netdev - Re: [PATCH] net: Fixup virtnet_set_affinity() cause cpumask warning

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Date:   Thu, 13 Oct 2022 11:12:52 -0700
From:   Yury Norov <yury.norov@...il.com>
To:     guoren@...nel.org
Cc:     andriy.shevchenko@...ux.intel.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        linux@...musvillemoes.dk, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH] net: Fixup virtnet_set_affinity() cause cpumask warning

On Thu, Oct 13, 2022 at 10:14 AM <guoren@...nel.org> wrote:
>
> From: Guo Ren <guoren@...ux.alibaba.com>
>
> Don't pass nr_bits-1 as arg1 for cpumask_next_wrap, which would
> cause warning now.
>
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at include/linux/cpumask.h:110 cpumask_next_wrap+0x5c/0x80
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.0.0-11659-ge7e38f6cce55-dirty #328
> Hardware name: riscv-virtio,qemu (DT)
> epc : cpumask_next_wrap+0x5c/0x80
>  ra : virtnet_set_affinity+0x1ba/0x1fc
> epc : ffffffff808992ca ra : ffffffff805d84ca sp : ff60000002327a50
>  gp : ffffffff81602390 tp : ff600000023a0000 t0 : 5f74656e74726976
>  t1 : 0000000000000000 t2 : 735f74656e747269 s0 : ff60000002327a90
>  s1 : 0000000000000003 a0 : 0000000000000003 a1 : ffffffff816051c0
>  a2 : 0000000000000004 a3 : 0000000000000000 a4 : 0000000000000000
>  a5 : 0000000000000004 a6 : 0000000000000000 a7 : 0000000000000000
>  s2 : 0000000000000000 s3 : ffffffff816051c0 s4 : ffffffff8160224c
>  s5 : 0000000000000004 s6 : 0000000000000004 s7 : 0000000000000000
>  s8 : 0000000000000003 s9 : ffffffff810aa398 s10: ffffffff80e97d20
>  s11: 0000000000000004 t3 : ffffffff819acc97 t4 : ffffffff819acc97
>  t5 : ffffffff819acc98 t6 : ff60000002327878
> status: 0000000200000120 badaddr: 0000000000000000 cause: 0000000000000003
> [<ffffffff805d84ca>] virtnet_set_affinity+0x1ba/0x1fc
> [<ffffffff805da7ac>] virtnet_probe+0x832/0xf1e
> [<ffffffff804fe61c>] virtio_dev_probe+0x164/0x2de
> [<ffffffff8054c4c4>] really_probe+0x82/0x224
> [<ffffffff8054c6c0>] __driver_probe_device+0x5a/0xaa
> [<ffffffff8054c73c>] driver_probe_device+0x2c/0xb8
> [<ffffffff8054cd66>] __driver_attach+0x76/0x108
> [<ffffffff8054a482>] bus_for_each_dev+0x52/0x9a
> [<ffffffff8054be8c>] driver_attach+0x1a/0x28
> [<ffffffff8054b996>] bus_add_driver+0x154/0x1c2
> [<ffffffff8054d592>] driver_register+0x52/0x108
> [<ffffffff804fe120>] register_virtio_driver+0x1c/0x2c
> [<ffffffff80a29142>] virtio_net_driver_init+0x7a/0xb0
> [<ffffffff80002854>] do_one_initcall+0x66/0x2e4
> [<ffffffff80a01222>] kernel_init_freeable+0x28a/0x304
> [<ffffffff808cb1be>] kernel_init+0x1e/0x110
> [<ffffffff80003c4e>] ret_from_exception+0x0/0x10
> ---[ end trace 0000000000000000 ]---
>
> Fixes: 78e5a3399421 ("cpumask: fix checking valid cpu range")

Please stop saying you're fixing my patch. It reveals the problem, not
creates it.

I have a deep rework for cpumask_next_wrap(). Will send v2 soon and CC you.

Thanks,
Yury

> Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@...nel.org>
> ---
>  drivers/net/virtio_net.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7106932c6f88..e4b56523b2b5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2300,6 +2300,8 @@ static void virtnet_set_affinity(struct virtnet_info *vi)
>
>                 for (j = 0; j < group_size; j++) {
>                         cpumask_set_cpu(cpu, mask);
> +                       if (cpu == (nr_cpu_ids - 1))
> +                               break;
>                         cpu = cpumask_next_wrap(cpu, cpu_online_mask,
>                                                 nr_cpu_ids, false);
>                 }
> --
> 2.36.1
>