Re: [PATCH net] tcp: fix icsk_ack.ato bitfield overflow

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@xxxxxxxxxx>:

On Fri,  7 Aug 2026 09:44:36 +0800 you wrote:
> On cross-region connections we observed delayed ACKs suddenly turning
> into immediate ACKs plus a TCP_MAX_QUICKACKS burst, as if the
> connection had just received its first data segment.
> 
> Commit 95b9a87c6a6b ("tcp: record last received ipv6 flowlabel")
> squeezed icsk_ack.ato into 8 bits, sized for TCP_DELACK_MAX. But both
> writers still bound ato by icsk_rto, which can be well above 255
> jiffies, so the bitfield assignment silently wraps mod 256: repeated
> delack timer misses double ato up to icsk_rto, storing 320 as 64 and
> 256 as 0, and ato == 0 is the "first data packet" sentinel in
> tcp_event_data_recv().
> 
> [...]

Here is the summary with links:
  - [net] tcp: fix icsk_ack.ato bitfield overflow
    https://git.kernel.org/netdev/net/c/60837e4b840a

You are awesome, thank you!
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