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* [PATCH bpf-next v2] bpf/devmap: convert remaining READ_ONCE() to rcu_dereference_check()
@ 2021-06-29  9:39 Toke Høiland-Jørgensen
  2021-06-30  0:08 ` Martin KaFai Lau
  2021-07-01  7:30 ` patchwork-bot+netdevbpf
  0 siblings, 2 replies; 3+ messages in thread
From: Toke Høiland-Jørgensen @ 2021-06-29  9:39 UTC (permalink / raw)
  To: bpf, netdev
  Cc: Martin KaFai Lau, Hangbin Liu, Jesper Dangaard Brouer,
	Magnus Karlsson, Paul E . McKenney, Jakub Kicinski,
	Toke Høiland-Jørgensen, kernel test robot

There were a couple of READ_ONCE()-invocations left-over by the devmap RCU
conversion. Convert these to rcu_dereference_check() as well to avoid
complaints from sparse.

v2:
 - Use rcu_dereference_check()

Fixes: 782347b6bcad ("xdp: Add proper __rcu annotations to redirect map entries")
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 kernel/bpf/devmap.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 2f6bd75cd682..e4ebe70cf201 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -558,7 +558,8 @@ int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
 
 	if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
 		for (i = 0; i < map->max_entries; i++) {
-			dst = READ_ONCE(dtab->netdev_map[i]);
+			dst = rcu_dereference_check(dtab->netdev_map[i],
+						    rcu_read_lock_bh_held());
 			if (!is_valid_dst(dst, xdp, exclude_ifindex))
 				continue;
 
@@ -654,7 +655,8 @@ int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
 
 	if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
 		for (i = 0; i < map->max_entries; i++) {
-			dst = READ_ONCE(dtab->netdev_map[i]);
+			dst = rcu_dereference_check(dtab->netdev_map[i],
+						    rcu_read_lock_bh_held());
 			if (!dst || dst->dev->ifindex == exclude_ifindex)
 				continue;
 
-- 
2.32.0


^ permalink raw reply	[flat|nested] 3+ messages in thread

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2021-06-29  9:39 [PATCH bpf-next v2] bpf/devmap: convert remaining READ_ONCE() to rcu_dereference_check() Toke Høiland-Jørgensen
2021-06-30  0:08 ` Martin KaFai Lau
2021-07-01  7:30 ` patchwork-bot+netdevbpf

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