ACK: [PATCH v1 0/1] [SRU][J:linux-bluefield] platform/mellanox: mlxbf-tmfifo: Drop Tx network packet when Tx TmFIFO is full

[Andrei Gherzan]

On 24/01/31 01:32PM, Liming Sun wrote:
> BugLink: https://bugs.launchpad.net/bugs/2051871
> 
> SRU Justification:
> 
> [Impact]
> This is a cherry-pick fix from upstream to drop Tx network packet
> when Tx TmFIFO is full.
> 
> [Fix]
> Starting from Linux 5.16 kernel, Tx timeout mechanism was added
> in the virtio_net driver which prints the "Tx timeout" warning
> message when a packet stays in Tx queue for too long. Below is an
> example of the reported message:
> 
> "[494105.316739] virtio_net virtio1 tmfifo_net0: TX timeout on
> queue: 0, sq: output.0, vq: 0×1, name: output.0, usecs since
> last trans: 3079892256".
> 
> This issue could happen when external host driver which drains the
> FIFO is restared, stopped or upgraded. To avoid such confusing
> "Tx timeout" messages, this commit adds logic to drop the outstanding
> Tx packet if it's not able to transmit in two seconds due to Tx FIFO
> full, which can be considered as congestion or out-of-resource drop.
> 
> This commit also handles the special case that the packet is half-
> transmitted into the Tx FIFO. In such case, the packet is discarded
> with remaining length stored in vring->rem_padding. So paddings with
> zeros can be sent out when Tx space is available to maintain the
> integrity of the packet format. The padded packet will be dropped on
> the receiving side.
> 
> [Test Case]
> Same functionality and testing as on BlueField-1/2/3. No functionality
> change.
> 
> [Regression Potential]
> Same behavior from user perspective.
> 
> [Other]
> n/a
> 
> 
> Liming Sun (1):
>   [SRU][J:linux-bluefield] platform/mellanox: mlxbf-tmfifo: Drop Tx
>     network packet when Tx TmFIFO is full
> 
>  drivers/platform/mellanox/mlxbf-tmfifo.c | 67 ++++++++++++++++++++++++
>  1 file changed, 67 insertions(+)

Acked-by: Andrei Gherzan <andrei.gherzan at canonical.com>

-- 
Andrei Gherzan
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