ftrace: Convert "inc" parameter to bool in ftrace_hash_rec_update_modify()

The parameter "inc" in the function ftrace_hash_rec_update_modify() is
boolean. Change it to be such.

Also add documentation to what the function does.

Link: https://lore.kernel.org/linux-trace-kernel/20240605180409.021080462@goodmis.org

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

kernel/trace/ftrace.c

@@ -1883,7 +1883,24 @@ static bool ftrace_hash_rec_enable(struct ftrace_ops *ops)
 	return __ftrace_hash_rec_update(ops, true);
 }
 
-static void ftrace_hash_rec_update_modify(struct ftrace_ops *ops, int inc)
+/*
+ * This function will update what functions @ops traces when its filter
+ * changes.
+ *
+ * The @inc states if the @ops callbacks are going to be added or removed.
+ * When one of the @ops hashes are updated to a "new_hash" the dyn_ftrace
+ * records are update via:
+ *
+ * ftrace_hash_rec_disable_modify(ops);
+ * ops->hash = new_hash
+ * ftrace_hash_rec_enable_modify(ops);
+ *
+ * Where the @ops is removed from all the records it is tracing using
+ * its old hash. The @ops hash is updated to the new hash, and then
+ * the @ops is added back to the records so that it is tracing all
+ * the new functions.
+ */
+static void ftrace_hash_rec_update_modify(struct ftrace_ops *ops, bool inc)
 {
 	struct ftrace_ops *op;
 
@@ -1907,12 +1924,12 @@ static void ftrace_hash_rec_update_modify(struct ftrace_ops *ops, int inc)
 
 static void ftrace_hash_rec_disable_modify(struct ftrace_ops *ops)
 {
-	ftrace_hash_rec_update_modify(ops, 0);
+	ftrace_hash_rec_update_modify(ops, false);
 }
 
 static void ftrace_hash_rec_enable_modify(struct ftrace_ops *ops)
 {
-	ftrace_hash_rec_update_modify(ops, 1);
+	ftrace_hash_rec_update_modify(ops, true);
 }
 
 /*