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, 74 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/hotplug.c b/arch/arm/mach-tegra/hotplug.c
new file mode 100644
index 000000000..5c907c2c0
--- /dev/null
+++ b/arch/arm/mach-tegra/hotplug.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Copyright (C) 2002 ARM Ltd.
+ *  All Rights Reserved
+ *  Copyright (c) 2010, 2012-2013, NVIDIA Corporation. All rights reserved.
+ */
+
+#include <linux/clk/tegra.h>
+#include <linux/kernel.h>
+#include <linux/smp.h>
+
+#include <soc/tegra/common.h>
+#include <soc/tegra/fuse.h>
+
+#include <asm/smp_plat.h>
+
+#include "common.h"
+#include "sleep.h"
+
+static void (*tegra_hotplug_shutdown)(void);
+
+int tegra_cpu_kill(unsigned cpu)
+{
+	cpu = cpu_logical_map(cpu);
+
+	/* Clock gate the CPU */
+	tegra_wait_cpu_in_reset(cpu);
+	tegra_disable_cpu_clock(cpu);
+
+	return 1;
+}
+
+/*
+ * platform-specific code to shutdown a CPU
+ *
+ * Called with IRQs disabled
+ */
+void tegra_cpu_die(unsigned int cpu)
+{
+	if (!tegra_hotplug_shutdown) {
+		WARN(1, "hotplug is not yet initialized\n");
+		return;
+	}
+
+	/* Clean L1 data cache */
+	tegra_disable_clean_inv_dcache(TEGRA_FLUSH_CACHE_LOUIS);
+
+	/* Shut down the current CPU. */
+	tegra_hotplug_shutdown();
+
+	/* Should never return here. */
+	BUG();
+}
+
+static int __init tegra_hotplug_init(void)
+{
+	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
+		return 0;
+
+	if (!soc_is_tegra())
+		return 0;
+
+	if (IS_ENABLED(CONFIG_ARCH_TEGRA_2x_SOC) && tegra_get_chip_id() == TEGRA20)
+		tegra_hotplug_shutdown = tegra20_hotplug_shutdown;
+	if (IS_ENABLED(CONFIG_ARCH_TEGRA_3x_SOC) && tegra_get_chip_id() == TEGRA30)
+		tegra_hotplug_shutdown = tegra30_hotplug_shutdown;
+	if (IS_ENABLED(CONFIG_ARCH_TEGRA_114_SOC) && tegra_get_chip_id() == TEGRA114)
+		tegra_hotplug_shutdown = tegra30_hotplug_shutdown;
+	if (IS_ENABLED(CONFIG_ARCH_TEGRA_124_SOC) && tegra_get_chip_id() == TEGRA124)
+		tegra_hotplug_shutdown = tegra30_hotplug_shutdown;
+
+	return 0;
+}
+pure_initcall(tegra_hotplug_init);