netdev - [PATCH bpf-next v4 5/6] net: core: Allow netdev_lower_get_next_private

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Message-Id: <20210728234350.28796-6-joamaki@gmail.com>
Date:   Wed, 28 Jul 2021 23:43:49 +0000
From:   joamaki@...il.com
To:     bpf@...r.kernel.org
Cc:     netdev@...r.kernel.org, daniel@...earbox.net, j.vosburgh@...il.com,
        andy@...yhouse.net, vfalico@...il.com, andrii@...nel.org,
        maciej.fijalkowski@...el.com, magnus.karlsson@...el.com,
        Jussi Maki <joamaki@...il.com>
Subject: [PATCH bpf-next v4 5/6] net: core: Allow netdev_lower_get_next_private_rcu in bh context

From: Jussi Maki <joamaki@...il.com>

For the XDP bonding slave lookup to work in the NAPI poll context
in which the redudant rcu_read_lock() has been removed we have to
follow the same approach as in [1] and modify the WARN_ON to also
check rcu_read_lock_bh_held().

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=694cea395fded425008e93cd90cfdf7a451674af

Signed-off-by: Jussi Maki <joamaki@...il.com>
---
 net/core/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 99cb14242164..9cdb551db5dd 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7588,7 +7588,7 @@ void *netdev_lower_get_next_private_rcu(struct net_device *dev,
 {
 	struct netdev_adjacent *lower;
 
-	WARN_ON_ONCE(!rcu_read_lock_held());
+	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
 
 	lower = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
 
-- 
2.17.1