> PS.: The patch is based against the bkl_removal patches, at my linux-next tree:
>
>
http://git.kernel.org/?p=linux/kernel/git/mchehab/linux-next.git;a=commit;h=673eb9ff33...
>
> (I just created the bkl_removal branch, so, it may take some time for you to see at the kernel.org
> mirrors, but it is basically changeset 673eb9ff. You may also just apply it on the top of the master
> branch of my linux-next tree).
>
> ---
>
> [media] bttv: Fix locking issues due to BKL removal code
>
> The BKL removal patch added a condition where the code would try to use a non-initialized
> lock. While a patch just addressing the issue is possible, there are some other troubles,
> like to the presence of lock code at free_btres_lock(), called on some places with the lock
> already taken. It is possible to fix, but the better is to just use the core-assisted
> locking schema.
>
> This way, V4L2 core will serialize access to all ioctl's/open/close/mmap/read/poll
> operations, avoiding to have two processes accessing the hardware at the same time.
> Also, as there's just one lock, instead of 3, there's no risk of dead locks.
>
> Tested with bttv STB, Gateway P/N 6000699 (card 3, tuner 6).
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
>
> diff --git a/drivers/media/video/bt8xx/bttv-driver.c b/drivers/media/video/bt8xx/bttv-driver.c
> index a529619..25e1ca0 100644
> --- a/drivers/media/video/bt8xx/bttv-driver.c
> +++ b/drivers/media/video/bt8xx/bttv-driver.c
> @@ -854,7 +854,6 @@ int check_alloc_btres_lock(struct bttv *btv, struct bttv_fh *fh, int bit)
> xbits |= RESOURCE_VIDEO_READ | RESOURCE_VIDEO_STREAM;
>
> /* is it free? */
> - mutex_lock(&btv->lock);
> if (btv->resources & xbits) {
> /* no, someone else uses it */
> goto fail;
> @@ -884,11 +883,9 @@ int check_alloc_btres_lock(struct bttv *btv, struct bttv_fh *fh, int bit)
> /* it's free, grab it */
> fh->resources |= bit;
> btv->resources |= bit;
> - mutex_unlock(&btv->lock);
> return 1;
>
> fail:
> - mutex_unlock(&btv->lock);
> return 0;
> }
>
> @@ -940,7 +937,6 @@ void free_btres_lock(struct bttv *btv, struct bttv_fh *fh, int bits)
> /* trying to free ressources not allocated by us ... */
> printk("bttv: BUG! (btres)\n");
> }
> - mutex_lock(&btv->lock);
> fh->resources &= ~bits;
> btv->resources &= ~bits;
>
> @@ -951,8 +947,6 @@ void free_btres_lock(struct bttv *btv, struct bttv_fh *fh, int bits)
>
> if (0 == (bits & VBI_RESOURCES))
> disclaim_vbi_lines(btv);
> -
> - mutex_unlock(&btv->lock);
> }
>
> /* ----------------------------------------------------------------------- */
> @@ -1713,28 +1707,20 @@ static int bttv_prepare_buffer(struct videobuf_queue *q,struct bttv *btv,
>
> /* Make sure tvnorm and vbi_end remain consistent
> until we're done. */
> - mutex_lock(&btv->lock);
>
> norm = btv->tvnorm;
>
> /* In this mode capturing always starts at defrect.top
> (default VDELAY), ignoring cropping parameters. */
> if (btv->vbi_end > bttv_tvnorms[norm].cropcap.defrect.top) {
> - mutex_unlock(&btv->lock);
> return -EINVAL;
> }
>
> - mutex_unlock(&btv->lock);
> -
> c.rect = bttv_tvnorms[norm].cropcap.defrect;
> } else {
> - mutex_lock(&btv->lock);
> -
> norm = btv->tvnorm;
> c = btv->crop[!!fh->do_crop];
>
> - mutex_unlock(&btv->lock);
> -
> if (width < c.min_scaled_width ||
> width > c.max_scaled_width ||
> height < c.min_scaled_height)
> @@ -1858,7 +1844,6 @@ 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 (err)
> goto err;
> @@ -1874,7 +1859,6 @@ static int bttv_s_std(struct file *file, void *priv, v4l2_std_id *id)
> set_tvnorm(btv, i);
>
> err:
> - mutex_unlock(&btv->lock);
>
> return err;
> }
> @@ -1898,7 +1882,6 @@ static int bttv_enum_input(struct file *file, void *priv,
> struct bttv *btv = fh->btv;
> int rc = 0;
>
> - mutex_lock(&btv->lock);
> if (i->index >= bttv_tvcards[btv->c.type].video_inputs) {
> rc = -EINVAL;
> goto err;
> @@ -1928,7 +1911,6 @@ static int bttv_enum_input(struct file *file, void *priv,
> i->std = BTTV_NORMS;
>
> err:
> - mutex_unlock(&btv->lock);
>
> return rc;
> }
> @@ -1938,9 +1920,7 @@ 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;
> }
> @@ -1952,7 +1932,6 @@ 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 (unlikely(err))
> goto err;
> @@ -1965,7 +1944,6 @@ static int bttv_s_input(struct file *file, void *priv, unsigned int i)
> set_input(btv, i, btv->tvnorm);
>
> err:
> - mutex_unlock(&btv->lock);
> return 0;
> }
>
> @@ -1979,7 +1957,6 @@ static int bttv_s_tuner(struct file *file, void *priv,
> if (unlikely(0 != t->index))
> return -EINVAL;
>
> - mutex_lock(&btv->lock);
> if (unlikely(btv->tuner_type == TUNER_ABSENT)) {
> err = -EINVAL;
> goto err;
> @@ -1995,7 +1972,6 @@ static int bttv_s_tuner(struct file *file, void *priv,
> btv->audio_mode_gpio(btv, t, 1);
>
> err:
> - mutex_unlock(&btv->lock);
>
> return 0;
> }
> @@ -2006,10 +1982,8 @@ 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;
> }
> @@ -2024,7 +1998,6 @@ static int bttv_s_frequency(struct file *file, void *priv,
> if (unlikely(f->tuner != 0))
> return -EINVAL;
>
> - mutex_lock(&btv->lock);
> err = v4l2_prio_check(&btv->prio, fh->prio);
> if (unlikely(err))
> goto err;
> @@ -2039,7 +2012,6 @@ static int bttv_s_frequency(struct file *file, void *priv,
> if (btv->has_matchbox && btv->radio_user)
> tea5757_set_freq(btv, btv->freq);
> err:
> - mutex_unlock(&btv->lock);
>
> return 0;
> }
> @@ -2172,7 +2144,6 @@ limit_scaled_size_lock (struct bttv_fh * fh,
>
> /* Make sure tvnorm, vbi_end and the current cropping parameters
> remain consistent until we're done. */
> - mutex_lock(&btv->lock);
>
> b = &bttv_tvnorms[btv->tvnorm].cropcap.bounds;
>
> @@ -2250,7 +2221,6 @@ limit_scaled_size_lock (struct bttv_fh * fh,
> rc = 0; /* success */
>
> fail:
> - mutex_unlock(&btv->lock);
>
> return rc;
> }
> @@ -2282,9 +2252,7 @@ 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;
> @@ -2360,7 +2328,6 @@ static int setup_window_lock(struct bttv_fh *fh, struct bttv *btv,
> }
> }
>
> - 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,
> @@ -2412,7 +2379,6 @@ static int setup_window_lock(struct bttv_fh *fh, struct bttv *btv,
> bttv_overlay_risc(btv, &fh->ov, fh->ovfmt, new);
> retval = bttv_switch_overlay(btv,fh,new);
> }
> - mutex_unlock(&fh->cap.vb_lock);
> return retval;
> }
>
> @@ -2526,9 +2492,7 @@ 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;
> @@ -2614,7 +2578,6 @@ static int bttv_s_fmt_vid_cap(struct file *file, void *priv,
> fmt = format_by_fourcc(f->fmt.pix.pixelformat);
>
> /* update our state informations */
> - mutex_lock(&fh->cap.vb_lock);
> fh->fmt = fmt;
> fh->cap.field = f->fmt.pix.field;
> fh->cap.last = V4L2_FIELD_NONE;
> @@ -2623,7 +2586,6 @@ static int bttv_s_fmt_vid_cap(struct file *file, void *priv,
> btv->init.fmt = fmt;
> btv->init.width = f->fmt.pix.width;
> btv->init.height = f->fmt.pix.height;
> - mutex_unlock(&fh->cap.vb_lock);
>
> return 0;
> }
> @@ -2649,11 +2611,9 @@ static int vidiocgmbuf(struct file *file, void *priv, struct video_mbuf *mbuf)
> unsigned int i;
> struct bttv_fh *fh = priv;
>
> - mutex_lock(&fh->cap.vb_lock);
> retval = __videobuf_mmap_setup(&fh->cap, gbuffers, gbufsize,
> V4L2_MEMORY_MMAP);
> if (retval < 0) {
> - mutex_unlock(&fh->cap.vb_lock);
> return retval;
> }
>
> @@ -2665,7 +2625,6 @@ static int vidiocgmbuf(struct file *file, void *priv, struct video_mbuf *mbuf)
> for (i = 0; i < gbuffers; i++)
> mbuf->offsets[i] = i * gbufsize;
>
> - mutex_unlock(&fh->cap.vb_lock);
> return 0;
> }
> #endif
> @@ -2775,10 +2734,8 @@ static int bttv_overlay(struct file *file, void *f, unsigned int on)
> int retval = 0;
>
> if (on) {
> - mutex_lock(&fh->cap.vb_lock);
> /* verify args */
> if (unlikely(!btv->fbuf.base)) {
> - mutex_unlock(&fh->cap.vb_lock);
> return -EINVAL;
> }
> if (unlikely(!fh->ov.setup_ok)) {
> @@ -2787,13 +2744,11 @@ static int bttv_overlay(struct file *file, void *f, unsigned int on)
> }
> if (retval)
> return retval;
> - mutex_unlock(&fh->cap.vb_lock);
> }
>
> if (!check_alloc_btres_lock(btv, fh, RESOURCE_OVERLAY))
> return -EBUSY;
>
> - mutex_lock(&fh->cap.vb_lock);
> if (on) {
> fh->ov.tvnorm = btv->tvnorm;
> new = videobuf_sg_alloc(sizeof(*new));
> @@ -2805,7 +2760,6 @@ static int bttv_overlay(struct file *file, void *f, unsigned int on)
>
> /* switch over */
> retval = bttv_switch_overlay(btv, fh, new);
> - mutex_unlock(&fh->cap.vb_lock);
> return retval;
> }
>
> @@ -2844,7 +2798,6 @@ static int bttv_s_fbuf(struct file *file, void *f,
> }
>
> /* ok, accept it */
> - mutex_lock(&fh->cap.vb_lock);
> btv->fbuf.base = fb->base;
> btv->fbuf.fmt.width = fb->fmt.width;
> btv->fbuf.fmt.height = fb->fmt.height;
> @@ -2876,7 +2829,6 @@ static int bttv_s_fbuf(struct file *file, void *f,
> retval = bttv_switch_overlay(btv, fh, new);
> }
> }
> - mutex_unlock(&fh->cap.vb_lock);
> return retval;
> }
>
> @@ -2955,7 +2907,6 @@ 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 {
> @@ -2963,7 +2914,6 @@ static int bttv_queryctrl(struct file *file, void *priv,
>
> *c = (NULL != ctrl) ? *ctrl : no_ctl;
> }
> - mutex_unlock(&btv->lock);
>
> return 0;
> }
> @@ -2974,10 +2924,8 @@ 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;
> }
> @@ -2993,7 +2941,6 @@ static int bttv_g_tuner(struct file *file, void *priv,
> if (0 != t->index)
> return -EINVAL;
>
> - mutex_lock(&btv->lock);
> t->rxsubchans = V4L2_TUNER_SUB_MONO;
> bttv_call_all(btv, tuner, g_tuner, t);
> strcpy(t->name, "Television");
> @@ -3005,7 +2952,6 @@ static int bttv_g_tuner(struct file *file, void *priv,
> if (btv->audio_mode_gpio)
> btv->audio_mode_gpio(btv, t, 0);
>
> - mutex_unlock(&btv->lock);
> return 0;
> }
>
> @@ -3014,9 +2960,7 @@ 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;
> }
> @@ -3028,9 +2972,7 @@ static int bttv_s_priority(struct file *file, void *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 rc;
> }
> @@ -3045,9 +2987,7 @@ 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;
> }
> @@ -3065,9 +3005,7 @@ 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;
> }
> @@ -3091,17 +3029,14 @@ static int bttv_s_crop(struct file *file, void *f, struct v4l2_crop *crop)
> /* 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;
>
> if (locked_btres(fh->btv, VIDEO_RESOURCES)) {
> - mutex_unlock(&btv->lock);
> return retval;
> }
>
> @@ -3113,7 +3048,6 @@ static int bttv_s_crop(struct file *file, void *f, struct v4l2_crop *crop)
>
> b_top = max(b->top, btv->vbi_end);
> if (b_top + 32 >= b_bottom) {
> - mutex_unlock(&btv->lock);
> return retval;
> }
>
> @@ -3136,12 +3070,8 @@ static int bttv_s_crop(struct file *file, void *f, struct v4l2_crop *crop)
>
> btv->crop[1] = c;
>
> - mutex_unlock(&btv->lock);
> -
> fh->do_crop = 1;
>
> - mutex_lock(&fh->cap.vb_lock);
> -
> if (fh->width < c.min_scaled_width) {
> fh->width = c.min_scaled_width;
> btv->init.width = c.min_scaled_width;
> @@ -3158,8 +3088,6 @@ static int bttv_s_crop(struct file *file, void *f, struct v4l2_crop *crop)
> btv->init.height = c.max_scaled_height;
> }
>
> - mutex_unlock(&fh->cap.vb_lock);
> -
> return 0;
> }
>
> @@ -3227,7 +3155,6 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait)
> return videobuf_poll_stream(file, &fh->vbi, wait);
> }
>
> - mutex_lock(&fh->cap.vb_lock);
> if (check_btres(fh,RESOURCE_VIDEO_STREAM)) {
> /* streaming capture */
> if (list_empty(&fh->cap.stream))
> @@ -3262,7 +3189,6 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait)
> else
> rc = 0;
> err:
> - mutex_unlock(&fh->cap.vb_lock);
> return rc;
> }
>
> @@ -3302,14 +3228,11 @@ static int bttv_open(struct file *file)
> * 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,
> @@ -3317,13 +3240,13 @@ static int bttv_open(struct file *file)
> V4L2_BUF_TYPE_VIDEO_CAPTURE,
> V4L2_FIELD_INTERLACED,
> sizeof(struct bttv_buffer),
> - fh, NULL);
> + fh, &btv->lock);
> videobuf_queue_sg_init(&fh->vbi, &bttv_vbi_qops,
> &btv->c.pci->dev, &btv->s_lock,
> V4L2_BUF_TYPE_VBI_CAPTURE,
> V4L2_FIELD_SEQ_TB,
> sizeof(struct bttv_buffer),
> - fh, NULL);
> + fh, &btv->lock);
> set_tvnorm(btv,btv->tvnorm);
> set_input(btv, btv->input, btv->tvnorm);
>
> @@ -3346,7 +3269,6 @@ static int bttv_open(struct file *file)
> bttv_vbi_fmt_reset(&fh->vbi_fmt, btv->tvnorm);
>
> bttv_field_count(btv);
> - mutex_unlock(&btv->lock);
> return 0;
> }
>
> @@ -3355,7 +3277,6 @@ 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);
> @@ -3385,10 +3306,8 @@ static int bttv_release(struct file *file)
> * 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);
> @@ -3398,7 +3317,6 @@ static int bttv_release(struct file *file)
>
> if (!btv->users)
> audio_mute(btv, 1);
> - mutex_unlock(&btv->lock);
>
> return 0;
> }
> @@ -3502,11 +3420,8 @@ static int radio_open(struct file *file)
> if (unlikely(!fh))
> return -ENOMEM;
> file->private_data = fh;
> - mutex_lock(&fh->cap.vb_lock);
> *fh = btv->init;
> - mutex_unlock(&fh->cap.vb_lock);
>
> - mutex_lock(&btv->lock);
> v4l2_prio_open(&btv->prio, &fh->prio);
>
> btv->radio_user++;
> @@ -3514,7 +3429,6 @@ static int radio_open(struct file *file)
> bttv_call_all(btv, tuner, s_radio);
> audio_input(btv,TVAUDIO_INPUT_RADIO);
>
> - mutex_unlock(&btv->lock);
> return 0;
> }
>
> @@ -3524,7 +3438,6 @@ 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);
> @@ -3532,7 +3445,6 @@ 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;
> }
> @@ -3561,7 +3473,6 @@ static int radio_g_tuner(struct file *file, void *priv, struct v4l2_tuner *t)
> return -EINVAL;
> if (0 != t->index)
> return -EINVAL;
> - mutex_lock(&btv->lock);
> strcpy(t->name, "Radio");
> t->type = V4L2_TUNER_RADIO;
>
> @@ -3570,8 +3481,6 @@ static int radio_g_tuner(struct file *file, void *priv, struct v4l2_tuner *t)
> if (btv->audio_mode_gpio)
> btv->audio_mode_gpio(btv, t, 0);
>
> - mutex_unlock(&btv->lock);
> -
> return 0;
> }
>
> @@ -3692,7 +3601,7 @@ static const struct v4l2_file_operations radio_fops =
> .open = radio_open,
> .read = radio_read,
> .release = radio_release,
> - .ioctl = video_ioctl2,
> + .unlocked_ioctl = video_ioctl2,
> .poll = radio_poll,
> };
>
>
