linux-kernel - [PATCH v2] PCI: use local_pci_probe when best selected cpu is offline

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Date: Wed,  5 Jun 2024 15:54:19 +0800
From: Hongchen Zhang <zhanghongchen@...ngson.cn>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	loongarch@...ts.linux.dev,
	Hongchen Zhang <zhanghongchen@...ngson.cn>,
	stable@...r.kernel.org,
	Huacai Chen <chenhuacai@...ngson.cn>
Subject: [PATCH v2] PCI: use local_pci_probe when best selected cpu is offline

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().

Cc: <stable@...r.kernel.org>
Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
Signed-off-by: Hongchen Zhang <zhanghongchen@...ngson.cn>
---
v1 -> v2 Added the method to reproduce this issue
---
 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