From b548b17a93fd18357a5a6f535c10c1e68719ad32 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Nov 2022 19:02:39 +0000 Subject: [PATCH] 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(-) 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); } -- 2.39.5