Create a device driver, but when call the function ioctl , it say "ioctl(*, 0x* "

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Linux

Hi All,

Thank you for help.

I try to build a device driver and have build it Successfully.

When I call the ioctl system call, it prompts "Killed".

Then I run with strace command, it say "ioctl(3, 0x22 <unfinished ...=""> +++ killed by SIGKILL +++ Killed".

The related driver code is:

#define TEST_IOC_MAGIC 0x00
//Documentation/ioctl-number.txt say 0x00~0x1F are been used.
#define TEST_IOCRESET _IO(TEST_IOC_MAGIC, 0x22)
....
static const struct file_operations globalfifo_fops =
{
       .unlocked_ioctl = globalfifo_ioctl,

};
...
static int globalfifo_ioctl(struct inode *inode,struct file *filp,unsigned int cmd,unsigned long arg)
{
      ...
      case TEST_IOCRESET:
      ....
}

The related program code is:

int main()
{
      //  /dev/globalfifopoll is the device file.
      fd = open("/dev/globalfifopoll", O_CREAT|O_RDWR|O_NONBLOCK);
      ioctl(fd, TEST_IOCRESET, 0);
}

The device driver and the program are both build Successfully. Meanwhile, the device driver can work well when you write buffer data to it or read buffer data from it.

I don't know where is wrong. In the program, the function open() return value 3 to fd. But when run the code ioctl(), it says "ioctl(3, 0x22 <unfinished ...=""> ".

If I delete the code ioctl(fd, TEST_IOCRESET, 0), the program can run well.

Thank you for your help.