netdev - RE: [PATCH v2 net] udp: fix busy polling

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Message-ID: <f3404710d9ab4692aa33501514122604@AcuMS.aculab.com>
Date: Fri, 19 Jan 2024 22:45:45 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Eric Dumazet' <edumazet@...gle.com>, "David S . Miller"
	<davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>
CC: Willem de Bruijn <willemb@...gle.com>, David Ahern <dsahern@...nel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>, "eric.dumazet@...il.com"
	<eric.dumazet@...il.com>
Subject: RE: [PATCH v2 net] udp: fix busy polling

...
> +static inline bool sk_is_inet(const struct sock *sk)
> +{
> +	int family = READ_ONCE(sk->sk_family);
> +
> +	return family == AF_INET || family == AF_INET6;
> +}
> +
>  static inline bool sk_is_tcp(const struct sock *sk)
>  {
> -	return sk->sk_type == SOCK_STREAM && sk->sk_protocol == IPPROTO_TCP;
> +	return sk_is_inet(sk) &&
> +	       sk->sk_type == SOCK_STREAM &&
> +	       sk->sk_protocol == IPPROTO_TCP;
> +}
> +
> +static inline bool sk_is_udp(const struct sock *sk)
> +{
> +	return sk_is_inet(sk) &&
> +	       sk->sk_type == SOCK_DGRAM &&
> +	       sk->sk_protocol == IPPROTO_UDP;
>  }

Do you need to check sk_type as well as sk_protocol?
I'd have thought it was enough to check sk_protocol
and then sk_family ?
Certainly testing sk_protocol first will generate 'false'
quickest.

	David

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