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, 40 insertions, 0 deletions

diff --git a/drivers/sh/pm_runtime.c b/drivers/sh/pm_runtime.c
new file mode 100644
index 000000000..c887ecdaf
--- /dev/null
+++ b/drivers/sh/pm_runtime.c
@@ -0,0 +1,40 @@
+/*
+ * Runtime PM support code
+ *
+ *  Copyright (C) 2009-2010 Magnus Damm
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_clock.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/sh_clk.h>
+#include <linux/bitmap.h>
+#include <linux/slab.h>
+
+static struct dev_pm_domain default_pm_domain = {
+	.ops = {
+		USE_PM_CLK_RUNTIME_OPS
+		USE_PLATFORM_PM_SLEEP_OPS
+	},
+};
+
+static struct pm_clk_notifier_block platform_bus_notifier = {
+	.pm_domain = &default_pm_domain,
+	.con_ids = { NULL, },
+};
+
+static int __init sh_pm_runtime_init(void)
+{
+	pm_clk_add_notifier(&platform_bus_type, &platform_bus_notifier);
+	return 0;
+}
+core_initcall(sh_pm_runtime_init);