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/include/trace/events/syscalls.h b/include/trace/events/syscalls.h
new file mode 100644
index 000000000..f31ff446b
--- /dev/null
+++ b/include/trace/events/syscalls.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM raw_syscalls
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE syscalls
+
+#if !defined(_TRACE_EVENTS_SYSCALLS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_EVENTS_SYSCALLS_H
+
+#include <linux/tracepoint.h>
+
+#include <asm/ptrace.h>
+#include <asm/syscall.h>
+
+
+#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
+
+TRACE_EVENT_SYSCALL(sys_enter,
+
+	TP_PROTO(struct pt_regs *regs, long id),
+
+	TP_ARGS(regs, id),
+
+	TP_STRUCT__entry(
+		__field(	long,		id		)
+		__array(	unsigned long,	args,	6	)
+	),
+
+	TP_fast_assign(
+		__entry->id	= id;
+		syscall_get_arguments(current, regs, __entry->args);
+	),
+
+	TP_printk("NR %ld (%lx, %lx, %lx, %lx, %lx, %lx)",
+		  __entry->id,
+		  __entry->args[0], __entry->args[1], __entry->args[2],
+		  __entry->args[3], __entry->args[4], __entry->args[5]),
+
+	syscall_regfunc, syscall_unregfunc
+);
+
+TRACE_EVENT_FLAGS(sys_enter, TRACE_EVENT_FL_CAP_ANY)
+
+TRACE_EVENT_SYSCALL(sys_exit,
+
+	TP_PROTO(struct pt_regs *regs, long ret),
+
+	TP_ARGS(regs, ret),
+
+	TP_STRUCT__entry(
+		__field(	long,	id	)
+		__field(	long,	ret	)
+	),
+
+	TP_fast_assign(
+		__entry->id	= syscall_get_nr(current, regs);
+		__entry->ret	= ret;
+	),
+
+	TP_printk("NR %ld = %ld",
+		  __entry->id, __entry->ret),
+
+	syscall_regfunc, syscall_unregfunc
+);
+
+TRACE_EVENT_FLAGS(sys_exit, TRACE_EVENT_FL_CAP_ANY)
+
+#endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
+
+#endif /* _TRACE_EVENTS_SYSCALLS_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
+