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x86/amd_node: Fix PCI device reference counting in amd_smn_init()

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The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com
This commit is contained in:
Yazen Ghannam
2026-09-10 18:05:43 -07:00
committed by Borislav Petkov (AMD)
parent f65d38155a
commit 27600805e6
1 changed files with 2 additions and 4 deletions
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arch/x86/kernel/amd_node.c
+2 -4
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@@ -251,7 +251,7 @@ __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;
struct pci_dev *root;
struct pci_dev *root __free(pci_dev_put) = NULL;
if (!cpu_feature_enabled(X86_FEATURE_ZEN))
return 0;
@@ -262,7 +262,6 @@ static int __init amd_smn_init(void)
return 0;
num_roots = 0;
root = NULL;
while ((root = get_next_root(root))) {
pci_dbg(root, "Reserving PCI config space\n");
@@ -299,14 +298,13 @@ static int __init amd_smn_init(void)
count = 0;
node = 0;
root = NULL;
while (node < num_nodes && (root = get_next_root(root))) {
/* Use one root for each node and skip the rest. */
if (count++ % roots_per_node)
continue;
pci_dbg(root, "is root for AMD node %u\n", node);
amd_roots[node++] = root;
amd_roots[node++] = pci_dev_get(root);
}
if (enable_dfs) {