From fac30731b9b8a0b7580bf73ddd25035ef0a733a5 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Nov 2022 17:48:29 +0000 Subject: tcp: adopt try_cmpxchg() in tcp_release_cb() try_cmpxchg() is slighly more efficient (at least on x86), and smp_load_acquire(&sk->sk_tsq_flags) could avoid a KCSAN report. Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20221110174829.3403442-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- net/ipv4/tcp_output.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'net/ipv4/tcp_output.c') diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index c69f4d966024..d1cb1ecf8f21 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1077,15 +1077,15 @@ static void tcp_tasklet_func(struct tasklet_struct *t) */ void tcp_release_cb(struct sock *sk) { - unsigned long flags, nflags; + unsigned long flags = smp_load_acquire(&sk->sk_tsq_flags); + unsigned long nflags; /* perform an atomic operation only if at least one flag is set */ do { - flags = sk->sk_tsq_flags; if (!(flags & TCP_DEFERRED_ALL)) return; nflags = flags & ~TCP_DEFERRED_ALL; - } while (cmpxchg(&sk->sk_tsq_flags, flags, nflags) != flags); + } while (!try_cmpxchg(&sk->sk_tsq_flags, &flags, nflags)); if (flags & TCPF_TSQ_DEFERRED) { tcp_tsq_write(sk); -- cgit From b548b17a93fd18357a5a6f535c10c1e68719ad32 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Nov 2022 19:02:39 +0000 Subject: tcp: tcp_wfree() refactoring Use try_cmpxchg() (instead of cmpxchg()) in a more readable way. oval = smp_load_acquire(&sk->sk_tsq_flags); do { ... } while (!try_cmpxchg(&sk->sk_tsq_flags, &oval, nval)); Reduce indentation level. Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20221110190239.3531280-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- net/ipv4/tcp_output.c | 31 ++++++++++++++----------------- 1 file changed, 14 insertions(+), 17 deletions(-) (limited to 'net/ipv4/tcp_output.c') diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index d1cb1ecf8f21..894410dc9293 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1139,6 +1139,8 @@ void tcp_wfree(struct sk_buff *skb) struct sock *sk = skb->sk; struct tcp_sock *tp = tcp_sk(sk); unsigned long flags, nval, oval; + struct tsq_tasklet *tsq; + bool empty; /* Keep one reference on sk_wmem_alloc. * Will be released by sk_free() from here or tcp_tasklet_func() @@ -1155,28 +1157,23 @@ void tcp_wfree(struct sk_buff *skb) if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) goto out; - for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { - struct tsq_tasklet *tsq; - bool empty; - + oval = smp_load_acquire(&sk->sk_tsq_flags); + do { if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) goto out; nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; - nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); - if (nval != oval) - continue; + } while (!try_cmpxchg(&sk->sk_tsq_flags, &oval, nval)); - /* queue this socket to tasklet queue */ - local_irq_save(flags); - tsq = this_cpu_ptr(&tsq_tasklet); - empty = list_empty(&tsq->head); - list_add(&tp->tsq_node, &tsq->head); - if (empty) - tasklet_schedule(&tsq->tasklet); - local_irq_restore(flags); - return; - } + /* queue this socket to tasklet queue */ + local_irq_save(flags); + tsq = this_cpu_ptr(&tsq_tasklet); + empty = list_empty(&tsq->head); + list_add(&tp->tsq_node, &tsq->head); + if (empty) + tasklet_schedule(&tsq->tasklet); + local_irq_restore(flags); + return; out: sk_free(sk); } -- cgit From 459837b522f7dff3b6681f534d8fff4eca19b7d1 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Wed, 23 Nov 2022 17:38:57 +0000 Subject: net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destruction To do that, separate two scenarios: - where it's the first MD5 key on the system, which means that enabling of the static key may need to sleep; - copying of an existing key from a listening socket to the request socket upon receiving a signed TCP segment, where static key was already enabled (when the key was added to the listening socket). Now the life-time of the static branch for TCP-MD5 is until: - last tcp_md5sig_info is destroyed - last socket in time-wait state with MD5 key is closed. Which means that after all sockets with TCP-MD5 keys are gone, the system gets back the performance of disabled md5-key static branch. While at here, provide static_key_fast_inc() helper that does ref counter increment in atomic fashion (without grabbing cpus_read_lock() on CONFIG_JUMP_LABEL=y). This is needed to add a new user for a static_key when the caller controls the lifetime of another user. Signed-off-by: Dmitry Safonov Acked-by: Jakub Kicinski Reviewed-by: Eric Dumazet Signed-off-by: Jakub Kicinski --- net/ipv4/tcp_output.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/ipv4/tcp_output.c') diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 894410dc9293..71d01cf3c13e 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -766,7 +766,7 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, *md5 = NULL; #ifdef CONFIG_TCP_MD5SIG - if (static_branch_unlikely(&tcp_md5_needed) && + if (static_branch_unlikely(&tcp_md5_needed.key) && rcu_access_pointer(tp->md5sig_info)) { *md5 = tp->af_specific->md5_lookup(sk, sk); if (*md5) { @@ -922,7 +922,7 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb *md5 = NULL; #ifdef CONFIG_TCP_MD5SIG - if (static_branch_unlikely(&tcp_md5_needed) && + if (static_branch_unlikely(&tcp_md5_needed.key) && rcu_access_pointer(tp->md5sig_info)) { *md5 = tp->af_specific->md5_lookup(sk, sk); if (*md5) { -- cgit