From de0ae4440ad84edc4eb6892eb2a618712d32fa78 Mon Sep 17 00:00:00 2001 From: Olivier Matz Date: Mon, 25 Jun 2018 15:34:48 +0200 Subject: [PATCH] net/igb: fix Tx descriptor status api The Tx descriptor status api was not behaving as expected. This API is used to inspect the content of the descriptors in the Tx ring to determine the length of the Tx queue. Since the software advances the tail pointer and the hardware advances the head pointer, the Tx queue is located before txq->tx_tail in the ring. Therefore, a call to rte_eth_tx_descriptor_status(..., offset=20) should inspect the 20th descriptor before the tail, not after. Fixes: 7d499cb15e8a ("net/igb: implement descriptor status API") Signed-off-by: Olivier Matz Signed-off-by: Didier Pallard --- drivers/net/e1000/igb_rxtx.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/net/e1000/igb_rxtx.c b/drivers/net/e1000/igb_rxtx.c index 5f729f2710..22ca364e56 100644 --- a/drivers/net/e1000/igb_rxtx.c +++ b/drivers/net/e1000/igb_rxtx.c @@ -1826,14 +1826,15 @@ eth_igb_tx_descriptor_status(void *tx_queue, uint16_t offset) { struct igb_tx_queue *txq = tx_queue; volatile uint32_t *status; - uint32_t desc; + int32_t desc; if (unlikely(offset >= txq->nb_tx_desc)) return -EINVAL; - desc = txq->tx_tail + offset; - if (desc >= txq->nb_tx_desc) - desc -= txq->nb_tx_desc; + desc = txq->tx_tail - offset - 1; + if (desc < 0) + desc += txq->nb_tx_desc; + desc = txq->sw_ring[desc].last_id; status = &txq->tx_ring[desc].wb.status; if (*status & rte_cpu_to_le_32(E1000_TXD_STAT_DD)) -- 2.39.5