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, 57 insertions, 0 deletions

diff --git a/include/trace/syscall.h b/include/trace/syscall.h
new file mode 100644
index 000000000..0dd7f2b33
--- /dev/null
+++ b/include/trace/syscall.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TRACE_SYSCALL_H
+#define _TRACE_SYSCALL_H
+
+#include <linux/tracepoint.h>
+#include <linux/unistd.h>
+#include <linux/trace_events.h>
+#include <linux/thread_info.h>
+
+#include <asm/ptrace.h>
+
+
+/*
+ * A syscall entry in the ftrace syscalls array.
+ *
+ * @name: name of the syscall
+ * @syscall_nr: number of the syscall
+ * @nb_args: number of parameters it takes
+ * @user_arg_is_str: set if the arg for @user_arg_size is a string
+ * @user_arg_size: holds @arg that has size of the user space to read
+ * @user_mask: mask of @args that will read user space
+ * @types: list of types as strings
+ * @args: list of args as strings (args[i] matches types[i])
+ * @enter_fields: list of fields for syscall_enter trace event
+ * @enter_event: associated syscall_enter trace event
+ * @exit_event: associated syscall_exit trace event
+ */
+struct syscall_metadata {
+	const char	*name;
+	int		syscall_nr;
+	u8		nb_args:7;
+	u8		user_arg_is_str:1;
+	s8		user_arg_size;
+	short		user_mask;
+	const char	**types;
+	const char	**args;
+	struct list_head enter_fields;
+
+	struct trace_event_call *enter_event;
+	struct trace_event_call *exit_event;
+};
+
+#if defined(CONFIG_TRACEPOINTS) && defined(CONFIG_HAVE_SYSCALL_TRACEPOINTS)
+static inline void syscall_tracepoint_update(struct task_struct *p)
+{
+	if (test_syscall_work(SYSCALL_TRACEPOINT))
+		set_task_syscall_work(p, SYSCALL_TRACEPOINT);
+	else
+		clear_task_syscall_work(p, SYSCALL_TRACEPOINT);
+}
+#else
+static inline void syscall_tracepoint_update(struct task_struct *p)
+{
+}
+#endif
+
+#endif /* _TRACE_SYSCALL_H */