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From: Eric Dumazet <edumazet@google.com>
To: shironeko@tesaguri.club, Jose Alonso <joalonsof@gmail.com>
Cc: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	 Paolo Abeni <pabeni@redhat.com>,
	netdev@vger.kernel.org,
	 Soheil Hassas Yeganeh <soheil@google.com>,
	Neal Cardwell <ncardwell@google.com>,
	 Yuchung Cheng <ycheng@google.com>,
	eric.dumazet@gmail.com
Subject: Re: [PATCH net-next] tcp: get rid of sysctl_tcp_adv_win_scale
Date: Tue, 2 Apr 2024 17:50:31 +0200	[thread overview]
Message-ID: <CANn89iKMS2cvgca7qOrVMhWQOoJMuZ-tJ99WTtkXng1O69rOdQ@mail.gmail.com> (raw)
In-Reply-To: <c110f41a0d2776b525930f213ca9715c@tesaguri.club>

On Tue, Apr 2, 2024 at 5:28 PM <shironeko@tesaguri.club> wrote:
>
> Hi all,
>
> These parts seems to be causing a regression for a specific USB NIC, I
> have this on one of home server, and it's network will randomly cut out
> a few times a week.
> Seems others have ran into the same issue with this particular NIC as
> well https://bugzilla.kernel.org/show_bug.cgi?id=218536
>
> > +/* inverse of tcp_win_from_space() */
> > +static inline int tcp_space_from_win(const struct sock *sk, int win)
> > +{
> > +     u64 val = (u64)win << TCP_RMEM_TO_WIN_SCALE;
> > +
> > +     do_div(val, tcp_sk(sk)->scaling_ratio);
> > +     return val;
> > +}
> > +
> > +static inline void tcp_scaling_ratio_init(struct sock *sk)
> > +{
> > +     /* Assume a conservative default of 1200 bytes of payload per 4K
> > page.
> > +      * This may be adjusted later in tcp_measure_rcv_mss().
> > +      */
> > +     tcp_sk(sk)->scaling_ratio = (1200 << TCP_RMEM_TO_WIN_SCALE) /
> > +                                 SKB_TRUESIZE(4096);
> >  }
> ...
> > @@ -740,12 +750,7 @@ void tcp_rcv_space_adjust(struct sock *sk)
> >               do_div(grow, tp->rcvq_space.space);
> >               rcvwin += (grow << 1);
> >
> > -             rcvmem = SKB_TRUESIZE(tp->advmss + MAX_TCP_HEADER);
> > -             while (tcp_win_from_space(sk, rcvmem) < tp->advmss)
> > -                     rcvmem += 128;
> > -
> > -             do_div(rcvwin, tp->advmss);
> > -             rcvbuf = min_t(u64, rcvwin * rcvmem,
> > +             rcvbuf = min_t(u64, tcp_space_from_win(sk, rcvwin),
> >                              READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2]));
> >               if (rcvbuf > sk->sk_rcvbuf) {
> >                       WRITE_ONCE(sk->sk_rcvbuf, rcvbuf);
>
> The NIC:
> usb 2-2: new SuperSpeed USB device number 4 using xhci_hcd
> usb 2-2: New USB device found, idVendor=0b95, idProduct=1790, bcdDevice=
> 1.00
> usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
> usb 2-2: Product: AX88179
> usb 2-2: Manufacturer: ASIX Elec. Corp.
> usb 2-2: SerialNumber: 0000000000009D
> ax88179_178a 2-2:1.0 eth0: register 'ax88179_178a' at
> usb-0000:00:14.0-2, ASIX AX88179 USB 3.0 Gigabit Ethernet,
> 02:5e:c0:4b:a4:f7
> ax88179_178a 2-2:1.0 eth0: ax88179 - Link status is: 1
>
> The dmesg error I get:
>

Thanks for the report. This driver is probably lying on skb->truesize.

This commit looks suspicious

commit f8ebb3ac881b17712e1d5967c97ab1806b16d3d6
Author: Jose Alonso <joalonsof@gmail.com>
Date:   Tue Jun 28 12:13:02 2022 -0300

    net: usb: ax88179_178a: Fix packet receiving

  reply	other threads:[~2024-04-02 15:50 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-17 15:29 [PATCH net-next] tcp: get rid of sysctl_tcp_adv_win_scale Eric Dumazet
2023-07-17 16:52 ` Soheil Hassas Yeganeh
2023-07-17 17:17   ` Eric Dumazet
2023-07-17 17:20     ` Soheil Hassas Yeganeh
2023-07-19  2:10 ` patchwork-bot+netdevbpf
2023-07-20 15:41 ` Paolo Abeni
2023-07-20 15:50   ` Eric Dumazet
2023-11-03  6:10 ` Jiri Slaby
2023-11-03  6:56   ` Jiri Slaby
2023-11-03  7:07     ` Jiri Slaby
2023-11-03  8:17       ` Eric Dumazet
2023-11-03  9:27         ` Michal Kubecek
2023-11-03  9:53           ` Eric Dumazet
2023-11-03 10:14         ` Jiri Slaby
2023-11-03 10:27           ` Eric Dumazet
2023-11-03 11:07             ` Jiri Slaby
2024-04-02 15:28 ` shironeko
2024-04-02 15:50   ` Eric Dumazet [this message]
2024-04-02 16:23     ` Eric Dumazet
2024-04-02 16:29       ` shironeko
2024-04-06  0:22         ` shironeko
2024-04-06  6:11           ` Eric Dumazet
2024-04-06  7:07             ` Eric Dumazet

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