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From: Huacai Chen <chenhuacai@kernel.org>
Date: Tue, 4 Jun 2024 22:57:06 +0800
Message-ID: <CAAhV-H5KD8BPzZYjpj5s4iSjOfJr+Q9hCV1nQn6fsUXPU8sriA@mail.gmail.com>
Subject: Re: [PATCH] PCI: use local_pci_probe when best selected cpu is offline
To: Hongchen Zhang <zhanghongchen@loongson.cn>
Cc: Bjorn Helgaas <bhelgaas@google.com>, Huacai Chen <chenhuacai@loongson.cn>, 
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, 
	loongarch@lists.linux.dev, stable@vger.kernel.org
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Hi, Hongchen,

On Wed, May 29, 2024 at 7:19=E2=80=AFPM Hongchen Zhang
<zhanghongchen@loongson.cn> wrote:
The title should be better like this:
PCI: Use local_pci_probe() when best selected CPU is offline

>
> When the best selected cpu is offline, work_on_cpu will stuck
> forever. Therefore, in this case, we should call
> local_pci_probe instead of work_on_cpu.

It is better to reword like this:

When the best selected CPU is offline, work_on_cpu() will stuck forever.
This can be happen if a node is online while all its CPUs are offline
(we can use "maxcpus=3D1" without "nr_cpus=3D1" to reproduce it), Therefore=
,
in this case, we should call local_pci_probe() instead of work_on_cpu().

Huacai

>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> Signed-off-by: Hongchen Zhang <zhanghongchen@loongson.cn>
> ---
>  drivers/pci/pci-driver.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index af2996d0d17f..32a99828e6a3 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -386,7 +386,7 @@ static int pci_call_probe(struct pci_driver *drv, str=
uct pci_dev *dev,
>                 free_cpumask_var(wq_domain_mask);
>         }
>
> -       if (cpu < nr_cpu_ids)
> +       if ((cpu < nr_cpu_ids) && cpu_online(cpu))
>                 error =3D work_on_cpu(cpu, local_pci_probe, &ddi);
>         else
>                 error =3D local_pci_probe(&ddi);
> --
> 2.33.0
>
>