[PATCH] drivers/net: fix Tx packet prepare

[PATCH] drivers/net: fix Tx packet prepare

[Thomas Monjalon]

After removing callback checks from ethdev fast path,
some drivers crashed because tx_pkt_prepare was set to NULL.

Some drivers (hns3, ngbe, txgbe) need to use rte_eth_tx_pkt_prepare_dummy
when configuring queues.
Other drivers (ntnic, softnic) does not need to set tx_pkt_prepare
as it was set by eth_dev_set_dummy_fops() called by rte_eth_dev_allocate().

Bugzilla ID: 1834
Fixes: 066f3d9cc21c ("ethdev: remove callback checks from fast path")

Reported-by: Jiawen Wu <jiawenwu@trustnetic.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
---
 drivers/net/hns3/hns3_rxtx.c          | 4 ++--
 drivers/net/ngbe/ngbe_rxtx.c          | 2 +-
 drivers/net/ntnic/ntnic_ethdev.c      | 1 -
 drivers/net/softnic/rte_eth_softnic.c | 1 -
 drivers/net/txgbe/txgbe_rxtx.c        | 2 +-
 5 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/net/hns3/hns3_rxtx.c b/drivers/net/hns3/hns3_rxtx.c
index df703134be..3a99923220 100644
--- a/drivers/net/hns3/hns3_rxtx.c
+++ b/drivers/net/hns3/hns3_rxtx.c
@@ -4561,7 +4561,7 @@ hns3_set_rxtx_function(struct rte_eth_dev *eth_dev)
 	} else {
 		eth_dev->rx_pkt_burst = rte_eth_pkt_burst_dummy;
 		eth_dev->tx_pkt_burst = rte_eth_pkt_burst_dummy;
-		eth_dev->tx_pkt_prepare = NULL;
+		eth_dev->tx_pkt_prepare = rte_eth_tx_pkt_prepare_dummy;
 	}
 
 	hns3_trace_rxtx_function(eth_dev);
@@ -4917,7 +4917,7 @@ void
 hns3_stop_tx_datapath(struct rte_eth_dev *dev)
 {
 	dev->tx_pkt_burst = rte_eth_pkt_burst_dummy;
-	dev->tx_pkt_prepare = NULL;
+	dev->tx_pkt_prepare = rte_eth_tx_pkt_prepare_dummy;
 	hns3_eth_dev_fp_ops_config(dev);
 
 	if (rte_eal_process_type() == RTE_PROC_SECONDARY)
diff --git a/drivers/net/ngbe/ngbe_rxtx.c b/drivers/net/ngbe/ngbe_rxtx.c
index 66d72c88df..91e215694c 100644
--- a/drivers/net/ngbe/ngbe_rxtx.c
+++ b/drivers/net/ngbe/ngbe_rxtx.c
@@ -1921,7 +1921,7 @@ ngbe_set_tx_function(struct rte_eth_dev *dev, struct ngbe_tx_queue *txq)
 	if (txq->offloads == 0 &&
 			txq->tx_free_thresh >= RTE_PMD_NGBE_TX_MAX_BURST) {
 		PMD_INIT_LOG(DEBUG, "Using simple tx code path");
-		dev->tx_pkt_prepare = NULL;
+		dev->tx_pkt_prepare = rte_eth_tx_pkt_prepare_dummy;
 		if (txq->tx_free_thresh <= RTE_NGBE_TX_MAX_FREE_BUF_SZ &&
 				rte_vect_get_max_simd_bitwidth() >= RTE_VECT_SIMD_128 &&
 				(rte_eal_process_type() != RTE_PROC_PRIMARY ||
diff --git a/drivers/net/ntnic/ntnic_ethdev.c b/drivers/net/ntnic/ntnic_ethdev.c
index 23c3452d2d..89e751e7e0 100644
--- a/drivers/net/ntnic/ntnic_ethdev.c
+++ b/drivers/net/ntnic/ntnic_ethdev.c
@@ -2561,7 +2561,6 @@ nthw_pci_dev_init(struct rte_pci_device *pci_dev)
 		NT_LOG_DBGX(DBG, NTNIC, "Setting up RX functions for SCG");
 		eth_dev->rx_pkt_burst = eth_dev_rx_scg;
 		eth_dev->tx_pkt_burst = eth_dev_tx_scg;
-		eth_dev->tx_pkt_prepare = NULL;
 
 		struct rte_eth_link pmd_link;
 		pmd_link.link_speed = RTE_ETH_SPEED_NUM_NONE;
diff --git a/drivers/net/softnic/rte_eth_softnic.c b/drivers/net/softnic/rte_eth_softnic.c
index 91a1c3a98e..868e194509 100644
--- a/drivers/net/softnic/rte_eth_softnic.c
+++ b/drivers/net/softnic/rte_eth_softnic.c
@@ -312,7 +312,6 @@ pmd_ethdev_register(struct rte_vdev_device *vdev,
 	/* dev */
 	dev->rx_pkt_burst = pmd_rx_pkt_burst;
 	dev->tx_pkt_burst = pmd_tx_pkt_burst;
-	dev->tx_pkt_prepare = NULL;
 	dev->dev_ops = &pmd_ops;
 	dev->device = &vdev->device;
 
diff --git a/drivers/net/txgbe/txgbe_rxtx.c b/drivers/net/txgbe/txgbe_rxtx.c
index 78199ea00b..e2cd9b8841 100644
--- a/drivers/net/txgbe/txgbe_rxtx.c
+++ b/drivers/net/txgbe/txgbe_rxtx.c
@@ -2344,7 +2344,7 @@ txgbe_set_tx_function(struct rte_eth_dev *dev, struct txgbe_tx_queue *txq)
 #endif
 			txq->tx_free_thresh >= RTE_PMD_TXGBE_TX_MAX_BURST) {
 		PMD_INIT_LOG(DEBUG, "Using simple tx code path");
-		dev->tx_pkt_prepare = NULL;
+		dev->tx_pkt_prepare = rte_eth_tx_pkt_prepare_dummy;
 		if (txq->tx_free_thresh <= RTE_TXGBE_TX_MAX_FREE_BUF_SZ &&
 				rte_vect_get_max_simd_bitwidth() >= RTE_VECT_SIMD_128 &&
 				(rte_eal_process_type() != RTE_PROC_PRIMARY ||
-- 
2.51.0

RE: [PATCH] drivers/net: fix Tx packet prepare

[Morten Brørup]

> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> Sent: Wednesday, 19 November 2025 14.04
> 
> After removing callback checks from ethdev fast path,
> some drivers crashed because tx_pkt_prepare was set to NULL.
> 
> Some drivers (hns3, ngbe, txgbe) need to use
> rte_eth_tx_pkt_prepare_dummy
> when configuring queues.
> Other drivers (ntnic, softnic) does not need to set tx_pkt_prepare
> as it was set by eth_dev_set_dummy_fops() called by
> rte_eth_dev_allocate().
> 
> Bugzilla ID: 1834
> Fixes: 066f3d9cc21c ("ethdev: remove callback checks from fast path")
> 
> Reported-by: Jiawen Wu <jiawenwu@trustnetic.com>
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> ---

Searching for "tx_pkt_prepare = NULL;" finds a few more, but they are all in driver cleanup functions, so...
Reviewed-by: Morten Brørup <mb@smartsharesystems.com>

Re: [PATCH] drivers/net: fix Tx packet prepare

[Thomas Monjalon]

19/11/2025 14:19, Morten Brørup:
> > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > Sent: Wednesday, 19 November 2025 14.04
> > 
> > After removing callback checks from ethdev fast path,
> > some drivers crashed because tx_pkt_prepare was set to NULL.
> > 
> > Some drivers (hns3, ngbe, txgbe) need to use
> > rte_eth_tx_pkt_prepare_dummy
> > when configuring queues.
> > Other drivers (ntnic, softnic) does not need to set tx_pkt_prepare
> > as it was set by eth_dev_set_dummy_fops() called by
> > rte_eth_dev_allocate().
> > 
> > Bugzilla ID: 1834
> > Fixes: 066f3d9cc21c ("ethdev: remove callback checks from fast path")
> > 
> > Reported-by: Jiawen Wu <jiawenwu@trustnetic.com>
> > Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> > ---
> 
> Searching for "tx_pkt_prepare = NULL;" finds a few more, but they are all in driver cleanup functions, so...
> Reviewed-by: Morten Brørup <mb@smartsharesystems.com>

Yes I am working on the cleanup side.
But there is no bug in cleanup, it will be a cleanup of cleanup ;)
So cleanup will be handled after 25.11 release.

RE: [PATCH] drivers/net: fix Tx packet prepare

[Morten Brørup]

> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> Sent: Wednesday, 19 November 2025 14.44
> 
> 19/11/2025 14:19, Morten Brørup:
> > > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > > Sent: Wednesday, 19 November 2025 14.04
> > >
> > > After removing callback checks from ethdev fast path,
> > > some drivers crashed because tx_pkt_prepare was set to NULL.
> > >
> > > Some drivers (hns3, ngbe, txgbe) need to use
> > > rte_eth_tx_pkt_prepare_dummy
> > > when configuring queues.
> > > Other drivers (ntnic, softnic) does not need to set tx_pkt_prepare
> > > as it was set by eth_dev_set_dummy_fops() called by
> > > rte_eth_dev_allocate().
> > >
> > > Bugzilla ID: 1834
> > > Fixes: 066f3d9cc21c ("ethdev: remove callback checks from fast
> path")
> > >
> > > Reported-by: Jiawen Wu <jiawenwu@trustnetic.com>
> > > Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> > > ---
> >
> > Searching for "tx_pkt_prepare = NULL;" finds a few more, but they are
> all in driver cleanup functions, so...
> > Reviewed-by: Morten Brørup <mb@smartsharesystems.com>
> 
> Yes I am working on the cleanup side.
> But there is no bug in cleanup, it will be a cleanup of cleanup ;)

Agree.
I should have been more clear in my review comment:
The ones I found in driver cleanup functions don't cause problems, so I consider this patch complete.

> So cleanup will be handled after 25.11 release.
>