netdev - Re: [PATCH net-next 4/7] ipv4: remove get

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Message-ID: <67a55afb822cc_25109e294cc@willemb.c.googlers.com.notmuch>
Date: Thu, 06 Feb 2025 19:59:39 -0500
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>, 
 netdev@...r.kernel.org
Cc: davem@...emloft.net, 
 kuba@...nel.org, 
 edumazet@...gle.com, 
 pabeni@...hat.com, 
 Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next 4/7] ipv4: remove get_rttos

Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@...gle.com>
> 
> Initialize the ip cookie tos field when initializing the cookie, in
> ipcm_init_sk.
> 
> The existing code inverts the standard pattern for initializing cookie
> fields. Default is to initialize the field from the sk, then possibly
> overwrite that when parsing cmsgs (the unlikely case).
> 
> This field inverts that, setting the field to an illegal value and
> after cmsg parsing checking whether the value is still illegal and
> thus should be overridden.
> 
> Be careful to always apply mask INET_DSCP_MASK, as before.
> 
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>
> ---
>  include/net/ip.h       | 11 +++--------
>  net/ipv4/ip_sockglue.c |  4 ++--
>  net/ipv4/ping.c        |  1 -
>  net/ipv4/raw.c         |  1 -
>  net/ipv4/udp.c         |  1 -
>  5 files changed, 5 insertions(+), 13 deletions(-)
> 
> diff --git a/include/net/ip.h b/include/net/ip.h
> index 6af16545b3e3..6819704e2642 100644
> --- a/include/net/ip.h
> +++ b/include/net/ip.h
> @@ -92,7 +92,9 @@ static inline void ipcm_init(struct ipcm_cookie *ipcm)
>  static inline void ipcm_init_sk(struct ipcm_cookie *ipcm,
>  				const struct inet_sock *inet)
>  {
> -	ipcm_init(ipcm);
> +	*ipcm = (struct ipcm_cookie) {
> +		.tos = READ_ONCE(inet->tos) & INET_DSCP_MASK,
> +	};
>  
>  	sockcm_init(&ipcm->sockc, &inet->sk);
>  
> @@ -256,13 +258,6 @@ static inline u8 ip_sendmsg_scope(const struct inet_sock *inet,
>  	return RT_SCOPE_UNIVERSE;
>  }
>  
> -static inline __u8 get_rttos(struct ipcm_cookie* ipc, struct inet_sock *inet)
> -{
> -	u8 dsfield = ipc->tos != -1 ? ipc->tos : READ_ONCE(inet->tos);
> -
> -	return dsfield & INET_DSCP_MASK;
> -}
> -
>  /* datagram.c */
>  int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
>  int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index 6d9c5c20b1c4..98b1e4a8b72e 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -314,8 +314,8 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc,
>  				return -EINVAL;
>  			if (val < 0 || val > 255)
>  				return -EINVAL;
> -			ipc->tos = val;
> -			ipc->sockc.priority = rt_tos2priority(ipc->tos);
> +			ipc->sockc.priority = rt_tos2priority(val);
> +			ipc->tos = val & INET_DSCP_MASK;
>  			break;
>  		case IP_PROTOCOL:
>  			if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)))
> diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
> index 619ddc087957..0215885c6df5 100644
> --- a/net/ipv4/ping.c
> +++ b/net/ipv4/ping.c
> @@ -768,7 +768,6 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>  		}
>  		faddr = ipc.opt->opt.faddr;
>  	}
> -	tos = get_rttos(&ipc, inet);

Here and elsewhere, subsequent code needs to use ipc.tos directly.