[media] v4l: kill the BKL

All of the hard problems for BKL removal appear to be solved in the
v4l-dvb/master tree. This removes the BKL from the various open
functions that do not need it, or only use it to protect an
open count.

The zoran driver is nontrivial in this regard, so I introduce
a new mutex that locks both the open/release and the ioctl
functions. Someone with access to the hardware can probably
improve that by using the existing lock in all cases.

Finally, all drivers that still use the locked version of the
ioctl function now get called under a new mutex instead of
the BKL.

Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/Kconfig

···
 
 config VIDEO_DEV
 	tristate "Video For Linux"
-	depends on BKL # used in many drivers for ioctl handling, need to kill
 	---help---
 	  V4L core support for video capture and overlay devices, webcams and
 	  AM/FM radio cards.

drivers/media/video/cx231xx/cx231xx-417.c

···
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/firmware.h>
-#include <linux/smp_lock.h>
 #include <linux/vmalloc.h>
 #include <media/v4l2-common.h>
 #include <media/v4l2-ioctl.h>
···
 			dev = h;
 	}
 
-	if (dev == NULL) {
-		unlock_kernel();
+	if (dev == NULL)
 		return -ENODEV;
-	}
+
 	mutex_lock(&dev->lock);
 
 	/* allocate + initialize per filehandle data */

drivers/media/video/cx23885/cx23885-417.c

···
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/firmware.h>
-#include <linux/smp_lock.h>
 #include <linux/slab.h>
 #include <media/v4l2-common.h>
 #include <media/v4l2-ioctl.h>
···
 
 	/* allocate + initialize per filehandle data */
 	fh = kzalloc(sizeof(*fh), GFP_KERNEL);
-	if (NULL == fh) {
-		unlock_kernel();
+	if (!fh)
 		return -ENOMEM;
-	}
-
-	lock_kernel();
 
 	file->private_data = fh;
 	fh->dev      = dev;
···
 			    V4L2_FIELD_INTERLACED,
 			    sizeof(struct cx23885_buffer),
 			    fh, NULL);
-	unlock_kernel();
-
 	return 0;
 }
 

drivers/media/video/cx23885/cx23885-video.c

···
 #include <linux/kmod.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/kthread.h>
···
 	if (NULL == fh)
 		return -ENOMEM;
 
-	lock_kernel();
-
 	file->private_data = fh;
 	fh->dev      = dev;
 	fh->radio    = radio;
···
 			    fh, NULL);
 
 	dprintk(1, "post videobuf_queue_init()\n");
-
-	unlock_kernel();
 
 	return 0;
 }

drivers/media/video/se401.c

···
 #include <linux/init.h>
 #include <linux/vmalloc.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/pagemap.h>
 #include <linux/usb.h>
 #include "se401.h"
···
 	struct usb_se401 *se401 = (struct usb_se401 *)dev;
 	int err = 0;
 
-	lock_kernel();
+	mutex_lock(&se401->lock);
 	if (se401->user) {
-		unlock_kernel();
+		mutex_unlock(&se401->lock);
 		return -EBUSY;
 	}
 	se401->fbuf = rvmalloc(se401->maxframesize * SE401_NUMFRAMES);
···
 	else
 		err = -ENOMEM;
 	se401->user = !err;
-	unlock_kernel();
+	mutex_unlock(&se401->lock);
 
 	return err;
 }

drivers/media/video/stk-webcam.c

···
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 
 #include <linux/usb.h>
 #include <linux/mm.h>
···
 	vdev = video_devdata(fp);
 	dev = vdev_to_camera(vdev);
 
-	lock_kernel();
 	if (dev == NULL || !is_present(dev)) {
-		unlock_kernel();
 		return -ENXIO;
 	}
 	fp->private_data = dev;
 	usb_autopm_get_interface(dev->interface);
-	unlock_kernel();
 
 	return 0;
 }

drivers/media/video/tlg2300/pd-main.c

···
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/firmware.h>
-#include <linux/smp_lock.h>
 
 #include "vendorcmds.h"
 #include "pd-common.h"
···
 	/*unregister v4l2 device */
 	v4l2_device_unregister(&pd->v4l2_dev);
 
-	lock_kernel();
-	{
-		pd_dvb_usb_device_exit(pd);
-		poseidon_fm_exit(pd);
+	pd_dvb_usb_device_exit(pd);
+	poseidon_fm_exit(pd);
 
-		poseidon_audio_free(pd);
-		pd_video_exit(pd);
-	}
-	unlock_kernel();
+	poseidon_audio_free(pd);
+	pd_video_exit(pd);
 
 	usb_set_intfdata(interface, NULL);
 	kref_put(&pd->kref, poseidon_delete);

drivers/media/video/usbvideo/vicam.c

···
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/mutex.h>
 #include <linux/firmware.h>
 #include <linux/ihex.h>
···
 		return -EINVAL;
 	}
 
-	/* the videodev_lock held above us protects us from
-	 * simultaneous opens...for now. we probably shouldn't
-	 * rely on this fact forever.
+	/* cam_lock/open_count protects us from simultaneous opens
+	 * ... for now. we probably shouldn't rely on this fact forever.
 	 */
 
-	lock_kernel();
+	mutex_lock(&cam->cam_lock);
 	if (cam->open_count > 0) {
 		printk(KERN_INFO
 		       "vicam_open called on already opened camera");
-		unlock_kernel();
+		mutex_unlock(&cam->cam_lock);
 		return -EBUSY;
 	}
 
 	cam->raw_image = kmalloc(VICAM_MAX_READ_SIZE, GFP_KERNEL);
 	if (!cam->raw_image) {
-		unlock_kernel();
+		mutex_unlock(&cam->cam_lock);
 		return -ENOMEM;
 	}
 
 	cam->framebuf = rvmalloc(VICAM_MAX_FRAME_SIZE * VICAM_FRAMES);
 	if (!cam->framebuf) {
 		kfree(cam->raw_image);
-		unlock_kernel();
+		mutex_unlock(&cam->cam_lock);
 		return -ENOMEM;
 	}
 
···
 	if (!cam->cntrlbuf) {
 		kfree(cam->raw_image);
 		rvfree(cam->framebuf, VICAM_MAX_FRAME_SIZE * VICAM_FRAMES);
-		unlock_kernel();
+		mutex_unlock(&cam->cam_lock);
 		return -ENOMEM;
 	}
+
+	cam->needsDummyRead = 1;
+	cam->open_count++;
+
+	file->private_data = cam;
+	mutex_unlock(&cam->cam_lock);
+
 
 	// First upload firmware, then turn the camera on
 
···
 	}
 
 	set_camera_power(cam, 1);
-
-	cam->needsDummyRead = 1;
-	cam->open_count++;
-
-	file->private_data = cam;
-	unlock_kernel();
 
 	return 0;
 }

drivers/media/video/v4l2-dev.c

···
 #include <linux/init.h>
 #include <linux/kmod.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <asm/uaccess.h>
 #include <asm/system.h>
 
···
 			mutex_unlock(vdev->lock);
 	} else if (vdev->fops->ioctl) {
 		/* TODO: convert all drivers to unlocked_ioctl */
-		lock_kernel();
+		static DEFINE_MUTEX(v4l2_ioctl_mutex);
+
+		mutex_lock(&v4l2_ioctl_mutex);
 		if (video_is_registered(vdev))
 			ret = vdev->fops->ioctl(filp, cmd, arg);
-		unlock_kernel();
+		mutex_unlock(&v4l2_ioctl_mutex);
 	} else
 		ret = -ENOTTY;
 

drivers/media/video/zoran/zoran.h

···
 	struct videocodec *vfe;	/* video front end */
 
 	struct mutex resource_lock;	/* prevent evil stuff */
+	struct mutex other_lock;	/* please merge with above */
 
 	u8 initialized;		/* flag if zoran has been correctly initialized */
 	int user;		/* number of current users */

drivers/media/video/zoran/zoran_card.c

···
 	snprintf(ZR_DEVNAME(zr), sizeof(ZR_DEVNAME(zr)), "MJPEG[%u]", zr->id);
 	spin_lock_init(&zr->spinlock);
 	mutex_init(&zr->resource_lock);
+	mutex_init(&zr->other_lock);
 	if (pci_enable_device(pdev))
 		goto zr_unreg;
 	pci_read_config_byte(zr->pci_dev, PCI_CLASS_REVISION, &zr->revision);

drivers/media/video/zoran/zoran_driver.c

···
 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/pci.h>
 #include <linux/vmalloc.h>
 #include <linux/wait.h>
···
 	dprintk(2, KERN_INFO "%s: %s(%s, pid=[%d]), users(-)=%d\n",
 		ZR_DEVNAME(zr), __func__, current->comm, task_pid_nr(current), zr->user + 1);
 
-	lock_kernel();
+	mutex_lock(&zr->other_lock);
 
 	if (zr->user >= 2048) {
 		dprintk(1, KERN_ERR "%s: too many users (%d) on device\n",
···
 	file->private_data = fh;
 	fh->zr = zr;
 	zoran_open_init_session(fh);
-	unlock_kernel();
+	mutex_unlock(&zr->other_lock);
 
 	return 0;
 
 fail_fh:
 	kfree(fh);
 fail_unlock:
-	unlock_kernel();
+	mutex_unlock(&zr->other_lock);
 
 	dprintk(2, KERN_INFO "%s: open failed (%d), users(-)=%d\n",
 		ZR_DEVNAME(zr), res, zr->user);
···
 
 	/* kernel locks (fs/device.c), so don't do that ourselves
 	 * (prevents deadlocks) */
-	/*mutex_lock(&zr->resource_lock);*/
+	mutex_lock(&zr->other_lock);
 
 	zoran_close_end_session(fh);
 
···
 			encoder_call(zr, video, s_routing, 2, 0, 0);
 		}
 	}
+	mutex_unlock(&zr->other_lock);
 
 	file->private_data = NULL;
 	kfree(fh->overlay_mask);
···
 #endif
 };
 
+/* please use zr->resource_lock consistently and kill this wrapper */
+static long zoran_ioctl(struct file *file, unsigned int cmd,
+			unsigned long arg)
+{
+	struct zoran_fh *fh = file->private_data;
+	struct zoran *zr = fh->zr;
+	int ret;
+
+	mutex_lock(&zr->other_lock);
+	ret = video_ioctl2(file, cmd, arg);
+	mutex_unlock(&zr->other_lock);
+
+	return ret;
+}
+
 static const struct v4l2_file_operations zoran_fops = {
 	.owner = THIS_MODULE,
 	.open = zoran_open,
 	.release = zoran_close,
-	.ioctl = video_ioctl2,
+	.unlocked_ioctl = zoran_ioctl,
 	.read = zoran_read,
 	.write = zoran_write,
 	.mmap = zoran_mmap,