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Eric Dumazet
ea25e03da7
codel_dump_stats() only runs with RTNL held,
reading fields that can be changed in qdisc fast path.
Add READ_ONCE()/WRITE_ONCE() annotations.
Alternative would be to acquire the qdisc spinlock, but our long-term
goal is to make qdisc dump operations lockless as much as we can.
tc_codel_xstats fields don't need to be latched atomically,
otherwise this bug would have been caught earlier.
No change in kernel size:
$ scripts/bloat-o-meter -t vmlinux.0 vmlinux
add/remove: 0/0 grow/shrink: 1/1 up/down: 3/-1 (2)
Function old new delta
codel_qdisc_dequeue 2462 2465 +3
codel_dump_stats 250 249 -1
Total: Before=29739919, After=29739921, chg +0.00%
Fixes: 76e3cc126b ("codel: Controlled Delay AQM")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260407143053.1570620-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>