Commit 485ec2ea authored Jan 23, 2020 by Amol Grover Committed by Daniel Borkmann Jan 23, 2020

bpf, devmap: Pass lockdep expression to RCU lists

head is traversed using hlist_for_each_entry_rcu outside an RCU
read-side critical section but under the protection of dtab->index_lock.

Hence, add corresponding lockdep expression to silence false-positive
lockdep warnings, and harden RCU lists.

Fixes: 6f9d451a ("xdp: Add devmap_hash map type for looking up devices by hashed index")
Signed-off-by: Amol Grover <frextrite@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20200123120437.26506-1-frextrite@gmail.com

parent fd786fb1

kernel/bpf/devmap.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -263,7 +263,8 @@ struct bpf_dtab_netdev __dev_map_hash_lookup_elem(struct bpf_map map, u32 key)
		struct hlist_head *head = dev_map_index_hash(dtab, key);
		struct bpf_dtab_netdev *dev;

		hlist_for_each_entry_rcu(dev, head, index_hlist)
		hlist_for_each_entry_rcu(dev, head, index_hlist,
		lockdep_is_held(&dtab->index_lock))
		if (dev->idx == key)
		return dev;