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tcp: tcp_wfree() refactoring

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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 <edumazet@google.com>
Link: https://lore.kernel.org/r/20221110190239.3531280-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet
2022-11-10 19:02:39 +00:00
committed by Jakub Kicinski
parent fac30731b9
commit b548b17a93
1 changed files with 14 additions and 17 deletions
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31
net/ipv4/tcp_output.c
View File

@ -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);
}