关于f-stack在bbr上的一个bug #1032

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1. jfb8856606 commented on Nov 27, 2025

   

   jfb8856606

   on Nov 27, 2025

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   Thank you for your testing and feedback.

   We checked the definition and usage of the function and it does appear to have an issue.

   We further examined the FreeBSD-release-13.0 branch code used by F-Stack, as well as the code of the upcoming FreeBSD release-15.0 branch, and found that there have been no modifications.

   We will conduct some further testing and provide feedback later, but it may take a considerable amount of time before we can proceed.
2. jfb8856606

   added a commit that references this issue on Mar 27, 2026

   fix(bbr): correct argument order in bbr_get_raw_target_cwnd calls

   ...

   This issue will close once commit 85e7ee0 is merged into the 'master' branch.

   85e7ee0
3. jfb8856606 commented on Mar 27, 2026

   

   jfb8856606

   on Mar 27, 2026

   Last edited by jfb8856606

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   We have confirmed the bug and submitted a fix: #1058

   The root cause is that both call sites in bbr_get_target_cwnd and bbr_get_a_state_target passed bw and gain in the wrong order to bbr_get_raw_target_cwnd. This caused bw (uint64_t) to be truncated to uint32_t and used as the gain multiplier, while the small gain value was used as the bandwidth, resulting in a severely underestimated congestion window.

   This is an upstream FreeBSD bug (present in all FreeBSD versions including releng/13.0 through releng/15.0 and main). We are fixing it in F-Stack first. Thank you for the detailed report!
4. jfb8856606

   added 2 commits that reference this issue on Mar 27, 2026

   fix(bbr): correct argument order in bbr_get_raw_target_cwnd calls

   ...

   This issue will close once commit 8c3808f is merged into the 'master' branch.

   8c3808f

   fix(bbr): correct argument order in bbr_get_raw_target_cwnd calls

   ...

   This issue will close once commit 74301b2 is merged into the 'dev' branch.

   74301b2
5. jfb8856606

   closed this as completedin #1058on Mar 27, 2026
6. jfb8856606

   added a commit that references this issue on Mar 27, 2026

   fix(bbr): correct argument order in bbr_get_raw_target_cwnd calls

   ...

   This issue will close once commit 7bc9468 is merged into the 'dev' branch.

   7bc9468