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

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Message-ID: <49907fd5-3069-dc19-1388-590e08600037@linux.intel.com>
Date:   Wed, 15 Mar 2023 07:39:03 -0700
From:   "Patel, Nirmal" <nirmal.patel@...ux.intel.com>
To:     "You-Sheng Yang (vicamo)" <vicamo.yang@...onical.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:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: vmd: guard device addition and removal

On 3/13/2023 10:37 AM, You-Sheng Yang (vicamo) wrote:
> 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;

Reviewed-by: Nirmal Patel <nirmal.patel@...ux.intel.com>

Thanks