linux-kernel - [PATCH] PCI: Fix pci devices double register WARN in the kernel starting process

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Message-Id: <20250702155112.40124-2-heshuan@bytedance.com>
Date: Wed,  2 Jul 2025 23:51:12 +0800
From: Shuan He <heshuan@...edance.com>
To: bhelgaas@...gle.com,
	cuiyunhui@...edance.com
Cc: linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	heshuan@...edance.com,
	sunilvl@...tanamicro.com
Subject: [PATCH] PCI: Fix pci devices double register WARN in the kernel starting process

To avoid the double register of pcie device (otherwise a WARNING will
be triggered), two more steps are added in the pci_proc_init function.
1. The pci_rescan_remove_lock is held to prevent the concurrent issue
with pci_bus_add_devices.
2. The PCI_DEV_ADDED bit is added to dev->priv_flags after the device is
successfully registered to procfs.

WARN Trace:
[    0.518993] proc_dir_entry '000c:00/00.0' already registered
[    0.519187] WARNING: CPU: 2 PID: 179 at fs/proc/generic.c:375 proc_register+0xf6/0x180
[    0.519214] [<ffffffff804055a6>] proc_register+0xf6/0x180
[    0.519217] [<ffffffff80405a9e>] proc_create_data+0x3e/0x60
[    0.519220] [<ffffffff80616e44>] pci_proc_attach_device+0x74/0x130
[    0.509991] [<ffffffff805f1af2>] pci_bus_add_device+0x42/0x100
[    0.509997] [<ffffffff805f1c76>] pci_bus_add_devices+0xc6/0x110
[    0.519230] [<ffffffff8066763c>] acpi_pci_root_add+0x54c/0x810
[    0.519233] [<ffffffff8065d206>] acpi_bus_attach+0x196/0x2f0
[    0.519234] [<ffffffff8065d390>] acpi_scan_clear_dep_fn+0x30/0x70
[    0.519236] [<ffffffff800468fa>] process_one_work+0x19a/0x390
[    0.519239] [<ffffffff80047a6e>] worker_thread+0x2be/0x420
[    0.519241] [<ffffffff80050dc4>] kthread+0xc4/0xf0
[    0.519243] [<ffffffff80ad6ad2>] ret_from_fork+0xe/0x1c

Signed-off-by: Shuan He <heshuan@...edance.com>
---
 drivers/pci/proc.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index 9348a0fb8084..6506316c8a31 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -468,9 +468,14 @@ static int __init pci_proc_init(void)
 	proc_create_seq("devices", 0, proc_bus_pci_dir,
 		    &proc_bus_pci_devices_op);
 	proc_initialized = 1;
-	for_each_pci_dev(dev)
-		pci_proc_attach_device(dev);
-
+	pci_lock_rescan_remove();
+	for_each_pci_dev(dev) {
+		if (pci_dev_is_added(dev))
+			continue;
+		if (!pci_proc_attach_device(dev))
+			pci_dev_assign_added(dev, true);
+	}
+	pci_unlock_rescan_remove();
 	return 0;
 }
 device_initcall(pci_proc_init);
-- 
2.39.5 (Apple Git-154)