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October 2023

4 participants
12 discussions

[PATCH 0/4] RFC: Updates for cppcheck-2.12 warnings
by David Gibson 05 Oct '23

05 Oct '23

cppcheck 2.12 (which Fedora 38 has updated, for one) introduces a number of new warnings. Unfortunately, at least one of these is a clear bug in cppcheck. This series fixes a number of the new warnings reported in passt (patches 1..3) and works around the remaining cppcheck bug (patch 4). I'm pretty confident that patches 1 & 2 are safe and beneficial to apply regardless of which cppcheck we're using. Patch 3 is a little more dubious, because it potentially increases the cppcheck runtime. On my system it doesn't seem to make a significant difference, but that might not always stay true. Patch 4 is a tricky one. It applies a specific suppression to work around the cppcheck bug. That's necessary to get a pass with the currently available cppcheck. However, it's ugly and we'd like to remove it once the bug is fixed, but have no obvious way to remind us to do that. What we want to do here kind of depends how long it takes the bug to be fixed, which isn't clear at the moment. David Gibson (4): cppcheck: Make many pointers const conf: Remove overly cryptic selection of forward table cppcheck: Use "exhaustive" level checking when available cppcheck: Work around bug in cppcheck 2.12.0 Makefile | 6 ++++++ conf.c | 25 +++++++++++-------------- isolation.c | 2 +- isolation.h | 2 +- log.c | 6 +++--- netlink.c | 6 +++--- netlink.h | 6 +++--- pasta.c | 4 ++-- pasta.h | 2 +- tap.c | 14 +++++++------- tap.h | 6 +++--- tcp.c | 25 ++++++++++++++++--------- tcp_conn.h | 2 +- tcp_splice.c | 5 +++-- tcp_splice.h | 3 ++- udp.c | 4 ++-- udp.h | 2 +- util.c | 5 +++-- util.h | 4 ++-- 19 files changed, 71 insertions(+), 58 deletions(-) -- 2.41.0

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[PATCH v2 0/3] Fixes and a workaround for TCP stalls with small buffers
by Stefano Brivio 03 Oct '23

03 Oct '23

The fundamental patch here is 2/3, which is a workaround for a rather surprising kernel behaviour we seem to be hitting. This all comes from the investigation around https://bugs.passt.top/show_bug.cgi?id=74. I can't hit stalls anymore and throughput looks finally good to me (~3.5gbps with 208 KiB rmem_max and wmem_max), but... please test (again). v2: - Drop 1/5 (checking for ACK before resetting STALLED and calling tcp_data_from_sock() directly from tcp_tap_handler()) - Moving reset of STALLED flag is now done in 2/3 (was 3/5) - Don't pass unnecessary argument to tcp_data_to_tap() in 3/3 (was 4/5) - Drop 5/5 as long as we're not sure what kind of buffer clamping is actually beneficial Stefano Brivio (3): tcp: Fix comment to tcp_sock_consume() tcp: Force TCP_WINDOW_CLAMP before resetting STALLED flag tcp, tap: Don't increase tap-side sequence counter for dropped frames tap.c | 10 ++++++--- tap.h | 2 +- tcp.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++---------- 3 files changed, 67 insertions(+), 16 deletions(-) -- 2.39.2

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