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Message-ID: <ZMpPjAaRzSRy-Vo_@TONYMAC-ALIBABA.local>
Date: Wed, 2 Aug 2023 20:43:56 +0800
From: Tony Lu <tonylu@...ux.alibaba.com>
To: Gerd Bayer <gbayer@...ux.ibm.com>
Cc: Wenjia Zhang <wenjia@...ux.ibm.com>,
Jan Karcher <jaka@...ux.ibm.com>,
Paolo Abeni <pabeni@...hat.com>,
Karsten Graul <kgraul@...ux.ibm.com>,
"D . Wythe" <alibuda@...ux.alibaba.com>,
Wen Gu <guwen@...ux.alibaba.com>,
"David S . Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, linux-s390@...r.kernel.org,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 2/2] net/smc: Use correct buffer sizes when switching
between TCP and SMC
On Wed, Aug 02, 2023 at 11:33:13AM +0200, Gerd Bayer wrote:
> Tuning of the effective buffer size through setsockopts was working for
> SMC traffic only but not for TCP fall-back connections even before
> commit 0227f058aa29 ("net/smc: Unbind r/w buffer size from clcsock and
> make them tunable"). That change made it apparent that TCP fall-back
> connections would use net.smc.[rw]mem as buffer size instead of
> net.ipv4_tcp_[rw]mem.
>
> Amend the code that copies attributes between the (TCP) clcsock and the
> SMC socket and adjust buffer sizes appropriately:
> - Copy over sk_userlocks so that both sockets agree on whether tuning
> via setsockopt is active.
> - When falling back to TCP use sk_sndbuf or sk_rcvbuf as specified with
> setsockopt. Otherwise, use the sysctl value for TCP/IPv4.
> - Likewise, use either values from setsockopt or from sysctl for SMC
> (duplicated) on successful SMC connect.
>
> In smc_tcp_listen_work() drop the explicit copy of buffer sizes as that
> is taken care of by the attribute copy.
>
> Fixes: 0227f058aa29 ("net/smc: Unbind r/w buffer size from clcsock and make them tunable")
> Signed-off-by: Gerd Bayer <gbayer@...ux.ibm.com>
> Reviewed-by: Wenjia Zhang <wenjia@...ux.ibm.com>
> Reviewed-by: Jan Karcher <jaka@...ux.ibm.com>
Reviewed-by: Tony Lu <tonylu@...ux.alibaba.com>
>
^^^^ nit: a extra new line here.
> ---
> net/smc/af_smc.c | 76 ++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 54 insertions(+), 22 deletions(-)
>
> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
> index 1fcf1e42474a..1c8ed19041d7 100644
> --- a/net/smc/af_smc.c
> +++ b/net/smc/af_smc.c
> @@ -436,13 +436,63 @@ static int smc_bind(struct socket *sock, struct sockaddr *uaddr,
> return rc;
> }
>
> +/* copy only relevant settings and flags of SOL_SOCKET level from smc to
> + * clc socket (since smc is not called for these options from net/core)
> + */
> +
> +#define SK_FLAGS_SMC_TO_CLC ((1UL << SOCK_URGINLINE) | \
> + (1UL << SOCK_KEEPOPEN) | \
> + (1UL << SOCK_LINGER) | \
> + (1UL << SOCK_BROADCAST) | \
> + (1UL << SOCK_TIMESTAMP) | \
> + (1UL << SOCK_DBG) | \
> + (1UL << SOCK_RCVTSTAMP) | \
> + (1UL << SOCK_RCVTSTAMPNS) | \
> + (1UL << SOCK_LOCALROUTE) | \
> + (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE) | \
> + (1UL << SOCK_RXQ_OVFL) | \
> + (1UL << SOCK_WIFI_STATUS) | \
> + (1UL << SOCK_NOFCS) | \
> + (1UL << SOCK_FILTER_LOCKED) | \
> + (1UL << SOCK_TSTAMP_NEW))
> +
> +/* if set, use value set by setsockopt() - else use IPv4 or SMC sysctl value */
> +static void smc_adjust_sock_bufsizes(struct sock *nsk, struct sock *osk,
> + unsigned long mask)
> +{
> + struct net *nnet;
> +
> + nnet = nsk->sk_net.net;
Better to combine these two lines with existed helper.
struct net *net = sock_net(nsk);
> +
> + nsk->sk_userlocks = osk->sk_userlocks;
> +
> + if (osk->sk_userlocks & SOCK_SNDBUF_LOCK) {
> + nsk->sk_sndbuf = osk->sk_sndbuf;
> + } else {
> + if (mask == SK_FLAGS_SMC_TO_CLC)
> + WRITE_ONCE(nsk->sk_sndbuf,
> + READ_ONCE(nnet->ipv4.sysctl_tcp_wmem[1]));
> + else
> + WRITE_ONCE(nsk->sk_sndbuf,
> + 2 * READ_ONCE(nnet->smc.sysctl_wmem));
> + }
> + if (osk->sk_userlocks & SOCK_RCVBUF_LOCK) {
> + nsk->sk_rcvbuf = osk->sk_rcvbuf;
> + } else {
> + if (mask == SK_FLAGS_SMC_TO_CLC)
> + WRITE_ONCE(nsk->sk_rcvbuf,
> + READ_ONCE(nnet->ipv4.sysctl_tcp_rmem[1]));
> + else
> + WRITE_ONCE(nsk->sk_rcvbuf,
> + 2 * READ_ONCE(nnet->smc.sysctl_rmem));
> + }
> +}
> +
> static void smc_copy_sock_settings(struct sock *nsk, struct sock *osk,
> unsigned long mask)
> {
> /* options we don't get control via setsockopt for */
> nsk->sk_type = osk->sk_type;
> - nsk->sk_sndbuf = osk->sk_sndbuf;
> - nsk->sk_rcvbuf = osk->sk_rcvbuf;
> nsk->sk_sndtimeo = osk->sk_sndtimeo;
> nsk->sk_rcvtimeo = osk->sk_rcvtimeo;
> nsk->sk_mark = osk->sk_mark;
> @@ -453,26 +503,10 @@ static void smc_copy_sock_settings(struct sock *nsk, struct sock *osk,
>
> nsk->sk_flags &= ~mask;
> nsk->sk_flags |= osk->sk_flags & mask;
> +
> + smc_adjust_sock_bufsizes(nsk, osk, mask);
> }
>
> -#define SK_FLAGS_SMC_TO_CLC ((1UL << SOCK_URGINLINE) | \
> - (1UL << SOCK_KEEPOPEN) | \
> - (1UL << SOCK_LINGER) | \
> - (1UL << SOCK_BROADCAST) | \
> - (1UL << SOCK_TIMESTAMP) | \
> - (1UL << SOCK_DBG) | \
> - (1UL << SOCK_RCVTSTAMP) | \
> - (1UL << SOCK_RCVTSTAMPNS) | \
> - (1UL << SOCK_LOCALROUTE) | \
> - (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE) | \
> - (1UL << SOCK_RXQ_OVFL) | \
> - (1UL << SOCK_WIFI_STATUS) | \
> - (1UL << SOCK_NOFCS) | \
> - (1UL << SOCK_FILTER_LOCKED) | \
> - (1UL << SOCK_TSTAMP_NEW))
> -/* copy only relevant settings and flags of SOL_SOCKET level from smc to
> - * clc socket (since smc is not called for these options from net/core)
> - */
> static void smc_copy_sock_settings_to_clc(struct smc_sock *smc)
> {
> smc_copy_sock_settings(smc->clcsock->sk, &smc->sk, SK_FLAGS_SMC_TO_CLC);
> @@ -2479,8 +2513,6 @@ static void smc_tcp_listen_work(struct work_struct *work)
> sock_hold(lsk); /* sock_put in smc_listen_work */
> INIT_WORK(&new_smc->smc_listen_work, smc_listen_work);
> smc_copy_sock_settings_to_smc(new_smc);
> - new_smc->sk.sk_sndbuf = lsmc->sk.sk_sndbuf;
> - new_smc->sk.sk_rcvbuf = lsmc->sk.sk_rcvbuf;
> sock_hold(&new_smc->sk); /* sock_put in passive closing */
> if (!queue_work(smc_hs_wq, &new_smc->smc_listen_work))
> sock_put(&new_smc->sk);
> --
> 2.41.0
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