Re: [PATCH v2] x86/amd/node: Release reserved config regions on init error

[Mario Limonciello <mario.limonciello@amd.com>]

On 9/15/26 12:23, yolezz wrote:
> In amd_smn_init(), if pci_request_config_region_exclusive() fails or
> if kzalloc_objs() fails to allocate memory for amd_roots, the already
> reserved PCI config regions are left allocated.
> 
> Use a __free() cleanup helper to automatically release all reserved PCI
> config space regions on error exit paths.
> 
> Fixes: 83518453074d ("x86/amd_node: Add SMN offsets to exclusive region access")
> Signed-off-by: yolezz <yolezz.secret@gmail.com>
> ---
> v2:
>   - Use a __free() cleanup helper instead of manual error rollback, as suggested by Mario.
> 
>   arch/x86/kernel/amd_node.c | 23 ++++++++++++++++-------
>   1 file changed, 16 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
> index 6a96d888b5a7..20451f0ad8c7 100644
> --- a/arch/x86/kernel/amd_node.c
> +++ b/arch/x86/kernel/amd_node.c
> @@ -239,15 +239,22 @@ static struct pci_dev *get_next_root(struct pci_dev *root)
>   	return root;
>   }
>   
> -static void amd_smn_release_config_regions(u16 num_roots)
> +static void amd_smn_release_config_regions(u16 *num_roots)
>   {
>   	struct pci_dev *root __free(pci_dev_put) = NULL;
>   
> -	/* Release the PCI config space for each root device. */
> -	while (num_roots-- && (root = get_next_root(root)))
> +	if (!num_roots)
> +		return;
> +
> +	while (*num_roots && (root = get_next_root(root))) {
>   		pci_release_config_region(root, 0, PCI_CFG_SPACE_SIZE);
> +		(*num_roots)--;
> +	}
>   }
>   
> +DEFINE_FREE(amd_smn_release_config_regions, u16 *,
> +	    amd_smn_release_config_regions(_T));
> +
>   static bool enable_dfs;
>   
>   static int __init amd_smn_enable_dfs(char *str)
> @@ -259,9 +266,11 @@ __setup("amd_smn_debugfs_enable", amd_smn_enable_dfs);
>   
>   static int __init amd_smn_init(void)
>   {
> -	u16 count, num_roots, roots_per_node, node, num_nodes;
> +	u16 count, num_roots = 0, roots_per_node, node, num_nodes;
>   	struct pci_dev *root __free(pci_dev_put) = NULL;
>   
> +	u16 *config_regions __free(amd_smn_release_config_regions) = NULL;
> +
>   	if (!cpu_feature_enabled(X86_FEATURE_ZEN))
>   		return 0;
>   
> @@ -270,7 +279,8 @@ static int __init amd_smn_init(void)
>   	if (amd_roots)
>   		return 0;
>   
> -	num_roots = 0;
> +	config_regions = &num_roots;
> +
>   	while ((root = get_next_root(root))) {
>   		pci_dbg(root, "Reserving PCI config space\n");
>   
> @@ -282,7 +292,6 @@ static int __init amd_smn_init(void)
>   		 */
>   		if (!pci_request_config_region_exclusive(root, 0, PCI_CFG_SPACE_SIZE, NULL)) {
>   			pci_err(root, "Failed to reserve config space\n");
> -			amd_smn_release_config_regions(num_roots);

Did you forget to "remove" your v1 from the tree?  You should squash 
your v1 and v2 together as though it's one patch, not as though your v1 
was accepted.

I would just do this as a v3.

>   			return -EEXIST;
>   		}
>   
> @@ -297,7 +306,6 @@ static int __init amd_smn_init(void)
>   	num_nodes = amd_num_nodes();
>   	amd_roots = kzalloc_objs(*amd_roots, num_nodes);
>   	if (!amd_roots) {
> -		amd_smn_release_config_regions(num_roots);
>   		return -ENOMEM;
>   	}
>   
> @@ -327,6 +335,7 @@ static int __init amd_smn_init(void)
>   		debugfs_create_file("value",	0600, debugfs_dir, NULL, &smn_value_fops);
>   	}
>   
> +	config_regions = NULL;
>   	return 0;
>   }
>