块设备驱动在add_disk的时候出问题了……

小菜虎

我编写的块设备驱动加载不上，经测试，程序卡在运行add_disk函数的时候。麻烦大大们帮我找下BUG谢谢{:3_194:} demsg日志和源代码如下：

[  174.489539] MyBlk init done.
[  174.489542] bop init done.
[  174.489548] bdisk alloc done.
[  174.489549] bdisk init done.
[  174.489571] bqueue alloc done.
[  174.489573] bqueue make request done.
[  174.489580] Register blkdev done.
[  174.489586] BUG: unable to handle kernel NULL pointer dereference at 0000021c
[  174.489599] IP: [<c11305b0>] bdi_register+0x10/0x100
[  174.489608] *pdpt = 0000000030d40001 *pde = 0000000000000000
[  174.489614] Oops: 0000 [#1] SMP
[  174.489619] Modules linked in: hello(OF+) bnep rfcomm bluetooth snd_hda_codec_hdmi x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel(F) kvm(F) crc32_pclmul(F) ppdev(F) eeepc_wmi asus_wmi sparse_keymap cdc_acm nouveau microcode(F) snd_hda_codec_realtek mxm_wmi ttm lpc_ich drm_kms_helper serio_raw(F) snd_hda_intel mei_me snd_hda_codec parport_pc(F) video(F) snd_hwdep(F) snd_pcm(F) drm snd_seq_midi(F) snd_seq_midi_event(F) snd_rawmidi(F) snd_page_alloc(F) snd_seq(F) snd_seq_device(F) snd_timer(F) i2c_algo_bit mei snd(F) wmi mac_hid soundcore(F) lp(F) parport(F) hid_generic usbhid hid r8169 mii(F)
[  174.489700] CPU: 1 PID: 2404 Comm: insmod Tainted: GF          O 3.11.0-12-generic #19-Ubuntu
[  174.489704] Hardware name: System manufacturer System Product Name/P8H61-M LX, BIOS 0601 08/31/2011
[  174.489709] task: f1813380 ti: f0cec000 task.ti: f0cec000
[  174.489713] EIP: 0060:[<c11305b0>] EFLAGS: 00010296 CPU: 1
[  174.489717] EIP is at bdi_register+0x10/0x100
[  174.489720] EAX: 000000d0 EBX: 000000d0 ECX: 00000000 EDX: 000000f8
[  174.489724] ESI: f1b4fc5c EDI: 00000000 EBP: f0cedd8c ESP: f0cedd78
[  174.489728]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[  174.489732] CR0: 80050033 CR2: 0000021c CR3: 30d4e000 CR4: 000407f0
[  174.489735] Stack:
[  174.489738]  00000330 00000015 00000001 f1b4fc00 f1b4fc5c f0cedda8 c11306d6 000000d0
[  174.489750]  00000000 c1871a1e 000000f8 00000000 f0cedde8 c12d9b8e 00000001 00000246
[  174.489761]  00000000 00000000 f1b4fc0c 00000001 0f800000 c1621d72 00000000 00000001
[  174.489773] Call Trace:
[  174.489778]  [<c11306d6>] bdi_register_dev+0x36/0x40
[  174.489784]  [<c12d9b8e>] add_disk+0x11e/0x430
[  174.489789]  [<c1621d72>] ? printk+0x50/0x52
[  174.489794]  [<ff6ff000>] ? 0xff6fefff
[  174.489798]  [<ff6ff14f>] init_module+0x14f/0x1000 [hello]
[  174.489804]  [<c10020ca>] do_one_initcall+0xca/0x190
[  174.489808]  [<ff6ff000>] ? 0xff6fefff
[  174.489813]  [<c104871f>] ? set_memory_nx+0x5f/0x70
[  174.489818]  [<c10b4a8e>] load_module+0x10ce/0x18d0
[  174.489824]  [<c10b531f>] SyS_init_module+0x8f/0xf0
[  174.489831]  [<c1632ccd>] sysenter_do_call+0x12/0x28
[  174.489835] Code: 5d c3 c7 45 b8 00 00 00 00 e9 83 fe ff ff 8d b6 00 00 00 00 8d bc 27 00 00 00 00 55 89 e5 56 53 83 ec 0c 66 66 66 66 90 8b 5d 08 <8b> 83 4c 01 00 00 85 c0 74 0e 31 c0 83 c4 0c 5b 5e 5d c3 90 8d
[  174.490116] EIP: [<c11305b0>] bdi_register+0x10/0x100 SS:ESP 0068:f0cedd78
[  174.490164] CR2: 000000000000021c
[  174.512496] ---[ end trace 66605d80150e4d51 ]---

1. 
   
2. /*hello.c*/
   
3. #include <linux/init.h>
   
4. #include <linux/module.h>
   
5. #include <linux/fs.h>
   
6. #include <linux/blkdev.h>
   
7. #include <linux/genhd.h>
   
8. #include <linux/bio.h>
   
9. #include "myblk.h"
   
10. 
    
11. #define MYBLK_DEV_SIZE 200
    
12. #define MYBLK_DEV_MAJOR 248
    
13. #define MYBLK_DEV_NAME "MyBlkDev"
    
14. 
    
15. struct MyBlk *blk;
    
16. struct block_device_operations bop;
    
17. struct gendisk *bdisk;
    
18. struct request_queue *bqueue;
    
19. 
    
20. int open(struct inode *node, struct file *fp)
    
21. {
    
22.         return 0;
    
23. }
    
24. 
    
25. int release(struct inode *node, struct file *fp)
    
26. {
    
27.         return 0;
    
28. }
    
29. 
    
30. void myblk_make_request(struct request_queue *q, struct bio *bio)
    
31. {
    
32.         int i;
    
33.         char *buf;
    
34.         char *mem;
    
35.         struct bio_vec *bvl;
    
36.         if(((bio->bi_sector)<<9) + bio->bi_size > (MYBLK_DEV_SIZE<<9))
    
37.         {
    
38.                 bio_io_error(bio);
    
39.                 //return 0;
    
40.         }
    
41.         mem = blk->mem + ((bio->bi_sector)<<9);
    
42.         bio_for_each_segment(bvl, bio, i)
    
43.         {
    
44.                 buf = __bio_kmap_atomic(bio,i/*,KM_USER0*/);
    
45.                 switch(bio_data_dir(bio))
    
46.                 {
    
47.                         case READ:
    
48.                         case READA:
    
49.                                 memcpy(buf, mem, bvl->bv_len);
    
50.                                 break;
    
51.                         case WRITE:
    
52.                                 memcpy(mem, buf, bvl->bv_len);
    
53.                                 break;
    
54.                         default:
    
55.                                 break;
    
56.                 }
    
57.                 __bio_kunmap_atomic(buf/*, KM_USER0*/);
    
58.                 mem += bvl->bv_len;
    
59.         }
    
60.         bio_endio(bio, /*bio->bi_size,*/ 0);
    
61.         //return 0;
    
62. }
    
63. 
    
64. int __init hello_init(void)
    
65. {
    
66.         blk = MyBlk_init(MYBLK_DEV_SIZE);
    
67.         if(blk == NULL)
    
68.         {
    
69.                 printk(KERN_ALERT"Error init MyBlk.\n");
    
70.                 return -1;
    
71.         }
    
72.         printk(KERN_ALERT"MyBlk init done.\n");
    
73.         //bop.open = open;
    
74.         //bop.release = release;
    
75.         bop.owner = THIS_MODULE;
    
76.         printk(KERN_ALERT"bop init done.\n");
    
77.         bdisk = alloc_disk(1);
    
78.         if(bdisk == NULL)
    
79.         {
    
80.                 printk(KERN_ALERT"bdisk alloc error.\n");
    
81.                 return -1;
    
82.         }
    
83.         printk(KERN_ALERT"bdisk alloc done.\n");
    
84.         bdisk->major = MYBLK_DEV_MAJOR;
    
85.         bdisk->first_minor = 0;
    
86.         bdisk->fops = &bop;
    
87.         set_capacity(bdisk, MYBLK_DEV_SIZE);
    
88.         strcpy(bdisk->disk_name, MYBLK_DEV_NAME);
    
89.         printk(KERN_ALERT"bdisk init done.\n");
    
90.         /*************************/
    
91.         bqueue = blk_alloc_queue(GFP_KERNEL);
    
92.         if(bqueue == NULL)
    
93.         {
    
94.                 printk(KERN_ALERT"Error blk_alloc_queue\n");
    
95.                 return -1;
    
96.         }
    
97.         printk(KERN_ALERT"bqueue alloc done.\n");
    
98.         blk_queue_make_request(bqueue, myblk_make_request);
    
99.         printk(KERN_ALERT"bqueue make request done.\n");
    
100.         //blk_queue_max_sectors(bqueue, MYBLK_DEV_SIZE);
     
101.         /*************************/
     
102.         if(0 > register_blkdev(MYBLK_DEV_MAJOR, MYBLK_DEV_NAME))
     
103.         {
     
104.                 printk(KERN_ALERT"Register_blkdev error\n");
     
105.                 return -1;
     
106.         }
     
107.         printk(KERN_ALERT"Register blkdev done.\n");
     
108.         add_disk(bdisk);
     
109.         printk(KERN_ALERT"Hello world!\n");
     
110.         return 0;
     
111. }
     
112. void __exit hello_exit(void)
     
113. {
     
114.         MyBlk_uninit(blk);
     
115.         blk_cleanup_queue(bqueue);
     
116.         del_gendisk(bdisk);
     
117.         unregister_blkdev(MYBLK_DEV_MAJOR, MYBLK_DEV_NAME);
     
118.         printk(KERN_ALERT"Goodbye world!\n");
     
119. }
     
120. 
     
121. module_init(hello_init);
     
122. module_exit(hello_exit);
     
123. 
     
124. MODULE_LICENSE("Dual BSD/GPL");
     
125. MODULE_AUTHOR("Xiaocaihu");
     
126. MODULE_VERSION("1.0");
     

复制代码

1. 
   
2. /*myblk.h*/
   
3. #include <linux/slab.h>
   
4. struct MyBlk
   
5. {
   
6.         char* mem;
   
7.         sector_t size;
   
8. };
   
9. 
   
10. struct MyBlk* MyBlk_init(sector_t size)
    
11. {
    
12.         struct MyBlk *blk;
    
13.         blk = kmalloc(sizeof(struct MyBlk), GFP_KERNEL);
    
14.         if(blk == NULL)
    
15.         {
    
16.                 printk(KERN_ALERT"blk alloc error!\n");
    
17.                 return NULL;
    
18.         }
    
19.         blk->size = size;
    
20.         blk->mem = kmalloc(size<<9, GFP_KERNEL);
    
21.         if(blk->mem == NULL)
    
22.         {
    
23.                 printk(KERN_ALERT"Mem alloc error!\n");
    
24.                 kfree(blk);
    
25.                 return NULL;
    
26.         }
    
27.         return blk;
    
28. }
    
29. 
    
30. void MyBlk_uninit(struct MyBlk *blk)
    
31. {
    
32.         if(blk && blk->mem)
    
33.                 kfree(blk->mem);
    
34.         if(blk)
    
35.                 kfree(blk);
    
36. }
    

复制代码

humjb_1983

非法地址访问，需要反汇编看看具体出错的代码行和具体变量，确认变量的来源，看看是不是你传入的参数有问题。

小菜虎

回复 2# humjb_1983


    谢谢你的回复，可我还是不知道问题出在哪儿……

小菜虎

回复 2# humjb_1983


    找到问题了。我忘了把请求队列赋值给gendisk，低级失误啊{:3_204:}

在hello.c文件的第99行和第100行之间插入代码：

1. 
   
2. bdisk->queue = bqueue;
   

复制代码

问题解决{:3_200:}

再次感谢你的回复

humjb_1983

呵呵，找到问题就好，此类问题通常是自己编写的代码所致，内核中稍不留神就这样~，坑踩多了就好了