Toke Høiland-Jørgensen 694cea395f bpf: Allow RCU-protected lookups to happen from bh context
XDP programs are called from a NAPI poll context, which means the RCU
reference liveness is ensured by local_bh_disable(). Add
rcu_read_lock_bh_held() as a condition to the RCU checks for map lookups so
lockdep understands that the dereferences are safe from inside *either* an
rcu_read_lock() section *or* a local_bh_disable() section. While both
bh_disabled and rcu_read_lock() provide RCU protection, they are
semantically distinct, so we need both conditions to prevent lockdep
complaints.

This change is done in preparation for removing the redundant
rcu_read_lock()s from drivers.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210624160609.292325-5-toke@redhat.com
2021-06-24 19:41:15 +02:00
2021-06-13 13:49:39 -07:00
2021-05-23 11:42:48 -10:00

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