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, 47 insertions, 0 deletions

diff --git a/include/soc/tegra/tegra-cbb.h b/include/soc/tegra/tegra-cbb.h
new file mode 100644
index 000000000..e864c2ebe
--- /dev/null
+++ b/include/soc/tegra/tegra-cbb.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2021-2022, NVIDIA CORPORATION. All rights reserved
+ */
+
+#ifndef TEGRA_CBB_H
+#define TEGRA_CBB_H
+
+#include <linux/list.h>
+
+struct tegra_cbb_error {
+	const char *code;
+	const char *source;
+	const char *desc;
+};
+
+struct tegra_cbb {
+	struct device *dev;
+	const struct tegra_cbb_ops *ops;
+	struct list_head node;
+};
+
+struct tegra_cbb_ops {
+	int (*debugfs_show)(struct tegra_cbb *cbb, struct seq_file *s, void *v);
+	int (*interrupt_enable)(struct tegra_cbb *cbb);
+	void (*error_enable)(struct tegra_cbb *cbb);
+	void (*fault_enable)(struct tegra_cbb *cbb);
+	void (*stall_enable)(struct tegra_cbb *cbb);
+	void (*error_clear)(struct tegra_cbb *cbb);
+	u32 (*get_status)(struct tegra_cbb *cbb);
+};
+
+int tegra_cbb_get_irq(struct platform_device *pdev, unsigned int *nonsec_irq,
+		      unsigned int *sec_irq);
+__printf(2, 3)
+void tegra_cbb_print_err(struct seq_file *file, const char *fmt, ...);
+
+void tegra_cbb_print_cache(struct seq_file *file, u32 cache);
+void tegra_cbb_print_prot(struct seq_file *file, u32 prot);
+int tegra_cbb_register(struct tegra_cbb *cbb);
+
+void tegra_cbb_fault_enable(struct tegra_cbb *cbb);
+void tegra_cbb_stall_enable(struct tegra_cbb *cbb);
+void tegra_cbb_error_clear(struct tegra_cbb *cbb);
+u32 tegra_cbb_get_status(struct tegra_cbb *cbb);
+
+#endif /* TEGRA_CBB_H */