在做视频监控项目，以前一直用的是2.6.36的内核，一直很正常，但是这几天换3.0.1内核，启动程序，却出现了错误，如下：
./test_usb_camera
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
v4l2_open id=2
Unable to handle kernel NULL pointer dereference at virtual address 00000060
pgd = cbc08000
[00000060] *pgd=5c7d6831, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#2]
Modules linked in:
CPU: 0 Tainted: G D W (3.0.1 #676)
PC is at video_devdata+0x18/0x30
LR is at dev_open+0x28/0x194
pc : [<c0352fbc>] lr : [<c036359c>] psr: 60000013
sp : cc7f5d30 ip : cc7f5d40 fp : cc7f5d3c
r10: c081b880 r9 : 00000026 r8 : cc7e78c8
r7 : cc423008 r6 : cc7e78c8 r5 : cc7bc200 r4 : cc423000
r3 : 00000003 r2 : c089e880 r1 : 00000000 r0 : cc7e78c8
Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
Control: 00c5387d Table: 5bc08008 DAC: 00000015
Process test_usb_camera (pid: 77, stack limit = 0xcc7f4268)
Stack: (0xcc7f5d30 to 0xcc7f6000)
5d20: cc7f5d6c cc7f5d40 c036359c c0352fb0
5d40: c0363574 cc423000 cc7bc200 cc7e78c8 cc423008 cc7bc200 00000026 cc127180
5d60: cc7f5d8c cc7f5d70 c035333c c0363580 00000000 00000000 cc721ac0 cc7e78c8
5d80: cc7f5dbc cc7f5d90 c00ef5b0 c0353298 cc7f5e2c cc7f5ed0 00000000 cc7bc200
5da0: 00000000 cc7e78c8 c00ef490 cc127180 cc7f5df4 cc7f5dc0 c00ead14 c00ef49c
5dc0: cc080800 cc40ff00 cc7e78c8 cc7f5ed0 cc7bc200 00000000 cc7bce80 00000802
5de0: 00000026 00000000 cc7f5e1c cc7f5df8 c00eaf50 c00eabb4 cc7bce80 cc7f5e8c
5e00: cc7e78c8 cc7f5ed0 00000000 cc7f5e8c cc7f5e64 cc7f5e20 c00f8488 c00eaef4
5e20: cc7a3005 c088a480 cc7f5e64 cc40ff00 cc080800 cc7e78c8 cc7f5e64 cc7f5ed0
5e40: ffffff9c cc7f5f60 cc7f4000 cc7a3000 cc7f4000 cc7f5e8c cc7f5ec4 cc7f5e68
5e60: c00f992c c00f830c cc7f5e94 00000000 33db2580 00000000 66340397 bee98b70
5e80: 00000068 00000000 00000000 cc40ff00 cc127180 00000000 00000000 00000001
5ea0: cc7f5f60 cc7f5ed0 ffffff9c cc7a3000 cc7f4000 ffffff9c cc7f5f54 cc7f5ec8
5ec0: c00f9d04 c00f9874 00000041 00000000 cc40ff00 cc127180 d9d3cea0 00000006
5ee0: cc7a3005 cc40f820 cc07cc00 cc7e78c8 00000101 00000000 00000000 00000000
5f00: 00000000 00000000 00000004 cc7b50c0 cc7b50c8 cc7b50c4 00000000 cc7f4000
5f20: cc7f5f54 00000803 00000000 00000000 00000001 00000001 00000802 00000000
5f40: 00000004 cc7a3000 cc7f5f94 cc7f5f58 c00eaa78 c00f9cd8 00000000 00000000
5f60: 00000802 00000000 00000026 00000100 00000001 bee98e84 00067ecc 00000005
5f80: c0036ce8 00000000 cc7f5fa4 cc7f5f98 c00eab84 c00ea988 00000000 cc7f5fa8
5fa0: c0036b40 c00eab6c 00000001 bee98e84 000681c8 00000802 00000000 00085c8c
5fc0: 00000001 bee98e84 00067ecc 00000005 bee98d0c 00000000 000874b8 0000000a
5fe0: 00067ed4 bee98be0 000089b4 0001fe4c 40000010 000681c8 00000000 00000000
[<c0352fbc>] (video_devdata+0x18/0x30) from [<c036359c>] (dev_open+0x28/0x194)
[<c036359c>] (dev_open+0x28/0x194) from [<c035333c>] (v4l2_open+0xb0/0xd8)
[<c035333c>] (v4l2_open+0xb0/0xd8) from [<c00ef5b0>] (chrdev_open+0x120/0x1a4)
[<c00ef5b0>] (chrdev_open+0x120/0x1a4) from [<c00ead14>] (__dentry_open+0x16c/0x2c4)
[<c00ead14>] (__dentry_open+0x16c/0x2c4) from [<c00eaf50>] (nameidata_to_filp+0x68/0x70)
[<c00eaf50>] (nameidata_to_filp+0x68/0x70) from [<c00f8488>] (do_last+0x188/0x6b0)
[<c00f8488>] (do_last+0x188/0x6b0) from [<c00f992c>] (path_openat+0xc4/0x3a4)
[<c00f992c>] (path_openat+0xc4/0x3a4) from [<c00f9d04>] (do_filp_open+0x38/0x8c)
[<c00f9d04>] (do_filp_open+0x38/0x8c) from [<c00eaa78>] (do_sys_open+0xfc/0x1d0)
[<c00eaa78>] (do_sys_open+0xfc/0x1d0) from [<c00eab84>] (sys_open+0x24/0x28)
[<c00eab84>] (sys_open+0x24/0x28) from [<c0036b40>] (ret_fast_syscall+0x0/0x30)
Code: e24cb004 e590200c e5921020 e59f2010 (e5913060)
---[ end trace da227214a82491ba ]---
Segmentation fault
[root@Enjoylinux /]#
[root@Enjoylinux /]#
一直无法解决，不过这几天查到了一位大神的解决方法：
oks3c6410开发板 linux-3.0.1内核 ZC301P摄像头 构成视频监控系统时内核oops解决办法：
最近在做标题所示的视频监控系统时，加载飞凌提供的linux-3.0.1内核后，打开摄像头设备文件时内核报错，提示为段错误，搜索了相关问题，果然有人遇到同样问题，可惜时间久远，没有提供详细的解决方案，只提示说参照飞凌linux-2.6.36版本内核。于是，上干货，解决方法如下：
问题在于：在linux-3.0.1内核文件/include/v4l2-dev.h中，struct v4l2_file_operations函数集对open和release函数的定义，与/driver/media/video/gspca/gspca.c中dev_open(struct file *file)和 dev_close(struct file *file)函数定义存在出入。由于打开摄像头设备文件时会调用该函数(dev_open())，因此 需要将两处改成一样的定义。
v4l2-dev.h中struct v4l2_file_operations的定义为：
int (*open) (struct inode *inode,struct file *)
int (*release) (struct inode *inode,struct file *)
gspca.c中定义为：
dev_open(struct file *file)
dev_close(struct file *file)
修改后，gspca.c中定义不变，v4l2-dev.h中struct v4l2_file_operations的定义改为：
int (*open) (struct file *)
int (*release) (struct file *)
由于ZC301P摄像头参照gspca标准，其它摄像头可能参照uvc标准，为今后开发其它摄像头考虑，还需要修改/driver/media/video/uvc/uvc_v4l2.c中uvc_v4l2_open(struct inode *inode,struct file *file)函数和uvc_v4l2_release(struct inode *inode,struct file *file)函数，改后为：
uvc_v4l2_open(struct file *file)
uvc_v4l2_release(struct file *file)
最后，修改/driver/media/video/v4l2-dev.c文件中修改：
v4l2_open()函数下打开文件一行修改为ret = vdev->fops->open(filp)
v4l2_release()函数下释放文件一行修改为vdev->fops->release(filp);
至此完成。
根据大神的方法，修改以下几个地方，编译之后运行正常：
1./include/v4l2-dev.h 中struct v4l2_file_operations 修改为
int (*open) (struct file *)
int (*release) (struct file *)
2./driver/media/video/uvc/uvc_v4l2.c中
uvc_v4l2_open(struct inode *inode,struct file *file)函数
和uvc_v4l2_release(struct inode *inode,struct file *file)函数，
改后为：
uvc_v4l2_open(struct file *file)
uvc_v4l2_release(struct file *file)
3./driver/media/video/v4l2-dev.c
v4l2_open()函数下打开文件一行修改为ret = vdev->fops->open(filp)
v4l2_release()函数下释放文件一行修改为vdev->fops->release(filp);
Linux的世界水好深，继续加油！