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udp: relax atomic operation on sk->sk_rmem_alloc

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atomic_add_return() is more expensive than atomic_add()
and seems overkill in UDP rx fast path.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240328144032.1864988-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-03-28 14:40:30 +00:00 committed by Jakub Kicinski
parent 6055796995
commit 6a1f12dd85
1 changed files with 1 additions and 6 deletions
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7
net/ipv4/udp.c
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@ -1516,12 +1516,7 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
size = skb->truesize; size = skb->truesize;
udp_set_dev_scratch(skb); udp_set_dev_scratch(skb);
/* we drop only if the receive buf is full and the receive atomic_add(size, &sk->sk_rmem_alloc);
* queue contains some other skb
*/
rmem = atomic_add_return(size, &sk->sk_rmem_alloc);
if (rmem > (size + (unsigned int)sk->sk_rcvbuf))
goto uncharge_drop;
spin_lock(&list->lock); spin_lock(&list->lock);
err = udp_rmem_schedule(sk, size); err = udp_rmem_schedule(sk, size);