[PATCH] examples/ip_reassembly: remove conflicting Tx offload

[PATCH] examples/ip_reassembly: remove conflicting Tx offload

[Zhichao Zeng]

IP packet reassembly requires the MULTI_SEGS offload to be enabled in order
to handle fragmented packets across multiple memory segments. However, the
MBUF_FAST_FREE offload conflicts with MULTI_SEGS and cannot be enabled
simultaneously.

Remove the MBUF_FAST_FREE offload to avoid conflicts with MULTI_SEGS.

Fixes: 9df56e69ee3f ("examples/ip_reassembly: convert to new ethdev offloads API")
Cc: stable@dpdk.org

Signed-off-by: Zhichao Zeng <zhichaox.zeng@intel.com>
---
 examples/ip_reassembly/main.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/examples/ip_reassembly/main.c b/examples/ip_reassembly/main.c
index 17ae76d4ba..294fd38889 100644
--- a/examples/ip_reassembly/main.c
+++ b/examples/ip_reassembly/main.c
@@ -1093,9 +1093,6 @@ main(int argc, char **argv)
 		n_tx_queue = nb_lcores;
 		if (n_tx_queue > MAX_TX_QUEUE_PER_PORT)
 			n_tx_queue = MAX_TX_QUEUE_PER_PORT;
-		if (dev_info.tx_offload_capa & RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE)
-			local_port_conf.txmode.offloads |=
-				RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE;
 
 		local_port_conf.rx_adv_conf.rss_conf.rss_hf &=
 			dev_info.flow_type_rss_offloads;
-- 
2.34.1

RE: [PATCH] examples/ip_reassembly: remove conflicting Tx offload

[Konstantin Ananyev]

> 
> IP packet reassembly requires the MULTI_SEGS offload to be enabled in order
> to handle fragmented packets across multiple memory segments. However, the
> MBUF_FAST_FREE offload conflicts with MULTI_SEGS and cannot be enabled
> simultaneously.
> 
> Remove the MBUF_FAST_FREE offload to avoid conflicts with MULTI_SEGS.
> 
> Fixes: 9df56e69ee3f ("examples/ip_reassembly: convert to new ethdev offloads
> API")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Zhichao Zeng <zhichaox.zeng@intel.com>
> ---
>  examples/ip_reassembly/main.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/examples/ip_reassembly/main.c b/examples/ip_reassembly/main.c
> index 17ae76d4ba..294fd38889 100644
> --- a/examples/ip_reassembly/main.c
> +++ b/examples/ip_reassembly/main.c
> @@ -1093,9 +1093,6 @@ main(int argc, char **argv)
>  		n_tx_queue = nb_lcores;
>  		if (n_tx_queue > MAX_TX_QUEUE_PER_PORT)
>  			n_tx_queue = MAX_TX_QUEUE_PER_PORT;
> -		if (dev_info.tx_offload_capa &
> RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE)
> -			local_port_conf.txmode.offloads |=
> -				RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE;
> 
>  		local_port_conf.rx_adv_conf.rss_conf.rss_hf &=
>  			dev_info.flow_type_rss_offloads;
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>

> 2.34.1
> 

RE: [PATCH] examples/ip_reassembly: remove conflicting Tx offload

[Xu, HailinX]

> -----Original Message-----
> From: Zhichao Zeng <zhichaox.zeng@intel.com>
> Sent: Friday, September 19, 2025 3:12 PM
> To: dev@dpdk.org
> Cc: stable@dpdk.org; Zeng, ZhichaoX <zhichaox.zeng@intel.com>; Konstantin
> Ananyev <konstantin.ananyev@huawei.com>; Ferruh Yigit
> <ferruh.yigit@amd.com>; Shahaf Shuler <shahafs@nvidia.com>
> Subject: [PATCH] examples/ip_reassembly: remove conflicting Tx offload
> 
> IP packet reassembly requires the MULTI_SEGS offload to be enabled in order
> to handle fragmented packets across multiple memory segments. However,
> the MBUF_FAST_FREE offload conflicts with MULTI_SEGS and cannot be
> enabled simultaneously.
> 
> Remove the MBUF_FAST_FREE offload to avoid conflicts with MULTI_SEGS.
> 
> Fixes: 9df56e69ee3f ("examples/ip_reassembly: convert to new ethdev
> offloads API")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Zhichao Zeng <zhichaox.zeng@intel.com>
> ---
Tested-by: Xu, HailinX <hailinx.xu@intel.com>

Re: [PATCH] examples/ip_reassembly: remove conflicting Tx offload

[Stephen Hemminger]

On Fri, 19 Sep 2025 15:12:13 +0800
Zhichao Zeng <zhichaox.zeng@intel.com> wrote:

> IP packet reassembly requires the MULTI_SEGS offload to be enabled in order
> to handle fragmented packets across multiple memory segments. However, the
> MBUF_FAST_FREE offload conflicts with MULTI_SEGS and cannot be enabled
> simultaneously.
> 
> Remove the MBUF_FAST_FREE offload to avoid conflicts with MULTI_SEGS.
> 
> Fixes: 9df56e69ee3f ("examples/ip_reassembly: convert to new ethdev offloads API")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Zhichao Zeng <zhichaox.zeng@intel.com>
>

Later Tech Board discussion concluded that fast free and multi segs are not
conflicting flags. Dropping this patch.

RE: [PATCH] examples/ip_reassembly: remove conflicting Tx offload

[Morten Brørup]

+CC Bruce

> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> 
> On Fri, 19 Sep 2025 15:12:13 +0800
> Zhichao Zeng <zhichaox.zeng@intel.com> wrote:
> 
> > IP packet reassembly requires the MULTI_SEGS offload to be enabled in
> order
> > to handle fragmented packets across multiple memory segments.
> However, the
> > MBUF_FAST_FREE offload conflicts with MULTI_SEGS and cannot be
> enabled
> > simultaneously.
> >
> > Remove the MBUF_FAST_FREE offload to avoid conflicts with MULTI_SEGS.
> >
> > Fixes: 9df56e69ee3f ("examples/ip_reassembly: convert to new ethdev
> offloads API")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Zhichao Zeng <zhichaox.zeng@intel.com>
> >
> 
> Later Tech Board discussion concluded that fast free and multi segs are
> not
> conflicting flags. Dropping this patch.

Let's postpone rather than drop this patch.

The documentation still says that FAST_FREE does not allow segmented packets.
And it has been reported that some drivers fail when using both flags.
The Tech Board wishes to get rid of the mutual exclusivity, to support jumbo frames with FAST_FREE; but the mutual exclusivity is still under investigation, and no final conclusion has been reached yet.
For now, it has been concluded that the mbuf library is not the reason for mutual exclusivity, but it has not yet been concluded if is required for driver implementation purposes.