linux-kernel - [PATCH] PCI: vmd: guard device addition and removal

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Message-Id: <20230313173733.1815277-1-vicamo.yang@canonical.com>
Date:   Tue, 14 Mar 2023 01:37:33 +0800
From:   "You-Sheng Yang (vicamo)" <vicamo.yang@...onical.com>
To:     Nirmal Patel <nirmal.patel@...ux.intel.com>,
        Jonathan Derrick <jonathan.derrick@...ux.dev>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Keith Busch <kbusch@...nel.org>
Cc:     "You-Sheng Yang (vicamo)" <vicamo.yang@...onical.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] PCI: vmd: guard device addition and removal

VMD may fail to create sysfs entries while `pci_rescan_bus()` called in
some other drivers like t7xx wwan driver:

  sysfs: cannot create duplicate filename '/devices/.../resource0'
  Call Trace:
   <TASK>
   sysfs_warn_dup.cold+0x17/0x34
   sysfs_add_bin_file_mode_ns+0xc0/0xf0
   sysfs_create_bin_file+0x6d/0xb0
   pci_create_attr+0x117/0x260
   pci_create_resource_files+0x6b/0x150
   pci_create_sysfs_dev_files+0x18/0x30
   pci_bus_add_device+0x30/0x80
   pci_bus_add_devices+0x31/0x80
   pci_bus_add_devices+0x5b/0x80
   vmd_enable_domain.constprop.0+0x6b7/0x880 [vmd]
   vmd_probe+0x16d/0x193 [vmd]

Fixes: 185a383ada2e ("x86/PCI: Add driver for Intel Volume Management Device (VMD)")
Signed-off-by: You-Sheng Yang (vicamo) <vicamo.yang@...onical.com>
---
 drivers/pci/controller/vmd.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 769eedeb8802..f050991bd1e9 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -838,9 +838,13 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	pci_add_resource_offset(&resources, &vmd->resources[1], offset[0]);
 	pci_add_resource_offset(&resources, &vmd->resources[2], offset[1]);
 
+	pci_lock_rescan_remove();
+
 	vmd->bus = pci_create_root_bus(&vmd->dev->dev, vmd->busn_start,
 				       &vmd_ops, sd, &resources);
 	if (!vmd->bus) {
+		pci_unlock_rescan_remove();
+
 		pci_free_resource_list(&resources);
 		vmd_remove_irq_domain(vmd);
 		return -ENODEV;
@@ -893,6 +897,8 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 
 	vmd_acpi_end();
 
+	pci_unlock_rescan_remove();
+
 	WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj,
 			       "domain"), "Can't create symlink to domain\n");
 	return 0;
-- 
2.39.2