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, 72 insertions, 0 deletions

diff --git a/include/soc/tegra/pm.h b/include/soc/tegra/pm.h
new file mode 100644
index 000000000..ce4d0b1bd
--- /dev/null
+++ b/include/soc/tegra/pm.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2014 NVIDIA Corporation
+ */
+
+#ifndef __SOC_TEGRA_PM_H__
+#define __SOC_TEGRA_PM_H__
+
+#include <linux/errno.h>
+
+enum tegra_suspend_mode {
+	TEGRA_SUSPEND_NONE = 0,
+	TEGRA_SUSPEND_LP2, /* CPU voltage off */
+	TEGRA_SUSPEND_LP1, /* CPU voltage off, DRAM self-refresh */
+	TEGRA_SUSPEND_LP0, /* CPU + core voltage off, DRAM self-refresh */
+	TEGRA_MAX_SUSPEND_MODE,
+	TEGRA_SUSPEND_NOT_READY,
+};
+
+#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_ARM) && defined(CONFIG_ARCH_TEGRA)
+enum tegra_suspend_mode
+tegra_pm_validate_suspend_mode(enum tegra_suspend_mode mode);
+
+/* low-level resume entry point */
+void tegra_resume(void);
+
+int tegra30_pm_secondary_cpu_suspend(unsigned long arg);
+void tegra_pm_clear_cpu_in_lp2(void);
+void tegra_pm_set_cpu_in_lp2(void);
+int tegra_pm_enter_lp2(void);
+int tegra_pm_park_secondary_cpu(unsigned long cpu);
+void tegra_pm_init_suspend(void);
+#else
+static inline enum tegra_suspend_mode
+tegra_pm_validate_suspend_mode(enum tegra_suspend_mode mode)
+{
+	return TEGRA_SUSPEND_NONE;
+}
+
+static inline void tegra_resume(void)
+{
+}
+
+static inline int tegra30_pm_secondary_cpu_suspend(unsigned long arg)
+{
+	return -ENOTSUPP;
+}
+
+static inline void tegra_pm_clear_cpu_in_lp2(void)
+{
+}
+
+static inline void tegra_pm_set_cpu_in_lp2(void)
+{
+}
+
+static inline int tegra_pm_enter_lp2(void)
+{
+	return -ENOTSUPP;
+}
+
+static inline int tegra_pm_park_secondary_cpu(unsigned long cpu)
+{
+	return -ENOTSUPP;
+}
+
+static inline void tegra_pm_init_suspend(void)
+{
+}
+#endif /* CONFIG_PM_SLEEP */
+
+#endif /* __SOC_TEGRA_PM_H__ */