misc: xilinx-sdfec: remove check for ioctl cmd and argument.

if (_IOC_TYPE(cmd) != PP_IOCTL)
        return -ENOTTY;

Invalid ioctl command check normally performs by “default” case.

if (_IOC_DIR(cmd) != _IOC_NONE) {
       argp = (void __user *)arg;
       if (!argp)
             return -EINVAL; }

And for checking ioctl arguments, copy_from_user()/copy_to_user()
checks are enough.
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Harshal Chaudhari <harshalchau04@gmail.com>
Link: https://lore.kernel.org/r/20201101170949.18616-1-harshalchau04@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/xilinx_sdfec.c

@@ -944,8 +944,8 @@ static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd,
 			     unsigned long data)
 {
 	struct xsdfec_dev *xsdfec;
-	void __user *arg = NULL;
-	int rval = -EINVAL;
+	void __user *arg = (void __user *)data;
+	int rval;
 
 	xsdfec = container_of(fptr->private_data, struct xsdfec_dev, miscdev);
 
@@ -956,16 +956,6 @@ static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd,
 		return -EPERM;
 	}
 
-	if (_IOC_TYPE(cmd) != XSDFEC_MAGIC)
-		return -ENOTTY;
-
-	/* check if ioctl argument is present and valid */
-	if (_IOC_DIR(cmd) != _IOC_NONE) {
-		arg = (void __user *)data;
-		if (!arg)
-			return rval;
-	}
-
 	switch (cmd) {
 	case XSDFEC_START_DEV:
 		rval = xsdfec_start(xsdfec);
@@ -1010,7 +1000,7 @@ static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd,
 		rval = xsdfec_is_active(xsdfec, (bool __user *)arg);
 		break;
 	default:
-		/* Should not get here */
+		rval = -ENOTTY;
 		break;
 	}
 	return rval;