linux-kernel - Re: [PATCH] PCI: use local_pci_probe when best selected cpu is offline

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Date: Wed, 5 Jun 2024 09:41:47 +0800
From: Hongchen Zhang <zhanghongchen@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Huacai Chen
 <chenhuacai@...ngson.cn>, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev,
 stable@...r.kernel.org
Subject: Re: [PATCH] PCI: use local_pci_probe when best selected cpu is
 offline

On 2024/6/4 下午10:57, Huacai Chen wrote:
> Hi, Hongchen,
> 
> On Wed, May 29, 2024 at 7:19 PM Hongchen Zhang
> <zhanghongchen@...ngson.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=1" without "nr_cpus=1" to reproduce it), Therefore,
> in this case, we should call local_pci_probe() instead of work_on_cpu().
> 
OK, Let me modify the log and send V2.
> Huacai
> 
>>
>> Cc: <stable@...r.kernel.org>
>> Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
>> Signed-off-by: Hongchen Zhang <zhanghongchen@...ngson.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, 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
>>
>>


-- 
Best Regards
Hongchen Zhang