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From: Hongchen Zhang <zhanghongchen@loongson.cn>
To: Markus Elfring <Markus.Elfring@web.de>,
	Bjorn Helgaas <bhelgaas@google.com>
Cc: Alex Belits <abelits@marvell.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Nitesh Narayan Lal <nitesh@redhat.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	loongarch@lists.linux.dev,
	Hongchen Zhang <zhanghongchen@loongson.cn>,
	stable@vger.kernel.org,
	Huacai Chen <chenhuacai@loongson.cn>
Subject: [PATCH v3] PCI: pci_call_probe: call local_pci_probe() when selected cpu is offline
Date: Thu, 13 Jun 2024 15:42:58 +0800
Message-Id: <20240613074258.4124603-1-zhanghongchen@loongson.cn>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

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@vger.kernel.org>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Hongchen Zhang <zhanghongchen@loongson.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