ieee1394: mark char device files as not seekable

The
  - raw1394   (/dev/raw1394),
  - video1394 (/dev/video1394/*),
  - dv1394    (/dev/dv1394/*)
character device file ABIs do not make any use of lseek(), pread(), or
pwrite().  Therefore use nonseekable_open() and, redundantly, set
file_operations.llseek to no_llseek to remove any doubt whether the BKL-
grabbing default_llseek handler is used.

Although all this is legacy code which should be left in peace until it
is eventually removed (as it is superseded by firewire-core's
<linux/firewire-cdev.h> ABI), this change seems still worth doing to
further minimize the presence of BKL usage in the kernel.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/ieee1394/dv1394.c

@@ -1824,7 +1824,7 @@ static int dv1394_open(struct inode *inode, struct file *file)
 	       "and will not be available in the new firewire driver stack. "
 	       "Try libraw1394 based programs instead.\n", current->comm);
 
-	return 0;
+	return nonseekable_open(inode, file);
 }
 
 
@@ -2164,6 +2164,7 @@ static const struct file_operations dv1394_fops=
 	.read =		dv1394_read,
 	.release =	dv1394_release,
 	.fasync =	dv1394_fasync,
+	.llseek =	no_llseek,
 };
 
 

drivers/ieee1394/raw1394.c

@@ -2834,7 +2834,7 @@ static int raw1394_open(struct inode *inode, struct file *file)
 
 	file->private_data = fi;
 
-	return 0;
+	return nonseekable_open(inode, file);
 }
 
 static int raw1394_release(struct inode *inode, struct file *file)
@@ -3035,6 +3035,7 @@ static const struct file_operations raw1394_fops = {
 	.poll = raw1394_poll,
 	.open = raw1394_open,
 	.release = raw1394_release,
+	.llseek = no_llseek,
 };
 
 static int __init init_raw1394(void)

drivers/ieee1394/video1394.c

@@ -1239,7 +1239,7 @@ static int video1394_open(struct inode *inode, struct file *file)
 	ctx->current_ctx = NULL;
 	file->private_data = ctx;
 
-	return 0;
+	return nonseekable_open(inode, file);
 }
 
 static int video1394_release(struct inode *inode, struct file *file)
@@ -1287,7 +1287,8 @@ static const struct file_operations video1394_fops=
 	.poll =		video1394_poll,
 	.mmap =		video1394_mmap,
 	.open =		video1394_open,
-	.release =	video1394_release
+	.release =	video1394_release,
+	.llseek =	no_llseek,
 };
 
 /*** HOTPLUG STUFF **********************************************************/