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net: xilinx: axienet: Enqueue Tx packets in dql before dmaengine starts

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Enqueue packets in dql after dma engine starts causes race condition.
Tx transfer starts once dma engine is started and may execute dql dequeue
in completion before it gets queued. It results in following kernel crash
while running iperf stress test:

kernel BUG at lib/dynamic_queue_limits.c:99!
<snip>
Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
pc : dql_completed+0x238/0x248
lr : dql_completed+0x3c/0x248

Call trace:
  dql_completed+0x238/0x248
  axienet_dma_tx_cb+0xa0/0x170
  xilinx_dma_do_tasklet+0xdc/0x290
  tasklet_action_common+0xf8/0x11c
  tasklet_action+0x30/0x3c
  handle_softirqs+0xf8/0x230
<snip>

Start dmaengine after enqueue in dql fixes the crash.

Fixes: 6a91b846af ("net: axienet: Introduce dmaengine support")
Signed-off-by: Suraj Gupta <suraj.gupta2@amd.com>
Link: https://patch.msgid.link/20241030062533.2527042-2-suraj.gupta2@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Suraj Gupta 2024-10-30 11:55:32 +05:30 committed by Jakub Kicinski
parent be31ec5c8e
commit 5ccdcdf186
1 changed files with 2 additions and 2 deletions
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4
drivers/net/ethernet/xilinx/xilinx_axienet_main.c
View File

@ -924,13 +924,13 @@ axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev)
skbuf_dma->sg_len = sg_len;
dma_tx_desc->callback_param = lp;
dma_tx_desc->callback_result = axienet_dma_tx_cb;
dmaengine_submit(dma_tx_desc);
dma_async_issue_pending(lp->tx_chan);
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);
dmaengine_submit(dma_tx_desc);
dma_async_issue_pending(lp->tx_chan);
return NETDEV_TX_OK;
xmit_error_unmap_sg: