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authorEric Dumazet <edumazet@google.com>2024-05-03 19:20:57 +0000
committerPaolo Abeni <pabeni@redhat.com>2024-05-07 11:14:50 +0200
commit6890ab31d1a35444741e6150db19d64797db2919 (patch)
tree9f0e4ae240841eb23698a9c4e45115929997b525 /net/core
parent6747a5d4990b8c8d7392f7a06b7a4bb5f4ada80e (diff)
rtnetlink: do not depend on RTNL in rtnl_fill_proto_down()
Change dev_change_proto_down() and dev_change_proto_down_reason() to write once on dev->proto_down and dev->proto_down_reason. Then rtnl_fill_proto_down() can use READ_ONCE() annotations and run locklessly. rtnl_proto_down_size() should assume worst case, because readng dev->proto_down_reason multiple times would be racy without RTNL in the future. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Simon Horman <horms@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/dev.c11
-rw-r--r--net/core/rtnetlink.c8
2 files changed, 11 insertions, 8 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index d9d9a0d91593..d2ce91a334c1 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9223,7 +9223,7 @@ int dev_change_proto_down(struct net_device *dev, bool proto_down)
netif_carrier_off(dev);
else
netif_carrier_on(dev);
- dev->proto_down = proto_down;
+ WRITE_ONCE(dev->proto_down, proto_down);
return 0;
}
@@ -9237,18 +9237,21 @@ int dev_change_proto_down(struct net_device *dev, bool proto_down)
void dev_change_proto_down_reason(struct net_device *dev, unsigned long mask,
u32 value)
{
+ u32 proto_down_reason;
int b;
if (!mask) {
- dev->proto_down_reason = value;
+ proto_down_reason = value;
} else {
+ proto_down_reason = dev->proto_down_reason;
for_each_set_bit(b, &mask, 32) {
if (value & (1 << b))
- dev->proto_down_reason |= BIT(b);
+ proto_down_reason |= BIT(b);
else
- dev->proto_down_reason &= ~BIT(b);
+ proto_down_reason &= ~BIT(b);
}
}
+ WRITE_ONCE(dev->proto_down_reason, proto_down_reason);
}
struct bpf_xdp_link {
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 16b5f9c68bbf..dfdd08006fae 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1036,8 +1036,8 @@ static size_t rtnl_proto_down_size(const struct net_device *dev)
{
size_t size = nla_total_size(1);
- if (dev->proto_down_reason)
- size += nla_total_size(0) + nla_total_size(4);
+ /* Assume dev->proto_down_reason is not zero. */
+ size += nla_total_size(0) + nla_total_size(4);
return size;
}
@@ -1737,10 +1737,10 @@ static int rtnl_fill_proto_down(struct sk_buff *skb,
struct nlattr *pr;
u32 preason;
- if (nla_put_u8(skb, IFLA_PROTO_DOWN, dev->proto_down))
+ if (nla_put_u8(skb, IFLA_PROTO_DOWN, READ_ONCE(dev->proto_down)))
goto nla_put_failure;
- preason = dev->proto_down_reason;
+ preason = READ_ONCE(dev->proto_down_reason);
if (!preason)
return 0;