linux-kernel - Re: [PATCH v3] PCI: pci_call_probe: call local_pci

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Message-ID: <CAAhV-H4TSHqRg0F8xKb32g5CO2aQv=ibL2D_jqn8eUF8+yEZag@mail.gmail.com>
Date: Mon, 22 Jul 2024 10:11:57 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Hongchen Zhang <zhanghongchen@...ngson.cn>
Cc: Markus Elfring <Markus.Elfring@....de>, Bjorn Helgaas <bhelgaas@...gle.com>, 
	Alex Belits <abelits@...vell.com>, "Peter Zijlstra (Intel)" <peterz@...radead.org>, 
	Nitesh Narayan Lal <nitesh@...hat.com>, Frederic Weisbecker <frederic@...nel.org>, linux-pci@...r.kernel.org, 
	linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev, 
	stable@...r.kernel.org, Huacai Chen <chenhuacai@...ngson.cn>
Subject: Re: [PATCH v3] PCI: pci_call_probe: call local_pci_probe() when
 selected cpu is offline

gentle ping?

Huacai

On Thu, Jun 13, 2024 at 3:43 PM Hongchen Zhang
<zhanghongchen@...ngson.cn> wrote:
>
> Call work_on_cpu(cpu, fn, arg) in pci_call_probe() while the argument
> @cpu is a offline cpu would cause system stuck forever.
>
> This can be happen if a node is online while all its CPUs are
> offline (We can use "maxcpus=1" without "nr_cpus=1" to reproduce it).
>
> So, in the above case, let pci_call_probe() call local_pci_probe()
> instead of work_on_cpu() when the best selected cpu is offline.
>
> Fixes: 69a18b18699b ("PCI: Restrict probe functions to housekeeping CPUs")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
> Signed-off-by: Hongchen Zhang <zhanghongchen@...ngson.cn>
> ---
> v2 -> v3: Modify commit message according to Markus's suggestion
> v1 -> v2: Add a method to reproduce the problem
> ---
>  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, struct pci_dev *dev,
>                 free_cpumask_var(wq_domain_mask);
>         }
>
> -       if (cpu < nr_cpu_ids)
> +       if ((cpu < nr_cpu_ids) && cpu_online(cpu))
>                 error = work_on_cpu(cpu, local_pci_probe, &ddi);
>         else
>                 error = local_pci_probe(&ddi);
> --
> 2.33.0
>
>