samples: Use KSYM_NAME_LEN for kprobes

It is better and enough to use KSYM_NAME_LEN for kprobes
in samples, no need to define and use the other values.

Link: https://lkml.kernel.org/r/1654651402-21552-1-git-send-email-yangtiezhu@loongson.cn

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: seehearfeel

samples/kprobes/kprobe_example.c

@@ -16,9 +16,8 @@
 #include <linux/module.h>
 #include <linux/kprobes.h>
 
-#define MAX_SYMBOL_LEN	64
-static char symbol[MAX_SYMBOL_LEN] = "kernel_clone";
-module_param_string(symbol, symbol, sizeof(symbol), 0644);
+static char symbol[KSYM_NAME_LEN] = "kernel_clone";
+module_param_string(symbol, symbol, KSYM_NAME_LEN, 0644);
 
 /* For each probe you need to allocate a kprobe structure */
 static struct kprobe kp = {

samples/kprobes/kretprobe_example.c

@@ -23,11 +23,10 @@
 #include <linux/module.h>
 #include <linux/kprobes.h>
 #include <linux/ktime.h>
-#include <linux/limits.h>
 #include <linux/sched.h>
 
-static char func_name[NAME_MAX] = "kernel_clone";
-module_param_string(func, func_name, NAME_MAX, S_IRUGO);
+static char func_name[KSYM_NAME_LEN] = "kernel_clone";
+module_param_string(func, func_name, KSYM_NAME_LEN, 0644);
 MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the"
 			" function's execution time");