Linux Kernel: Unable to load simple Linux kernel module with jobs

I am having a problem using working tiers in my Linux kernel module. My modules compile without any error, but it fails during load. I am unable to load the next module and get the following error in dmesg.

[root@nanderson test_mod]# insmod  workqueue_test.ko 
insmod: ERROR: could not insert module workqueue_test.ko: Unknown symbol in module
[root@nanderson test_mod]# dmesg -c
[50404.453417] workqueue_test: Unknown symbol destroy_workqueue (err 0)
[50404.453437] workqueue_test: Unknown symbol __alloc_workqueue_key (err 0)
[root@nanderson test_mod]# 

      

        
        
        
      

    

Following is the module code: -

  1 #include <linux/module.h>
  2 #include <linux/kernel.h>
  3 #include <linux/kthread.h>
  4 #include <linux/blkdev.h>
  5 #include <linux/fs.h> 
  6 #include <linux/delay.h>
  7 #include <linux/workqueue.h>
  8 #include <linux/completion.h>
  9
 10 
 11 #define LOG_ENTRY() \
 12     do {\
 13         printk(KERN_INFO "++ %s %d %s\n", __func__, __LINE__,\
 14                                         current->comm);\
 15     } while (0);
 16 
 17 #define LOG_INFO() \
 18     do {\
 19         printk(KERN_INFO "%s %d %s\n", __func__, __LINE__,\
 20                                         current->comm); mdelay(1000);\
 21     } while (0);
 22 
 23 #define LOG_EXIT() \
 24     do {\
 25         printk(KERN_INFO "-- %s %d %s\n", __func__, __LINE__,\
 26                                         current->comm);\
 27     } while (0);
 28 
 29 
 30 void
 31 async_callback(void *data)
 32 {
 33 
 34 }
 35 
 36 int
 37 init_module(void)
 38 {
 39     struct workqueue_struct *async_queue;
 40 
 41     LOG_ENTRY();
 42     if ((async_queue = create_workqueue("HGST_WORKQUEUE")) == NULL) {
 43          printk(KERN_ERR "failed to create workqueue\n");
 44          return -1;
 45     }    
 46          
 47     mdelay(10000);
 48     destroy_workqueue(async_queue);
 49     LOG_EXIT();
 50     return 0;
 51 }   
 52     
 53 
 54 void
 55 cleanup_module(void)
 56 {
 57     printk(KERN_INFO "Unloading MOdule..\n");
 58 }

      

        
        
        
      

    

I also looked at / proc / kallsysm for unknown characters that were sent by insmod, it looks like the characters available are as follows: -

[root@nanderson test_mod]# cat /proc/kallsyms  | grep __alloc_workqueue_key
ffffffff81084a10 T __alloc_workqueue_key
ffffffff8187a090 r __ksymtab___alloc_workqueue_key
ffffffff8188bd70 r __kcrctab___alloc_workqueue_key
ffffffff81892ba0 r __kstrtab___alloc_workqueue_key
[root@nanderson test_mod]# 

      

        
        
        
      

    

Can someone tell me what might be the problem or am I missing something?

Thank.