Commit a54665ab authored Apr 16, 2025 by Steven Rostedt Committed by Steven Rostedt (Google) May 08, 2025

ftrace: Comment that ftrace_func_mapper is freed with free_ftrace_hash()

The structure ftrace_func_mapper only contains a single field and that is
a ftrace_hash. It is used to abstract it out from a normal hash to control
users of how it gets modified.

The freeing of a ftrace_func_mapper structure is:

  free_ftrace_hash(&mapper->hash);

Without context, this looks like a bug. It should be commented that it is
not a bug and it is freed this way.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/20250416165420.5c717420@gandalf.local.home


Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

parent 761ef342

kernel/trace/ftrace.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -5208,8 +5208,12 @@ struct ftrace_func_map {
		void *data;
		};

		/*
		* Note, ftrace_func_mapper is freed by free_ftrace_hash(&mapper->hash).
		* The hash field must be the first field.
		*/
		struct ftrace_func_mapper {
		struct ftrace_hash hash;
		struct ftrace_hash hash; /* Must be first! */
		};

		/**
		@@ -5344,6 +5348,7 @@ void free_ftrace_func_mapper(struct ftrace_func_mapper *mapper,
		}
		}
		}
		/* This also frees the mapper itself */
		free_ftrace_hash(&mapper->hash);
		}