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[34.145.139.141]) by smtp.gmail.com with UTF8SMTPSA id 6a1803df08f44-77f44157463sm62195476d6.2.2025.09.17.08.01.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Sep 2025 08:01:30 -0700 (PDT) Date: Wed, 17 Sep 2025 11:01:30 -0400 From: Willem de Bruijn To: Eric Dumazet , "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Willem de Bruijn , Kuniyuki Iwashima , David Ahern , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet Message-ID: In-Reply-To: <20250916160951.541279-7-edumazet@google.com> References: <20250916160951.541279-1-edumazet@google.com> <20250916160951.541279-7-edumazet@google.com> Subject: Re: [PATCH net-next 06/10] udp: update sk_rmem_alloc before busylock acquisition Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Eric Dumazet wrote: > Avoid piling too many producers on the busylock > by updating sk_rmem_alloc before busylock acquisition. > > Signed-off-by: Eric Dumazet > --- > net/ipv4/udp.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c > index edd846fee90ff7850356a5cb3400ce96856e5429..658ae87827991a78c25c2172d52e772c94ea217f 100644 > --- a/net/ipv4/udp.c > +++ b/net/ipv4/udp.c > @@ -1753,13 +1753,16 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb) > if (rmem > (rcvbuf >> 1)) { > skb_condense(skb); > size = skb->truesize; > + rmem = atomic_add_return(size, &sk->sk_rmem_alloc); > + if (rmem > rcvbuf) > + goto uncharge_drop; This does more than just reorganize code. Can you share some context on the behavioral change? > busy = busylock_acquire(sk); > + } else { > + atomic_add(size, &sk->sk_rmem_alloc); > } > > udp_set_dev_scratch(skb); > > - atomic_add(size, &sk->sk_rmem_alloc); > - > spin_lock(&list->lock); > err = udp_rmem_schedule(sk, size); > if (err) { > -- > 2.51.0.384.g4c02a37b29-goog >