6.15-stable review patch. If anyone has any objections, please let me know.
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From: Jason Xing kernelxing@tencent.com
[ Upstream commit 3b7c13dfdcc26a78756cc17a23cdf4310c5a24a9 ]
There is no break time in the while() loop, so every time at the end of igb_xmit_zc(), negative overflow of nb_pkts will occur, which renders the return value always false. But theoretically, the result should be set after calling xsk_tx_peek_release_desc_batch(). We can take i40e_xmit_zc() as a good example.
Returning false means we're not done with transmission and we need one more poll, which is exactly what igb_xmit_zc() always did before this patch. After this patch, the return value depends on the nb_pkts value. Two cases might happen then: 1. if (nb_pkts < budget), it means we process all the possible data, so return true and no more necessary poll will be triggered because of this. 2. if (nb_pkts == budget), it means we might have more data, so return false to let another poll run again.
Fixes: f8e284a02afc ("igb: Add AF_XDP zero-copy Tx support") Signed-off-by: Jason Xing kernelxing@tencent.com Reviewed-by: Aleksandr Loktionov aleksandr.loktionov@intel.com Link: https://patch.msgid.link/20250723142327.85187-3-kerneljasonxing@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/intel/igb/igb_xsk.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/intel/igb/igb_xsk.c b/drivers/net/ethernet/intel/igb/igb_xsk.c index 157d43787fa0..02935d4e1140 100644 --- a/drivers/net/ethernet/intel/igb/igb_xsk.c +++ b/drivers/net/ethernet/intel/igb/igb_xsk.c @@ -481,7 +481,7 @@ bool igb_xmit_zc(struct igb_ring *tx_ring, struct xsk_buff_pool *xsk_pool) if (!nb_pkts) return true;
- while (nb_pkts-- > 0) { + for (; i < nb_pkts; i++) { dma = xsk_buff_raw_get_dma(xsk_pool, descs[i].addr); xsk_buff_raw_dma_sync_for_device(xsk_pool, dma, descs[i].len);
@@ -511,7 +511,6 @@ bool igb_xmit_zc(struct igb_ring *tx_ring, struct xsk_buff_pool *xsk_pool)
total_bytes += descs[i].len;
- i++; tx_ring->next_to_use++; tx_buffer_info->next_to_watch = tx_desc; if (tx_ring->next_to_use == tx_ring->count)