I'm having problems getting my ioctl function to write to user-space.
I call it from user space with this code:
/*======================*/
time_stamp ts;
if( ioctl(fd, ioct_num, &ts) )
{
printf("ioctl error %d %d\n", errno, sizeof(ts));
}
/*======================*/
My driver keeps failing at __generic_copy_to_user in the code below.
I don't see why it should not be able to copy to that address.
/*================================================*/
#define DEV_IOC_GET_TIMES _IOWR(DEV_IOCTL_TYPE, 1, time_stamp)
typedef struct _time_stamp
{
struct timeval write_last;
struct timeval write_now;
struct timeval irq_last;
struct timeval irq_now;
}time_stamp;
int dev_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
unsigned long arg)
{
int ret = 0;
int index1 = 0;
int index2 = 0;
int prev1 = 0;
int prev2 = 0;
time_stamp ts;
char * arg_ptr = (char *) arg;
if(_IOC_TYPE(cmd) != DEV_IOCTL_TYPE) return -ENOTTY;
if(_IOC_NR(cmd) > DEV_IOCTL_MAXNUM) return -ENOTTY;
switch(cmd)
{
case DEV_IOC_GET_TIMES:
/*
* return the last 2 times a usb irq was recieved
* and a write request was recieved
*/
if(arg_ptr == NULL)
{
printk("pointer is null\n");
return -EFAULT;
}
index1 = atomic_read(&wr_times_indx);
index2 = atomic_read(&irq_times_indx);
prev1 = prev_pos[index1];
prev2 = prev_pos[index2];
ts.write_now = write_times[index1];
ts.write_last= write_times[prev1];
ts.irq_now = irq_times[index2];
ts.irq_last= irq_times[prev2];
if( ret = __generic_copy_to_user(arg_ptr, ts,
sizeof(time_stamp)))
{
printk("copy to user failed %d %d\n", ret,
sizeof(time_stamp));
ret = -EFAULT;
}
break;
default:
return -ENOTTY;
}
return ret;
}
/*========================================================*/
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