我正在编写petalinux的驱动程序，但是v4l2 ioctl函数存在一些问题，尤其是ioctl(fd, VIDIOC_STREAMON, &type)。当我致电streamon时，有时我会收到以下错误消息：
[ 899.083253]Unable to handle kernel NULL pointer dereference at virtual address 0000000000000001
[ 899.092044] Mem abort info:
[ 899.094832] ESR = 0x96000021
[ 899.097875] Exception class = DABT (current EL), IL = 32 bits
[ 899.103787] SET = 0, FnV = 0
[ 899.106833] EA = 0, S1PTW = 0
[ 899.109967] Data abort info:
[ 899.112836] ISV = 0, ISS = 0x00000021
[ 899.116661] CM = 0, WnR = 0
[ 899.119622] user pgtable: 4k pages, 39-bit VAs, pgdp = (____ptrval____)
[ 899.126228] [0000000000000001] pgd=0000000000000000, pud=0000000000000000
[ 899.133018] Internal error: Oops: 96000021 [#1] SMP
[ 899.137881] Modules linked in: video(O) al5d(O) al5e(O) allegro(O) xlnx_vcu_clk xlnx_vcu xilinx_hdmi_rx(O) xilinx_vphy(O) xlnx_vcu_core mali(O) uio_pdrv_genirq [last unloaded: video]
[ 899.154143] CPU: 0 PID: 2322 Comm: test Tainted: G W O 4.19.0-xilinx-v2019.1 #1
[ 899.162568] Hardware name: ZynqMP ZCU106 RevA (DT)
[ 899.167345] pstate: a0000005 (NzCv daif -PAN -UAO)
[ 899.172125] pc : __ll_sc___cmpxchg_case_acq_8+0x4/0x20
[ 899.177251] lr : mutex_lock_interruptible+0x18/0x40
[ 899.182118] sp : ffffff8010c73bb0
[ 899.185416] x29: ffffff8010c73bb0 x28: ffffffc87af98000
[ 899.190720] x27: ffffff8008769108 x26: ffffff8000c9b1f8
[ 899.196024] x25: 0000007fc63db5c4 x24: 0000000000000001
[ 899.201319] x23: 0000000000000000 x22: ffffff8009138648
[ 899.206615] x21: 0000000000000012 x20: 0000000040045612
[ 899.211910] x19: ffffffc879d60800 x18: 0000000000000000
[ 899.217205] x17: 0000000000000000 x16: 0000000000000000
[ 899.222501] x15: 0000000000000000 x14: 0000000000000000
[ 899.227796] x13: 0000000000000000 x12: 0000000000000000
[ 899.233091] x11: 0000000000000000 x10: 0000000000000000
[ 899.238387] x9 : 0000000000000000 x8 : 0000000000000000
[ 899.243682] x7 : 0000000000000000 x6 : ffffffc87b942080
[ 899.248977] x5 : 00000000ffffffff x4 : ffffff800876cea0
[ 899.254281] x3 : 0000000000000001 x2 : ffffffc87ac2f400
[ 899.259577] x1 : 0000000000000000 x0 : 0000000000000001
[ 899.264873] Process test (pid: 2322, stack limit = 0x(____ptrval____))
[ 899.271383] Call trace:
[ 899.273817] __ll_sc___cmpxchg_case_acq_8+0x4/0x20
[ 899.278600] __video_do_ioctl+0x124/0x498
[ 899.282600] video_usercopy+0x144/0x518
[ 899.286420] video_ioctl2+0x14/0x1c
[ 899.289894] v4l2_ioctl+0x3c/0x58
[ 899.293202] do_vfs_ioctl+0xb8/0x8a0
[ 899.296768] ksys_ioctl+0x44/0x90
[ 899.300067] __arm64_sys_ioctl+0x1c/0x28
[ 899.303975] el0_svc_common+0x84/0xd8
[ 899.307627] el0_svc_handler+0x68/0x80
[ 899.311360] el0_svc+0x8/0xc
[ 899.314226] Code: 35ffff91 aa1003e0 d65f03c0 f9800011 (c85ffc10)
[ 899.320310] ---[ end trace da93a42a8cf31bfc ]---
Segmentation fault
我试图四次致电VIDIOC_STREAMON：
如果再次测试，我会得到不同的结果。错误与我的驱动程序或内核有关吗？
这是我的streamon函数，但是在vidioc_streamon内的所有代码都被注释时，也会出现错误
static int vidioc_streamon(struct file *file, void *fh, enum v4l2_buf_type t){
int ret = -1;
if( t == V4L2_BUF_TYPE_VIDEO_CAPTURE )
skel->ready_for_capture = 1;
switch( t ){
case V4L2_BUF_TYPE_VIDEO_OUTPUT: skel->ready_for_output = 0;
if (!skel->ready_for_capture) {
ret = allocate_buffers(skel);
if (ret < 0)
return ret;
skel->ready_for_capture = 1;
}
return 0;
case V4L2_BUF_TYPE_VIDEO_CAPTURE: if( !skel->ready_for_capture ){
printk(KERN_ERR "Streamon, capture not ready");
return -EIO;
}
printk(KERN_INFO "Streamon, capture ready");
printk(KERN_INFO "");
return 0;
default: printk(KERN_INFO "INVALID BUF_TYPE");
return -EINVAL;
}
return -EINVAL;
}
在模块加载期间，我收到此警告
[ 29.165507] ------------[ cut here ]------------
[ 29.173531] refcount_t: increment on 0; use-after-free.
[ 29.178787] WARNING: CPU: 3 PID: 2295 at lib/refcount.c:153 refcount_inc_checked+0x40/0x48
[ 29.187038] Modules linked in: video(O+) al5d(O) al5e(O) allegro(O) xlnx_vcu_clk xlnx_vcu xilinx_hdmi_rx(O) xilinx_vphy(O) xlnx_vcu_core mali(O) uio_pdrv_genirq [last unloaded: video]
[ 29.203388] CPU: 3 PID: 2295 Comm: insmod Tainted: G O 4.19.0-xilinx-v2019.1 #1
[ 29.211987] Hardware name: ZynqMP ZCU106 RevA (DT)
[ 29.216764] pstate: 60000005 (nZCv daif -PAN -UAO)
[ 29.221538] pc : refcount_inc_checked+0x40/0x48
[ 29.226052] lr : refcount_inc_checked+0x40/0x48
[ 29.230564] sp : ffffff8010f7b8f0
[ 29.233863] x29: ffffff8010f7b8f0 x28: ffffffc87aebb1b8
[ 29.239167] x27: ffffff800920fc18 x26: ffffffc87aebb000
[ 29.244471] x25: 0000000000000001 x24: ffffff8008d9c6d8
[ 29.249775] x23: 0000000000000000 x22: ffffff8008bfc7c8
[ 29.255079] x21: ffffff800918dc28 x20: ffffff8009138648
[ 29.260374] x19: 0000000000000001 x18: 0000000000000010
[ 29.265669] x17: 0000000000000000 x16: 0000000000000000
[ 29.270965] x15: ffffffffffffffff x14: ffffff8009138648
[ 29.276269] x13: ffffff80891d6f0f x12: ffffff80091d6f17
[ 29.281564] x11: ffffff800914a000 x10: ffffff8010f7b5d0
[ 29.286859] x9 : ffffff8009138648 x8 : ffffff8008569d70
[ 29.292163] x7 : 2d657375203b3020 x6 : 0000000000000189
[ 29.297458] x5 : 0000000000000001 x4 : 0000000000000000
[ 29.302754] x3 : 0000000000000000 x2 : ffffffffffffffff
[ 29.308049] x1 : c29b4d7389105500 x0 : 0000000000000000
[ 29.313345] Call trace:
[ 29.315778] refcount_inc_checked+0x40/0x48
[ 29.319947] __video_register_device+0x5f8/0xf00
[ 29.324561] video_probe+0x394/0x550 [video]
[ 29.328818] platform_drv_probe+0x50/0xa0
[ 29.332818] really_probe+0x1c8/0x280
[ 29.336463] driver_probe_device+0x54/0xe8
[ 29.340544] __driver_attach+0xe4/0xe8
[ 29.344276] bus_for_each_dev+0x70/0xc0
[ 29.348096] driver_attach+0x20/0x28
[ 29.351655] bus_add_driver+0x1dc/0x208
[ 29.355475] driver_register+0x60/0x110
[ 29.359295] __platform_driver_register+0x44/0x50
[ 29.363986] video_init+0x28/0x1000 [video]
[ 29.368159] do_one_initcall+0x74/0x178
[ 29.371987] do_init_module+0x54/0x1c8
[ 29.375719] load_module+0x1b5c/0x20e0
[ 29.379451] __se_sys_finit_module+0xb8/0xc8
[ 29.383705] __arm64_sys_finit_module+0x18/0x20
[ 29.388220] el0_svc_common+0x84/0xd8
[ 29.391874] el0_svc_handler+0x68/0x80
[ 29.395606] el0_svc+0x8/0xc
[ 29.398470] ---[ end trace 6a49c9f1f8cce610 ]---