On Sat, 10 Dec 2022 00:32:07 +0100 Daniel Borkmann wrote: > fwiw, these should not be necessary, Documentation/RCU/checklist.rst : > > [...] One example of non-obvious pairing is the XDP feature in networking, > which calls BPF programs from network-driver NAPI (softirq) context. BPF > relies heavily on RCU protection for its data structures, but because the > BPF program invocation happens entirely within a single local_bh_disable() > section in a NAPI poll cycle, this usage is safe. The reason that this usage > is safe is that readers can use anything that disables BH when updaters use > call_rcu() or synchronize_rcu(). [...] FWIW I sent a link to the thread to Paul and he confirmed the RCU will wait for just the BH.
