Linux Kernel : Not able to load simple linux kernel module with workqueues -


i'm having issue using workqueues in linux kernel module. modules compiles without giving error @ time of loading fails. i'm not able load following module , getting following error in dmesg.

[root@nanderson test_mod]# insmod  workqueue_test.ko  insmod: error: 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 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     {\  13         printk(kern_info "++ %s %d %s\n", __func__, __line__,\  14                                         current->comm);\  15     } while (0);  16   17 #define log_info() \  18     {\  19         printk(kern_info "%s %d %s\n", __func__, __line__,\  20                                         current->comm); mdelay(1000);\  21     } while (0);  22   23 #define log_exit() \  24     {\  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 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 looked /proc/kallsysm unknown symbols reposted insmod looks symbols available following output:-

[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 tell me might problem or i'm missing ?

thanks.

you need

module_license("gpl");

in code use gpl symbols (exported using export_symbol_gpl).

otherwise module loader not see such symbols.


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