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[19.11,V3,03/12] net/e1000: fix Tx descriptor status api (igb)

Message ID 6fa4aa21b2ab176fcc767272f8ab3dc59907d5a1.1565252336.git.thierry.herbelot@6wind.com (mailing list archive)
State Superseded, archived
Headers show
Series Miscellaneous fixes | expand


Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation fail Compilation issues

Commit Message

Thierry Herbelot Aug. 8, 2019, 8:22 a.m. UTC
From: Olivier Matz <olivier.matz@6wind.com>

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: 978f8eea1719 ("net/e1000: implement descriptor status API (igb)")
Cc: stable@dpdk.org

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
 drivers/net/e1000/igb_rxtx.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
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diff --git a/drivers/net/e1000/igb_rxtx.c b/drivers/net/e1000/igb_rxtx.c
index c5606de5d7a0..c22118e59a21 100644
--- a/drivers/net/e1000/igb_rxtx.c
+++ b/drivers/net/e1000/igb_rxtx.c
@@ -1835,14 +1835,15 @@  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))