V4L/DVB: bttv: fix driver lock and remove explicit calls to BKL

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

1 files changed, 143 insertions, 58 deletions

diff --git a/drivers/media/video/bt8xx/bttv-driver.c b/drivers/media/video/bt8xx/bttv-driver.c
index d74dfa6d1a55..056888cbc8e7 100644
--- a/drivers/media/video/bt8xx/bttv-driver.c
+++ b/drivers/media/video/bt8xx/bttv-driver.c
@@ -1859,21 +1859,25 @@ static int bttv_s_std(struct file *file, void *priv, v4l2_std_id *id)
         unsigned int i;
         int err;
 
+        mutex_lock(&btv->lock);
         err = v4l2_prio_check(&btv->prio, fh->prio);
-        if (0 != err)
-                return err;
+        if (err)
+                goto err;
 
         for (i = 0; i < BTTV_TVNORMS; i++)
                 if (*id & bttv_tvnorms[i].v4l2_id)
                         break;
-        if (i == BTTV_TVNORMS)
-                return -EINVAL;
+        if (i == BTTV_TVNORMS) {
+                err = -EINVAL;
+                goto err;
+        }
 
-        mutex_lock(&btv->lock);
         set_tvnorm(btv, i);
+
+err:
         mutex_unlock(&btv->lock);
 
-        return 0;
+        return err;
 }
 
 static int bttv_querystd(struct file *file, void *f, v4l2_std_id *id)
@@ -1893,10 +1897,13 @@ static int bttv_enum_input(struct file *file, void *priv,
 {
         struct bttv_fh *fh = priv;
         struct bttv *btv = fh->btv;
-        int n;
+        int rc = 0;
 
-        if (i->index >= bttv_tvcards[btv->c.type].video_inputs)
-                return -EINVAL;
+        mutex_lock(&btv->lock);
+        if (i->index >= bttv_tvcards[btv->c.type].video_inputs) {
+                rc = -EINVAL;
+                goto err;
+        }
 
         i->type     = V4L2_INPUT_TYPE_CAMERA;
         i->audioset = 1;
@@ -1919,10 +1926,12 @@ static int bttv_enum_input(struct file *file, void *priv,
                         i->status |= V4L2_IN_ST_NO_H_LOCK;
         }
 
-        for (n = 0; n < BTTV_TVNORMS; n++)
-                i->std |= bttv_tvnorms[n].v4l2_id;
+        i->std = BTTV_NORMS;
 
-        return 0;
+err:
+        mutex_unlock(&btv->lock);
+
+        return rc;
 }
 
 static int bttv_g_input(struct file *file, void *priv, unsigned int *i)
@@ -1930,7 +1939,10 @@ static int bttv_g_input(struct file *file, void *priv, unsigned int *i)
         struct bttv_fh *fh = priv;
         struct bttv *btv = fh->btv;
 
+        mutex_lock(&btv->lock);
         *i = btv->input;
+        mutex_unlock(&btv->lock);
+
         return 0;
 }
 
@@ -1941,15 +1953,19 @@ static int bttv_s_input(struct file *file, void *priv, unsigned int i)
 
         int err;
 
+        mutex_lock(&btv->lock);
         err = v4l2_prio_check(&btv->prio, fh->prio);
-        if (0 != err)
-                return err;
+        if (unlikely(err))
+                goto err;
 
-        if (i > bttv_tvcards[btv->c.type].video_inputs)
-                return -EINVAL;
+        if (i > bttv_tvcards[btv->c.type].video_inputs) {
+                err = -EINVAL;
+                goto err;
+        }
 
-        mutex_lock(&btv->lock);
         set_input(btv, i, btv->tvnorm);
+
+err:
         mutex_unlock(&btv->lock);
         return 0;
 }
@@ -1961,22 +1977,25 @@ static int bttv_s_tuner(struct file *file, void *priv,
         struct bttv *btv = fh->btv;
         int err;
 
-        err = v4l2_prio_check(&btv->prio, fh->prio);
-        if (0 != err)
-                return err;
-
-        if (btv->tuner_type == TUNER_ABSENT)
-                return -EINVAL;
-
-        if (0 != t->index)
+        if (unlikely(0 != t->index))
                 return -EINVAL;
 
         mutex_lock(&btv->lock);
+        if (unlikely(btv->tuner_type == TUNER_ABSENT)) {
+                err = -EINVAL;
+                goto err;
+        }
+
+        err = v4l2_prio_check(&btv->prio, fh->prio);
+        if (unlikely(err))
+                goto err;
+
         bttv_call_all(btv, tuner, s_tuner, t);
 
         if (btv->audio_mode_gpio)
                 btv->audio_mode_gpio(btv, t, 1);
 
+err:
         mutex_unlock(&btv->lock);
 
         return 0;
@@ -1988,8 +2007,10 @@ static int bttv_g_frequency(struct file *file, void *priv,
         struct bttv_fh *fh  = priv;
         struct bttv *btv = fh->btv;
 
+        mutex_lock(&btv->lock);
         f->type = btv->radio_user ? V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV;
         f->frequency = btv->freq;
+        mutex_unlock(&btv->lock);
 
         return 0;
 }
@@ -2001,21 +2022,26 @@ static int bttv_s_frequency(struct file *file, void *priv,
         struct bttv *btv = fh->btv;
         int err;
 
-        err = v4l2_prio_check(&btv->prio, fh->prio);
-        if (0 != err)
-                return err;
-
         if (unlikely(f->tuner != 0))
                 return -EINVAL;
-        if (unlikely(f->type != (btv->radio_user
-                ? V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV)))
-                return -EINVAL;
+
         mutex_lock(&btv->lock);
+        err = v4l2_prio_check(&btv->prio, fh->prio);
+        if (unlikely(err))
+                goto err;
+
+        if (unlikely(f->type != (btv->radio_user
+                ? V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV))) {
+                err = -EINVAL;
+                goto err;
+        }
         btv->freq = f->frequency;
         bttv_call_all(btv, tuner, s_frequency, f);
         if (btv->has_matchbox && btv->radio_user)
                 tea5757_set_freq(btv, btv->freq);
+err:
         mutex_unlock(&btv->lock);
+
         return 0;
 }
 
@@ -2257,7 +2283,9 @@ verify_window_lock		(struct bttv_fh *               fh,
         if (V4L2_FIELD_ANY == field) {
                 __s32 height2;
 
+                mutex_lock(&fh->btv->lock);
                 height2 = fh->btv->crop[!!fh->do_crop].rect.height >> 1;
+                mutex_unlock(&fh->btv->lock);
                 field = (win->w.height > height2)
                         ? V4L2_FIELD_INTERLACED
                         : V4L2_FIELD_TOP;
@@ -2332,6 +2360,8 @@ static int setup_window_lock(struct bttv_fh *fh, struct bttv *btv,
                         return -EFAULT;
                 }
         }
+
+        mutex_lock(&fh->cap.vb_lock);
         /* clip against screen */
         if (NULL != btv->fbuf.base)
                 n = btcx_screen_clips(btv->fbuf.fmt.width, btv->fbuf.fmt.height,
@@ -2354,7 +2384,6 @@ static int setup_window_lock(struct bttv_fh *fh, struct bttv *btv,
                 BUG();
         }
 
-        mutex_lock(&fh->cap.vb_lock);
         kfree(fh->ov.clips);
         fh->ov.clips    = clips;
         fh->ov.nclips   = n;
@@ -2362,6 +2391,14 @@ static int setup_window_lock(struct bttv_fh *fh, struct bttv *btv,
         fh->ov.w        = win->w;
         fh->ov.field    = win->field;
         fh->ov.setup_ok = 1;
+
+        /*
+         * FIXME: btv is protected by btv->lock mutex, while btv->init
+         *        is protected by fh->cap.vb_lock. This seems to open the
+         *        possibility for some race situations. Maybe the better would
+         *        be to unify those locks or to use another way to store the
+         *        init values that will be consumed by videobuf callbacks
+         */
         btv->init.ov.w.width   = win->w.width;
         btv->init.ov.w.height  = win->w.height;
         btv->init.ov.field     = win->field;
@@ -2490,7 +2527,9 @@ static int bttv_try_fmt_vid_cap(struct file *file, void *priv,
         if (V4L2_FIELD_ANY == field) {
                 __s32 height2;
 
+                mutex_lock(&btv->lock);
                 height2 = btv->crop[!!fh->do_crop].rect.height >> 1;
+                mutex_unlock(&btv->lock);
                 field = (f->fmt.pix.height > height2)
                         ? V4L2_FIELD_INTERLACED
                         : V4L2_FIELD_BOTTOM;
@@ -2651,11 +2690,15 @@ static int bttv_querycap(struct file *file, void  *priv,
                 V4L2_CAP_VBI_CAPTURE |
                 V4L2_CAP_READWRITE |
                 V4L2_CAP_STREAMING;
-        if (btv->has_saa6588)
-                cap->capabilities |= V4L2_CAP_RDS_CAPTURE;
         if (no_overlay <= 0)
                 cap->capabilities |= V4L2_CAP_VIDEO_OVERLAY;
 
+        /*
+         * No need to lock here: those vars are initialized during board
+         * probe and remains untouched during the rest of the driver lifecycle
+         */
+        if (btv->has_saa6588)
+                cap->capabilities |= V4L2_CAP_RDS_CAPTURE;
         if (btv->tuner_type != TUNER_ABSENT)
                 cap->capabilities |= V4L2_CAP_TUNER;
         return 0;
@@ -2730,16 +2773,22 @@ static int bttv_overlay(struct file *file, void *f, unsigned int on)
         struct bttv_fh *fh = f;
         struct bttv *btv = fh->btv;
         struct bttv_buffer *new;
-        int retval;
+        int retval = 0;
 
         if (on) {
+                mutex_lock(&fh->cap.vb_lock);
                 /* verify args */
-                if (NULL == btv->fbuf.base)
+                if (unlikely(!btv->fbuf.base)) {
+                        mutex_unlock(&fh->cap.vb_lock);
                         return -EINVAL;
-                if (!fh->ov.setup_ok) {
+                }
+                if (unlikely(!fh->ov.setup_ok)) {
                         dprintk("bttv%d: overlay: !setup_ok\n", btv->c.nr);
-                        return -EINVAL;
+                        retval = -EINVAL;
                 }
+                if (retval)
+                        return retval;
+                mutex_unlock(&fh->cap.vb_lock);
         }
 
         if (!check_alloc_btres_lock(btv, fh, RESOURCE_OVERLAY))
@@ -2907,6 +2956,7 @@ static int bttv_queryctrl(struct file *file, void *priv,
              c->id >= V4L2_CID_PRIVATE_LASTP1))
                 return -EINVAL;
 
+        mutex_lock(&btv->lock);
         if (!btv->volume_gpio && (c->id == V4L2_CID_AUDIO_VOLUME))
                 *c = no_ctl;
         else {
@@ -2914,6 +2964,7 @@ static int bttv_queryctrl(struct file *file, void *priv,
 
                 *c = (NULL != ctrl) ? *ctrl : no_ctl;
         }
+        mutex_unlock(&btv->lock);
 
         return 0;
 }
@@ -2924,8 +2975,11 @@ static int bttv_g_parm(struct file *file, void *f,
         struct bttv_fh *fh = f;
         struct bttv *btv = fh->btv;
 
+        mutex_lock(&btv->lock);
         v4l2_video_std_frame_period(bttv_tvnorms[btv->tvnorm].v4l2_id,
                                     &parm->parm.capture.timeperframe);
+        mutex_unlock(&btv->lock);
+
         return 0;
 }
 
@@ -2961,7 +3015,9 @@ static int bttv_g_priority(struct file *file, void *f, enum v4l2_priority *p)
         struct bttv_fh *fh = f;
         struct bttv *btv = fh->btv;
 
+        mutex_lock(&btv->lock);
         *p = v4l2_prio_max(&btv->prio);
+        mutex_unlock(&btv->lock);
 
         return 0;
 }
@@ -2971,8 +3027,13 @@ static int bttv_s_priority(struct file *file, void *f,
 {
         struct bttv_fh *fh = f;
         struct bttv *btv = fh->btv;
+        int     rc;
+
+        mutex_lock(&btv->lock);
+        rc = v4l2_prio_change(&btv->prio, &fh->prio, prio);
+        mutex_unlock(&btv->lock);
 
-        return v4l2_prio_change(&btv->prio, &fh->prio, prio);
+        return rc;
 }
 
 static int bttv_cropcap(struct file *file, void *priv,
@@ -2985,7 +3046,9 @@ static int bttv_cropcap(struct file *file, void *priv,
             cap->type != V4L2_BUF_TYPE_VIDEO_OVERLAY)
                 return -EINVAL;
 
+        mutex_lock(&btv->lock);
         *cap = bttv_tvnorms[btv->tvnorm].cropcap;
+        mutex_unlock(&btv->lock);
 
         return 0;
 }
@@ -3003,7 +3066,9 @@ static int bttv_g_crop(struct file *file, void *f, struct v4l2_crop *crop)
            inconsistent with fh->width or fh->height and apps
            do not expect a change here. */
 
+        mutex_lock(&btv->lock);
         crop->c = btv->crop[!!fh->do_crop].rect;
+        mutex_unlock(&btv->lock);
 
         return 0;
 }
@@ -3024,14 +3089,15 @@ static int bttv_s_crop(struct file *file, void *f, struct v4l2_crop *crop)
             crop->type != V4L2_BUF_TYPE_VIDEO_OVERLAY)
                 return -EINVAL;
 
-        retval = v4l2_prio_check(&btv->prio, fh->prio);
-        if (0 != retval)
-                return retval;
-
         /* Make sure tvnorm, vbi_end and the current cropping
            parameters remain consistent until we're done. Note
            read() may change vbi_end in check_alloc_btres_lock(). */
         mutex_lock(&btv->lock);
+        retval = v4l2_prio_check(&btv->prio, fh->prio);
+        if (0 != retval) {
+                mutex_unlock(&btv->lock);
+                return retval;
+        }
 
         retval = -EBUSY;
 
@@ -3219,21 +3285,32 @@ static int bttv_open(struct file *file)
                 return -ENODEV;
         }
 
-        lock_kernel();
-
         dprintk(KERN_DEBUG "bttv%d: open called (type=%s)\n",
                 btv->c.nr,v4l2_type_names[type]);
 
         /* allocate per filehandle data */
-        fh = kmalloc(sizeof(*fh),GFP_KERNEL);
-        if (NULL == fh) {
-                unlock_kernel();
+        fh = kmalloc(sizeof(*fh), GFP_KERNEL);
+        if (unlikely(!fh))
                 return -ENOMEM;
-        }
         file->private_data = fh;
+
+        /*
+         * btv is protected by btv->lock mutex, while btv->init and other
+         * streaming vars are protected by fh->cap.vb_lock. We need to take
+         * care of both locks to avoid troubles. However, vb_lock is used also
+         * inside videobuf, without calling buf->lock. So, it is a very bad
+         * idea to hold both locks at the same time.
+         * Let's first copy btv->init at fh, holding cap.vb_lock, and then work
+         * with the rest of init, holding btv->lock.
+         */
+        mutex_lock(&fh->cap.vb_lock);
         *fh = btv->init;
+        mutex_unlock(&fh->cap.vb_lock);
+
         fh->type = type;
         fh->ov.setup_ok = 0;
+
+        mutex_lock(&btv->lock);
         v4l2_prio_open(&btv->prio, &fh->prio);
 
         videobuf_queue_sg_init(&fh->cap, &bttv_video_qops,
@@ -3270,7 +3347,7 @@ static int bttv_open(struct file *file)
         bttv_vbi_fmt_reset(&fh->vbi_fmt, btv->tvnorm);
 
         bttv_field_count(btv);
-        unlock_kernel();
+        mutex_unlock(&btv->lock);
         return 0;
 }
 
@@ -3279,6 +3356,7 @@ static int bttv_release(struct file *file)
         struct bttv_fh *fh = file->private_data;
         struct bttv *btv = fh->btv;
 
+        mutex_lock(&btv->lock);
         /* turn off overlay */
         if (check_btres(fh, RESOURCE_OVERLAY))
                 bttv_switch_overlay(btv,fh,NULL);
@@ -3303,8 +3381,15 @@ static int bttv_release(struct file *file)
         }
 
         /* free stuff */
+
+        /*
+         * videobuf uses cap.vb_lock - we should avoid holding btv->lock,
+         * otherwise we may have dead lock conditions
+         */
+        mutex_unlock(&btv->lock);
         videobuf_mmap_free(&fh->cap);
         videobuf_mmap_free(&fh->vbi);
+        mutex_lock(&btv->lock);
         v4l2_prio_close(&btv->prio, fh->prio);
         file->private_data = NULL;
         kfree(fh);
@@ -3314,6 +3399,7 @@ static int bttv_release(struct file *file)
 
         if (!btv->users)
                 audio_mute(btv, 1);
+        mutex_unlock(&btv->lock);
 
         return 0;
 }
@@ -3410,21 +3496,19 @@ static int radio_open(struct file *file)
 
         dprintk("bttv: open dev=%s\n", video_device_node_name(vdev));
 
-        lock_kernel();
-
         dprintk("bttv%d: open called (radio)\n",btv->c.nr);
 
         /* allocate per filehandle data */
         fh = kmalloc(sizeof(*fh), GFP_KERNEL);
-        if (NULL == fh) {
-                unlock_kernel();
+        if (unlikely(!fh))
                 return -ENOMEM;
-        }
         file->private_data = fh;
+        mutex_lock(&fh->cap.vb_lock);
         *fh = btv->init;
-        v4l2_prio_open(&btv->prio, &fh->prio);
+        mutex_unlock(&fh->cap.vb_lock);
 
         mutex_lock(&btv->lock);
+        v4l2_prio_open(&btv->prio, &fh->prio);
 
         btv->radio_user++;
 
@@ -3432,7 +3516,6 @@ static int radio_open(struct file *file)
         audio_input(btv,TVAUDIO_INPUT_RADIO);
 
         mutex_unlock(&btv->lock);
-        unlock_kernel();
         return 0;
 }
 
@@ -3442,6 +3525,7 @@ static int radio_release(struct file *file)
         struct bttv *btv = fh->btv;
         struct rds_command cmd;
 
+        mutex_lock(&btv->lock);
         v4l2_prio_close(&btv->prio, fh->prio);
         file->private_data = NULL;
         kfree(fh);
@@ -3449,6 +3533,7 @@ static int radio_release(struct file *file)
         btv->radio_user--;
 
         bttv_call_all(btv, core, ioctl, RDS_CMD_CLOSE, &cmd);
+        mutex_unlock(&btv->lock);
 
         return 0;
 }