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| author | Eric Dumazet <edumazet@google.com> | 2023-11-30 18:41:35 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-12-01 19:31:10 -0800 |
| commit | b32e8fbeace6117b00b072eef3f1726149fe0298 (patch) | |
| tree | 98bce6b2b40be12f5d5ff05a70b944ca436761b1 /net | |
| parent | 527d2cd8b852e06c25c129fe400832bf88d2b5b0 (diff) | |
| download | linux-b32e8fbeace6117b00b072eef3f1726149fe0298.tar.gz linux-b32e8fbeace6117b00b072eef3f1726149fe0298.tar.bz2 linux-b32e8fbeace6117b00b072eef3f1726149fe0298.zip | |
tcp: tcp_gro_dev_warn() cleanup
Use DO_ONCE_LITE_IF() and __cold attribute to put tcp_gro_dev_warn()
out of line.
This also allows the message to be printed again after a
"echo 1 > /sys/kernel/debug/clear_warn_once"
Also add a READ_ONCE() when reading device mtu, as it could
be changed concurrently.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231130184135.4130860-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_input.c | 29 |
1 files changed, 11 insertions, 18 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index bcb55d98004c..0548f0c12155 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -202,23 +202,17 @@ static void bpf_skops_established(struct sock *sk, int bpf_op, } #endif -static void tcp_gro_dev_warn(struct sock *sk, const struct sk_buff *skb, - unsigned int len) +static __cold void tcp_gro_dev_warn(const struct sock *sk, const struct sk_buff *skb, + unsigned int len) { - static bool __once __read_mostly; + struct net_device *dev; - if (!__once) { - struct net_device *dev; - - __once = true; - - rcu_read_lock(); - dev = dev_get_by_index_rcu(sock_net(sk), skb->skb_iif); - if (!dev || len >= dev->mtu) - pr_warn("%s: Driver has suspect GRO implementation, TCP performance may be compromised.\n", - dev ? dev->name : "Unknown driver"); - rcu_read_unlock(); - } + rcu_read_lock(); + dev = dev_get_by_index_rcu(sock_net(sk), skb->skb_iif); + if (!dev || len >= READ_ONCE(dev->mtu)) + pr_warn("%s: Driver has suspect GRO implementation, TCP performance may be compromised.\n", + dev ? dev->name : "Unknown driver"); + rcu_read_unlock(); } /* Adapt the MSS value used to make delayed ack decision to the @@ -250,9 +244,8 @@ static void tcp_measure_rcv_mss(struct sock *sk, const struct sk_buff *skb) icsk->icsk_ack.rcv_mss = min_t(unsigned int, len, tcp_sk(sk)->advmss); /* Account for possibly-removed options */ - if (unlikely(len > icsk->icsk_ack.rcv_mss + - MAX_TCP_OPTION_SPACE)) - tcp_gro_dev_warn(sk, skb, len); + DO_ONCE_LITE_IF(len > icsk->icsk_ack.rcv_mss + MAX_TCP_OPTION_SPACE, + tcp_gro_dev_warn, sk, skb, len); /* If the skb has a len of exactly 1*MSS and has the PSH bit * set then it is likely the end of an application write. So * more data may not be arriving soon, and yet the data sender |