e49d ("net: xilinx: axienet: Implement BQL")
Signed-off-by: default avatarSuraj Gupta <suraj.gupta2@amd.com>
Reviewed-by: default avatarSean Anderson <sean.anderson@linux.dev>
Link: https://patch.msgid.link/20260327073238.134948-3-suraj.gupta2@amd.com


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 393e0b4f

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

+4 −5
Original line number Diff line number Diff line
@@ -770,8 +770,8 @@ static int axienet_device_reset(struct net_device *ndev) 
 * @first_bd:	Index of first descriptor to clean up

 * @nr_bds:	Max number of descriptors to clean up

 * @force:	Whether to clean descriptors even if not complete

 * @sizep:	Pointer to a u32 filled with the total sum of all bytes

 *		in all cleaned-up descriptors. Ignored if NULL.

 * @sizep:	Pointer to a u32 accumulating the total byte count of

 *		completed packets (using skb->len). Ignored if NULL.

 * @budget:	NAPI budget (use 0 when not called from NAPI poll)

 *

 * Would either be called after a successful transmit operation, or after
@@ -805,6 +805,8 @@ static int axienet_free_tx_chain(struct axienet_local *lp, u32 first_bd, 
				 DMA_TO_DEVICE);



		if (cur_p->skb && (status & XAXIDMA_BD_STS_COMPLETE_MASK)) {

			if (sizep)

				*sizep += cur_p->skb->len;

			napi_consume_skb(cur_p->skb, budget);

			packets++;

		}
@@ -818,9 +820,6 @@ static int axienet_free_tx_chain(struct axienet_local *lp, u32 first_bd, 
		wmb();

		cur_p->cntrl = 0;

		cur_p->status = 0;



		if (sizep)

			*sizep += status & XAXIDMA_BD_STS_ACTUAL_LEN_MASK;

	}



	if (!force) {