On Mon, Oct 07, 2024 at 01:24:35PM -0700, Joshua Hay wrote:
> Commit d9028db618a6 ("idpf: convert to libeth Tx buffer completion")
> inadvertently removed code that was necessary for the tx buffer cleaning
> routine to iterate over all buffers associated with a packet.
>
> When a frag is too large for a single data descriptor, it will be split
> across multiple data descriptors. This means the frag will span multiple
> buffers in the buffer ring in order to keep the descriptor and buffer
> ring indexes aligned. The buffer entries in the ring are technically
> empty and no cleaning actions need to be performed. These empty buffers
> can precede other frags associated with the same packet. I.e. a single
> packet on the buffer ring can look like:
>
> buf[0]=skb0.frag0
> buf[1]=skb0.frag1
> buf[2]=empty
> buf[3]=skb0.frag2
>
> The cleaning routine iterates through these buffers based on a matching
> completion tag. If the completion tag is not set for buf2, the loop will
> end prematurely. Frag2 will be left uncleaned and next_to_clean will be
> left pointing to the end of packet, which will break the cleaning logic
> for subsequent cleans. This consequently leads to tx timeouts.
>
> Assign the empty bufs the same completion tag for the packet to ensure
> the cleaning routine iterates over all of the buffers associated with
> the packet.
>
> Fixes: d9028db618a6 ("idpf: convert to libeth Tx buffer completion")
> Signed-off-by: Joshua Hay <[email protected]>
> Acked-by: Alexander Lobakin <[email protected]>
> Reviewed-by: Madhu chittim <[email protected]>
Thanks for the detailed description.
Reviewed-by: Simon Horman <[email protected]>
