{bp-19589} net/tcp/tcp_send: Remove work_available check when updating retransmit timer - #19696
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…t timer The condition work_available(&conn->work) && tx_unacked != 0 prevented tcp_update_retrantimer from being called when the work queue was still busy, leaving conn->timer stale or zero on subsequent sends. This caused the RTT estimation to compute a false RTT (m = rto - 0 = rto), creating a positive feedback loop that inflated the RTO to extreme values (e.g., 232 half-seconds = ~116 seconds). Fix: remove the work_available check so that tcp_update_retrantimer is always called when there is unacknowledged data. The decision to re-queue the work is handled internally by tcp_update_timer. Signed-off-by: zhekunren <zhekunren@qq.com>
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xiaoxiang781216
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Aug 5, 2026
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Summary
The condition work_available(&conn->work) && tx_unacked != 0 prevented tcp_update_retrantimer from being called when the work queue was still busy, leaving conn->timer stale or zero on subsequent sends. This caused the RTT estimation to compute a false RTT (m = rto - 0 = rto), creating a positive feedback loop that inflated the RTO to extreme values (e.g., 232 half-seconds = ~116 seconds).
Fix: remove the work_available check so that tcp_update_retrantimer is always called when there is unacknowledged data. The decision to re-queue the work is handled internally by tcp_update_timer.
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