V4L/DVB (9912): em28xx: fix/improve em28xx locking schema

Changes/fixes on em28xx dev->lock:

- em28xx_init_dev() were unlocking without a previous lock;

- some read ioctls need to lock after the removal of KBL, since a write
  may be happening at the same time an ioctl is reading;

- keep the device locked during all device initialization;

- lock/unlock while reading/writing registers.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 43 insertions, 12 deletions

diff --git a/drivers/media/video/em28xx/em28xx-video.c b/drivers/media/video/em28xx/em28xx-video.c
index 1681af192b02..de2d2fdbe6a4 100644
--- a/drivers/media/video/em28xx/em28xx-video.c
+++ b/drivers/media/video/em28xx/em28xx-video.c
@@ -784,10 +784,10 @@ static int vidioc_s_fmt_vid_cap(struct file *file, void *priv,
         if (rc < 0)
                 return rc;
 
-        vidioc_try_fmt_vid_cap(file, priv, f);
-
         mutex_lock(&dev->lock);
 
+        vidioc_try_fmt_vid_cap(file, priv, f);
+
         if (videobuf_queue_is_busy(&fh->vb_vidq)) {
                 em28xx_errdev("%s queue busy\n", __func__);
                 rc = -EBUSY;
@@ -828,15 +828,12 @@ static int vidioc_s_std(struct file *file, void *priv, v4l2_std_id * norm)
 
         mutex_lock(&dev->lock);
         dev->norm = *norm;
-        mutex_unlock(&dev->lock);
 
         /* Adjusts width/height, if needed */
         f.fmt.pix.width = dev->width;
         f.fmt.pix.height = dev->height;
         vidioc_try_fmt_vid_cap(file, priv, &f);
 
-        mutex_lock(&dev->lock);
-
         /* set new image size */
         dev->width = f.fmt.pix.width;
         dev->height = f.fmt.pix.height;
@@ -966,11 +963,15 @@ static int vidioc_s_audio(struct file *file, void *priv, struct v4l2_audio *a)
         struct em28xx_fh   *fh  = priv;
         struct em28xx      *dev = fh->dev;
 
+        mutex_lock(&dev->lock);
+
         dev->ctl_ainput = INPUT(a->index)->amux;
         dev->ctl_aoutput = INPUT(a->index)->aout;
 
         if (!dev->ctl_aoutput)
                 dev->ctl_aoutput = EM28XX_AOUT_MASTER;
+
+        mutex_unlock(&dev->lock);
         return 0;
 }
 
@@ -1019,6 +1020,7 @@ static int vidioc_g_ctrl(struct file *file, void *priv,
         rc = check_dev(dev);
         if (rc < 0)
                 return rc;
+
         mutex_lock(&dev->lock);
 
         if (!dev->board.has_msp34xx)
@@ -1129,8 +1131,10 @@ static int vidioc_g_frequency(struct file *file, void *priv,
         struct em28xx_fh      *fh  = priv;
         struct em28xx         *dev = fh->dev;
 
+        mutex_lock(&dev->lock);
         f->type = fh->radio ? V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV;
         f->frequency = dev->ctl_freq;
+        mutex_unlock(&dev->lock);
 
         return 0;
 }
@@ -1160,6 +1164,7 @@ static int vidioc_s_frequency(struct file *file, void *priv,
         em28xx_i2c_call_clients(dev, VIDIOC_S_FREQUENCY, f);
 
         mutex_unlock(&dev->lock);
+
         return 0;
 }
 
@@ -1187,15 +1192,20 @@ static int vidioc_g_register(struct file *file, void *priv,
                 return -EINVAL;
 
         if (em28xx_reg_len(reg->reg) == 1) {
+                mutex_lock(&dev->lock);
                 ret = em28xx_read_reg(dev, reg->reg);
+                mutex_unlock(&dev->lock);
+
                 if (ret < 0)
                         return ret;
 
                 reg->val = ret;
         } else {
                 __le64 val = 0;
+                mutex_lock(&dev->lock);
                 ret = em28xx_read_reg_req_len(dev, USB_REQ_GET_STATUS,
                                                    reg->reg, (char *)&val, 2);
+                mutex_unlock(&dev->lock);
                 if (ret < 0)
                         return ret;
 
@@ -1211,11 +1221,16 @@ static int vidioc_s_register(struct file *file, void *priv,
         struct em28xx_fh      *fh  = priv;
         struct em28xx         *dev = fh->dev;
         __le64 buf;
+        int    rc;
 
         buf = cpu_to_le64(reg->val);
 
-        return em28xx_write_regs(dev, reg->reg, (char *)&buf,
-                                 em28xx_reg_len(reg->reg));
+        mutex_lock(&dev->lock);
+        rc = em28xx_write_regs(dev, reg->reg, (char *)&buf,
+                               em28xx_reg_len(reg->reg));
+        mutex_unlock(&dev->lock);
+
+        return rc;
 }
 #endif
 
@@ -1254,12 +1269,15 @@ static int vidioc_streamon(struct file *file, void *priv,
 
         mutex_lock(&dev->lock);
         rc = res_get(fh);
-        mutex_unlock(&dev->lock);
 
         if (unlikely(rc < 0))
                 return rc;
 
-        return (videobuf_streamon(&fh->vb_vidq));
+        rc = videobuf_streamon(&fh->vb_vidq);
+
+        mutex_unlock(&dev->lock);
+
+        return rc;
 }
 
 static int vidioc_streamoff(struct file *file, void *priv,
@@ -1278,9 +1296,11 @@ static int vidioc_streamoff(struct file *file, void *priv,
         if (type != fh->type)
                 return -EINVAL;
 
-        videobuf_streamoff(&fh->vb_vidq);
         mutex_lock(&dev->lock);
+
+        videobuf_streamoff(&fh->vb_vidq);
         res_free(fh);
+
         mutex_unlock(&dev->lock);
 
         return 0;
@@ -1465,7 +1485,10 @@ static int radio_g_tuner(struct file *file, void *priv,
         strcpy(t->name, "Radio");
         t->type = V4L2_TUNER_RADIO;
 
+        mutex_lock(&dev->lock);
         em28xx_i2c_call_clients(dev, VIDIOC_G_TUNER, t);
+        mutex_unlock(&dev->lock);
+
         return 0;
 }
 
@@ -1497,7 +1520,9 @@ static int radio_s_tuner(struct file *file, void *priv,
         if (0 != t->index)
                 return -EINVAL;
 
+        mutex_lock(&dev->lock);
         em28xx_i2c_call_clients(dev, VIDIOC_S_TUNER, t);
+        mutex_unlock(&dev->lock);
 
         return 0;
 }
@@ -1561,6 +1586,7 @@ static int em28xx_v4l2_open(struct inode *inode, struct file *filp)
                 }
         }
         mutex_unlock(&em28xx_devlist_mutex);
+
         if (NULL == dev)
                 return -ENODEV;
 
@@ -2036,7 +2062,6 @@ static int em28xx_init_dev(struct em28xx **devhandle, struct usb_device *udev,
         unsigned int maxh, maxw;
 
         dev->udev = udev;
-        mutex_init(&dev->lock);
         mutex_init(&dev->ctrl_urb_lock);
         spin_lock_init(&dev->slock);
         init_waitqueue_head(&dev->open);
@@ -2151,7 +2176,6 @@ static int em28xx_init_dev(struct em28xx **devhandle, struct usb_device *udev,
         return 0;
 
 fail_reg_devices:
-        mutex_unlock(&dev->lock);
         return retval;
 }
 
@@ -2343,6 +2367,8 @@ static int em28xx_usb_probe(struct usb_interface *interface,
                 dev->model = card[nr];
 
         /* allocate device struct */
+        mutex_init(&dev->lock);
+        mutex_lock(&dev->lock);
         retval = em28xx_init_dev(&dev, udev, nr);
         if (retval) {
                 em28xx_devused &= ~(1<<dev->devno);
@@ -2356,6 +2382,11 @@ static int em28xx_usb_probe(struct usb_interface *interface,
 
         request_modules(dev);
 
+        /* Should be the last thing to do, to avoid newer udev's to
+           open the device before fully initializing it
+         */
+        mutex_unlock(&dev->lock);
+
         return 0;
 }