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

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: 0a4b61d9c2e4 ("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

1 files changed, 37 insertions, 0 deletions

diff --git a/fs/sysctls.c b/fs/sysctls.c
new file mode 100644
index 000000000..ad429dffe
--- /dev/null
+++ b/fs/sysctls.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * /proc/sys/fs shared sysctls
+ *
+ * These sysctls are shared between different filesystems.
+ */
+#include <linux/init.h>
+#include <linux/sysctl.h>
+
+static const struct ctl_table fs_shared_sysctls[] = {
+	{
+		.procname	= "overflowuid",
+		.data		= &fs_overflowuid,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_MAXOLDUID,
+	},
+	{
+		.procname	= "overflowgid",
+		.data		= &fs_overflowgid,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_MAXOLDUID,
+	},
+};
+
+static int __init init_fs_sysctls(void)
+{
+	register_sysctl_init("fs", fs_shared_sysctls);
+	return 0;
+}
+
+early_initcall(init_fs_sysctls);