diff options
author | Hans Verkuil <hans.verkuil@cisco.com> | 2012-05-06 14:28:27 +0200 |
---|---|---|
committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2012-05-14 14:31:03 +0200 |
commit | a3d6e8cc0e6ddc8b3cfdeb3c979f07ed1aa528b3 (patch) | |
tree | 60e69fcac849b505328e5755ee71195d0bc6728b | |
parent | [media] gspca: Fix locking issues related to suspend/resume (diff) | |
download | linux-a3d6e8cc0e6ddc8b3cfdeb3c979f07ed1aa528b3.tar.xz linux-a3d6e8cc0e6ddc8b3cfdeb3c979f07ed1aa528b3.zip |
[media] gspca: Switch to V4L2 core locking, except for the buffer queuing ioctls
Due to latency concerns the VIDIOC_QBUF, DQBUF and QUERYBUF do not use the
core lock, instead they rely only on queue_lock.
Changes by HdG:
1) Change release from the video_device to the v4l2_device, to avoid a
race on disconnect.
2) Adjust for the V4L2 core changes which cause non ioctl fops to no longer
take the V4L2 core lock.
[mchehab@redhat.com: fix a merge conflict]
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
-rw-r--r-- | drivers/media/video/gspca/gspca.c | 257 | ||||
-rw-r--r-- | drivers/media/video/gspca/gspca.h | 7 |
2 files changed, 82 insertions, 182 deletions
diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c index a14c8f71d48b..2687e76b0fb8 100644 --- a/drivers/media/video/gspca/gspca.c +++ b/drivers/media/video/gspca/gspca.c @@ -850,14 +850,6 @@ static int gspca_init_transfer(struct gspca_dev *gspca_dev) struct ep_tb_s ep_tb[MAX_ALT]; int n, ret, xfer, alt, alt_idx; - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; - - if (!gspca_dev->present) { - ret = -ENODEV; - goto unlock; - } - /* reset the streaming variables */ gspca_dev->image = NULL; gspca_dev->image_len = 0; @@ -872,7 +864,7 @@ static int gspca_init_transfer(struct gspca_dev *gspca_dev) if (gspca_dev->sd_desc->isoc_init) { ret = gspca_dev->sd_desc->isoc_init(gspca_dev); if (ret < 0) - goto unlock; + return ret; } xfer = gspca_dev->cam.bulk ? USB_ENDPOINT_XFER_BULK : USB_ENDPOINT_XFER_ISOC; @@ -883,8 +875,7 @@ static int gspca_init_transfer(struct gspca_dev *gspca_dev) ep = alt_xfer(&intf->altsetting[gspca_dev->alt], xfer); if (ep == NULL) { pr_err("bad altsetting %d\n", gspca_dev->alt); - ret = -EIO; - goto out; + return -EIO; } ep_tb[0].alt = gspca_dev->alt; alt_idx = 1; @@ -895,8 +886,7 @@ static int gspca_init_transfer(struct gspca_dev *gspca_dev) alt_idx = build_isoc_ep_tb(gspca_dev, intf, ep_tb); if (alt_idx <= 0) { pr_err("no transfer endpoint found\n"); - ret = -EIO; - goto unlock; + return -EIO; } } @@ -991,8 +981,6 @@ retry: } out: gspca_input_create_urb(gspca_dev); -unlock: - mutex_unlock(&gspca_dev->usb_lock); return ret; } @@ -1062,7 +1050,6 @@ static int gspca_get_mode(struct gspca_dev *gspca_dev, static int vidioc_g_register(struct file *file, void *priv, struct v4l2_dbg_register *reg) { - int ret; struct gspca_dev *gspca_dev = video_drvdata(file); if (!gspca_dev->sd_desc->get_chip_ident) @@ -1071,22 +1058,13 @@ static int vidioc_g_register(struct file *file, void *priv, if (!gspca_dev->sd_desc->get_register) return -ENOTTY; - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; gspca_dev->usb_err = 0; - if (gspca_dev->present) - ret = gspca_dev->sd_desc->get_register(gspca_dev, reg); - else - ret = -ENODEV; - mutex_unlock(&gspca_dev->usb_lock); - - return ret; + return gspca_dev->sd_desc->get_register(gspca_dev, reg); } static int vidioc_s_register(struct file *file, void *priv, struct v4l2_dbg_register *reg) { - int ret; struct gspca_dev *gspca_dev = video_drvdata(file); if (!gspca_dev->sd_desc->get_chip_ident) @@ -1095,38 +1073,21 @@ static int vidioc_s_register(struct file *file, void *priv, if (!gspca_dev->sd_desc->set_register) return -ENOTTY; - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; gspca_dev->usb_err = 0; - if (gspca_dev->present) - ret = gspca_dev->sd_desc->set_register(gspca_dev, reg); - else - ret = -ENODEV; - mutex_unlock(&gspca_dev->usb_lock); - - return ret; + return gspca_dev->sd_desc->set_register(gspca_dev, reg); } #endif static int vidioc_g_chip_ident(struct file *file, void *priv, struct v4l2_dbg_chip_ident *chip) { - int ret; struct gspca_dev *gspca_dev = video_drvdata(file); if (!gspca_dev->sd_desc->get_chip_ident) return -ENOTTY; - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; gspca_dev->usb_err = 0; - if (gspca_dev->present) - ret = gspca_dev->sd_desc->get_chip_ident(gspca_dev, chip); - else - ret = -ENODEV; - mutex_unlock(&gspca_dev->usb_lock); - - return ret; + return gspca_dev->sd_desc->get_chip_ident(gspca_dev, chip); } static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv, @@ -1321,9 +1282,10 @@ static int vidioc_enum_frameintervals(struct file *filp, void *priv, return -EINVAL; } -static void gspca_release(struct video_device *vfd) +static void gspca_release(struct v4l2_device *v4l2_device) { - struct gspca_dev *gspca_dev = container_of(vfd, struct gspca_dev, vdev); + struct gspca_dev *gspca_dev = + container_of(v4l2_device, struct gspca_dev, v4l2_dev); PDEBUG(D_PROBE, "%s released", video_device_node_name(&gspca_dev->vdev)); @@ -1339,8 +1301,6 @@ static int dev_open(struct file *file) struct gspca_dev *gspca_dev = video_drvdata(file); PDEBUG(D_STREAM, "[%s] open", current->comm); - if (!gspca_dev->present) - return -ENODEV; /* protect the subdriver against rmmod */ if (!try_module_get(gspca_dev->module)) @@ -1363,21 +1323,27 @@ static int dev_close(struct file *file) struct gspca_dev *gspca_dev = video_drvdata(file); PDEBUG(D_STREAM, "[%s] close", current->comm); - if (mutex_lock_interruptible(&gspca_dev->queue_lock)) + + /* Needed for gspca_stream_off, always lock before queue_lock! */ + if (mutex_lock_interruptible(&gspca_dev->usb_lock)) return -ERESTARTSYS; + if (mutex_lock_interruptible(&gspca_dev->queue_lock)) { + mutex_unlock(&gspca_dev->usb_lock); + return -ERESTARTSYS; + } + /* if the file did the capture, free the streaming resources */ if (gspca_dev->capt_file == file) { if (gspca_dev->streaming) { - mutex_lock(&gspca_dev->usb_lock); gspca_dev->usb_err = 0; gspca_stream_off(gspca_dev); - mutex_unlock(&gspca_dev->usb_lock); } frame_free(gspca_dev); } module_put(gspca_dev->module); mutex_unlock(&gspca_dev->queue_lock); + mutex_unlock(&gspca_dev->usb_lock); PDEBUG(D_STREAM, "close done"); @@ -1388,15 +1354,7 @@ static int vidioc_querycap(struct file *file, void *priv, struct v4l2_capability *cap) { struct gspca_dev *gspca_dev = video_drvdata(file); - int ret; - /* protect the access to the usb device */ - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; - if (!gspca_dev->present) { - ret = -ENODEV; - goto out; - } strlcpy((char *) cap->driver, gspca_dev->sd_desc->name, sizeof cap->driver); if (gspca_dev->dev->product != NULL) { @@ -1414,10 +1372,7 @@ static int vidioc_querycap(struct file *file, void *priv, | V4L2_CAP_STREAMING | V4L2_CAP_READWRITE; cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS; - ret = 0; -out: - mutex_unlock(&gspca_dev->usb_lock); - return ret; + return 0; } static int get_ctrl(struct gspca_dev *gspca_dev, @@ -1486,7 +1441,7 @@ static int vidioc_s_ctrl(struct file *file, void *priv, struct gspca_dev *gspca_dev = video_drvdata(file); const struct ctrl *ctrls; struct gspca_ctrl *gspca_ctrl; - int idx, ret; + int idx; idx = get_ctrl(gspca_dev, ctrl->id); if (idx < 0) @@ -1506,27 +1461,16 @@ static int vidioc_s_ctrl(struct file *file, void *priv, return -ERANGE; } PDEBUG(D_CONF, "set ctrl [%08x] = %d", ctrl->id, ctrl->value); - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; - if (!gspca_dev->present) { - ret = -ENODEV; - goto out; - } gspca_dev->usb_err = 0; - if (ctrls->set != NULL) { - ret = ctrls->set(gspca_dev, ctrl->value); - goto out; - } + if (ctrls->set != NULL) + return ctrls->set(gspca_dev, ctrl->value); if (gspca_ctrl != NULL) { gspca_ctrl->val = ctrl->value; if (ctrls->set_control != NULL && gspca_dev->streaming) ctrls->set_control(gspca_dev); } - ret = gspca_dev->usb_err; -out: - mutex_unlock(&gspca_dev->usb_lock); - return ret; + return gspca_dev->usb_err; } static int vidioc_g_ctrl(struct file *file, void *priv, @@ -1534,30 +1478,19 @@ static int vidioc_g_ctrl(struct file *file, void *priv, { struct gspca_dev *gspca_dev = video_drvdata(file); const struct ctrl *ctrls; - int idx, ret; + int idx; idx = get_ctrl(gspca_dev, ctrl->id); if (idx < 0) return -EINVAL; ctrls = &gspca_dev->sd_desc->ctrls[idx]; - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; - if (!gspca_dev->present) { - ret = -ENODEV; - goto out; - } gspca_dev->usb_err = 0; - if (ctrls->get != NULL) { - ret = ctrls->get(gspca_dev, &ctrl->value); - goto out; - } + if (ctrls->get != NULL) + return ctrls->get(gspca_dev, &ctrl->value); if (gspca_dev->cam.ctrls != NULL) ctrl->value = gspca_dev->cam.ctrls[idx].val; - ret = 0; -out: - mutex_unlock(&gspca_dev->usb_lock); - return ret; + return 0; } static int vidioc_querymenu(struct file *file, void *priv, @@ -1640,10 +1573,8 @@ static int vidioc_reqbufs(struct file *file, void *priv, /* stop streaming */ streaming = gspca_dev->streaming; if (streaming) { - mutex_lock(&gspca_dev->usb_lock); gspca_dev->usb_err = 0; gspca_stream_off(gspca_dev); - mutex_unlock(&gspca_dev->usb_lock); /* Don't restart the stream when switching from read * to mmap mode */ @@ -1748,13 +1679,8 @@ static int vidioc_streamoff(struct file *file, void *priv, } /* stop streaming */ - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) { - ret = -ERESTARTSYS; - goto out; - } gspca_dev->usb_err = 0; gspca_stream_off(gspca_dev); - mutex_unlock(&gspca_dev->usb_lock); /* In case another thread is waiting in dqbuf */ wake_up_interruptible(&gspca_dev->wq); @@ -1772,38 +1698,22 @@ static int vidioc_g_jpegcomp(struct file *file, void *priv, struct v4l2_jpegcompression *jpegcomp) { struct gspca_dev *gspca_dev = video_drvdata(file); - int ret; if (!gspca_dev->sd_desc->get_jcomp) return -ENOTTY; - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; gspca_dev->usb_err = 0; - if (gspca_dev->present) - ret = gspca_dev->sd_desc->get_jcomp(gspca_dev, jpegcomp); - else - ret = -ENODEV; - mutex_unlock(&gspca_dev->usb_lock); - return ret; + return gspca_dev->sd_desc->get_jcomp(gspca_dev, jpegcomp); } static int vidioc_s_jpegcomp(struct file *file, void *priv, struct v4l2_jpegcompression *jpegcomp) { struct gspca_dev *gspca_dev = video_drvdata(file); - int ret; if (!gspca_dev->sd_desc->set_jcomp) return -ENOTTY; - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; gspca_dev->usb_err = 0; - if (gspca_dev->present) - ret = gspca_dev->sd_desc->set_jcomp(gspca_dev, jpegcomp); - else - ret = -ENODEV; - mutex_unlock(&gspca_dev->usb_lock); - return ret; + return gspca_dev->sd_desc->set_jcomp(gspca_dev, jpegcomp); } static int vidioc_g_parm(struct file *filp, void *priv, @@ -1814,21 +1724,10 @@ static int vidioc_g_parm(struct file *filp, void *priv, parm->parm.capture.readbuffers = gspca_dev->nbufread; if (gspca_dev->sd_desc->get_streamparm) { - int ret; - - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; - if (gspca_dev->present) { - gspca_dev->usb_err = 0; - gspca_dev->sd_desc->get_streamparm(gspca_dev, parm); - ret = gspca_dev->usb_err; - } else { - ret = -ENODEV; - } - mutex_unlock(&gspca_dev->usb_lock); - return ret; + gspca_dev->usb_err = 0; + gspca_dev->sd_desc->get_streamparm(gspca_dev, parm); + return gspca_dev->usb_err; } - return 0; } @@ -1845,19 +1744,9 @@ static int vidioc_s_parm(struct file *filp, void *priv, gspca_dev->nbufread = n; if (gspca_dev->sd_desc->set_streamparm) { - int ret; - - if (mutex_lock_interruptible(&gspca_dev->usb_lock)) - return -ERESTARTSYS; - if (gspca_dev->present) { - gspca_dev->usb_err = 0; - gspca_dev->sd_desc->set_streamparm(gspca_dev, parm); - ret = gspca_dev->usb_err; - } else { - ret = -ENODEV; - } - mutex_unlock(&gspca_dev->usb_lock); - return ret; + gspca_dev->usb_err = 0; + gspca_dev->sd_desc->set_streamparm(gspca_dev, parm); + return gspca_dev->usb_err; } return 0; @@ -1877,10 +1766,6 @@ static int dev_mmap(struct file *file, struct vm_area_struct *vma) if (mutex_lock_interruptible(&gspca_dev->queue_lock)) return -ERESTARTSYS; - if (!gspca_dev->present) { - ret = -ENODEV; - goto out; - } if (gspca_dev->capt_file != file) { ret = -EINVAL; goto out; @@ -2008,14 +1893,6 @@ static int vidioc_dqbuf(struct file *file, void *priv, gspca_dev->fr_o = (i + 1) % GSPCA_MAX_FRAMES; - if (gspca_dev->sd_desc->dq_callback) { - mutex_lock(&gspca_dev->usb_lock); - gspca_dev->usb_err = 0; - if (gspca_dev->present) - gspca_dev->sd_desc->dq_callback(gspca_dev); - mutex_unlock(&gspca_dev->usb_lock); - } - frame->v4l2_buf.flags &= ~V4L2_BUF_FLAG_DONE; memcpy(v4l2_buf, &frame->v4l2_buf, sizeof *v4l2_buf); PDEBUG(D_FRAM, "dqbuf %d", j); @@ -2032,6 +1909,15 @@ static int vidioc_dqbuf(struct file *file, void *priv, } out: mutex_unlock(&gspca_dev->queue_lock); + + if (ret == 0 && gspca_dev->sd_desc->dq_callback) { + mutex_lock(&gspca_dev->usb_lock); + gspca_dev->usb_err = 0; + if (gspca_dev->present) + gspca_dev->sd_desc->dq_callback(gspca_dev); + mutex_unlock(&gspca_dev->usb_lock); + } + return ret; } @@ -2103,6 +1989,10 @@ static int read_alloc(struct gspca_dev *gspca_dev, int i, ret; PDEBUG(D_STREAM, "read alloc"); + + if (mutex_lock_interruptible(&gspca_dev->usb_lock)) + return -ERESTARTSYS; + if (gspca_dev->nframes == 0) { struct v4l2_requestbuffers rb; @@ -2113,7 +2003,7 @@ static int read_alloc(struct gspca_dev *gspca_dev, ret = vidioc_reqbufs(file, gspca_dev, &rb); if (ret != 0) { PDEBUG(D_STREAM, "read reqbuf err %d", ret); - return ret; + goto out; } memset(&v4l2_buf, 0, sizeof v4l2_buf); v4l2_buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; @@ -2123,16 +2013,17 @@ static int read_alloc(struct gspca_dev *gspca_dev, ret = vidioc_qbuf(file, gspca_dev, &v4l2_buf); if (ret != 0) { PDEBUG(D_STREAM, "read qbuf err: %d", ret); - return ret; + goto out; } } - gspca_dev->memory = GSPCA_MEMORY_READ; } /* start streaming */ ret = vidioc_streamon(file, gspca_dev, V4L2_BUF_TYPE_VIDEO_CAPTURE); if (ret != 0) PDEBUG(D_STREAM, "read streamon err %d", ret); +out: + mutex_unlock(&gspca_dev->usb_lock); return ret; } @@ -2177,8 +2068,6 @@ static ssize_t dev_read(struct file *file, char __user *data, int n, ret, ret2; PDEBUG(D_FRAM, "read (%zd)", count); - if (!gspca_dev->present) - return -ENODEV; if (gspca_dev->memory == GSPCA_MEMORY_NO) { /* first time ? */ ret = read_alloc(gspca_dev, file); if (ret != 0) @@ -2280,7 +2169,7 @@ static const struct video_device gspca_template = { .name = "gspca main driver", .fops = &dev_fops, .ioctl_ops = &dev_ioctl_ops, - .release = gspca_release, + .release = video_device_release_empty, /* We use v4l2_dev.release */ }; /* initialize the controls */ @@ -2352,6 +2241,7 @@ int gspca_dev_probe2(struct usb_interface *intf, } } + gspca_dev->v4l2_dev.release = gspca_release; ret = v4l2_device_register(&intf->dev, &gspca_dev->v4l2_dev); if (ret) goto out; @@ -2366,6 +2256,7 @@ int gspca_dev_probe2(struct usb_interface *intf, gspca_dev->present = 1; mutex_init(&gspca_dev->usb_lock); + gspca_dev->vdev.lock = &gspca_dev->usb_lock; mutex_init(&gspca_dev->queue_lock); init_waitqueue_head(&gspca_dev->wq); @@ -2388,6 +2279,15 @@ int gspca_dev_probe2(struct usb_interface *intf, if (ret) goto out; + /* + * Don't take usb_lock for these ioctls. This improves latency if + * usb_lock is taken for a long time, e.g. when changing a control + * value, and a new frame is ready to be dequeued. + */ + v4l2_dont_use_lock(&gspca_dev->vdev, VIDIOC_DQBUF); + v4l2_dont_use_lock(&gspca_dev->vdev, VIDIOC_QBUF); + v4l2_dont_use_lock(&gspca_dev->vdev, VIDIOC_QUERYBUF); + /* init video stuff */ ret = video_register_device(&gspca_dev->vdev, VFL_TYPE_GRABBER, @@ -2455,11 +2355,13 @@ void gspca_disconnect(struct usb_interface *intf) PDEBUG(D_PROBE, "%s disconnect", video_device_node_name(&gspca_dev->vdev)); + mutex_lock(&gspca_dev->usb_lock); + usb_set_intfdata(intf, NULL); + gspca_dev->dev = NULL; gspca_dev->present = 0; wake_up_interruptible(&gspca_dev->wq); - destroy_urbs(gspca_dev); #if defined(CONFIG_INPUT) || defined(CONFIG_INPUT_MODULE) @@ -2471,18 +2373,13 @@ void gspca_disconnect(struct usb_interface *intf) } #endif - /* the device is freed at exit of this function */ - gspca_dev->dev = NULL; v4l2_device_disconnect(&gspca_dev->v4l2_dev); - mutex_unlock(&gspca_dev->usb_lock); + video_unregister_device(&gspca_dev->vdev); - usb_set_intfdata(intf, NULL); + mutex_unlock(&gspca_dev->usb_lock); - /* release the device */ /* (this will call gspca_release() immediately or on last close) */ - video_unregister_device(&gspca_dev->vdev); - -/* PDEBUG(D_PROBE, "disconnect complete"); */ + v4l2_device_put(&gspca_dev->v4l2_dev); } EXPORT_SYMBOL(gspca_disconnect); @@ -2493,17 +2390,16 @@ int gspca_suspend(struct usb_interface *intf, pm_message_t message) if (!gspca_dev->streaming) return 0; + mutex_lock(&gspca_dev->usb_lock); gspca_dev->frozen = 1; /* avoid urb error messages */ if (gspca_dev->sd_desc->stopN) gspca_dev->sd_desc->stopN(gspca_dev); destroy_urbs(gspca_dev); gspca_input_destroy_urb(gspca_dev); gspca_set_alt0(gspca_dev); - if (gspca_dev->sd_desc->stop0) { - mutex_lock(&gspca_dev->usb_lock); + if (gspca_dev->sd_desc->stop0) gspca_dev->sd_desc->stop0(gspca_dev); - mutex_unlock(&gspca_dev->usb_lock); - } + mutex_unlock(&gspca_dev->usb_lock); return 0; } EXPORT_SYMBOL(gspca_suspend); @@ -2513,6 +2409,7 @@ int gspca_resume(struct usb_interface *intf) struct gspca_dev *gspca_dev = usb_get_intfdata(intf); int streaming, ret = 0; + mutex_lock(&gspca_dev->usb_lock); gspca_dev->frozen = 0; gspca_dev->sd_desc->init(gspca_dev); gspca_input_create_urb(gspca_dev); @@ -2524,11 +2421,9 @@ int gspca_resume(struct usb_interface *intf) streaming = gspca_dev->streaming; gspca_dev->streaming = 0; v4l2_ctrl_handler_setup(gspca_dev->vdev.ctrl_handler); - if (streaming) { - mutex_lock(&gspca_dev->queue_lock); + if (streaming) ret = gspca_init_transfer(gspca_dev); - mutex_unlock(&gspca_dev->queue_lock); - } + mutex_unlock(&gspca_dev->usb_lock); return ret; } EXPORT_SYMBOL(gspca_resume); diff --git a/drivers/media/video/gspca/gspca.h b/drivers/media/video/gspca/gspca.h index c1ebf7cd45b3..436d881ce443 100644 --- a/drivers/media/video/gspca/gspca.h +++ b/drivers/media/video/gspca/gspca.h @@ -163,6 +163,7 @@ struct gspca_dev { struct v4l2_device v4l2_dev; struct usb_device *dev; struct file *capt_file; /* file doing video capture */ + /* protected by queue_lock */ #if defined(CONFIG_INPUT) || defined(CONFIG_INPUT_MODULE) struct input_dev *input_dev; char phys[64]; /* physical device path */ @@ -192,7 +193,7 @@ struct gspca_dev { u8 fr_o; /* next frame to dequeue */ __u8 last_packet_type; __s8 empty_packet; /* if (-1) don't check empty packets */ - __u8 streaming; + __u8 streaming; /* protected by both mutexes (*) */ __u8 curr_mode; /* current camera mode */ __u32 pixfmt; /* current mode parameters */ @@ -214,6 +215,10 @@ struct gspca_dev { __u8 iface; /* USB interface number */ __u8 alt; /* USB alternate setting */ u8 audio; /* presence of audio device */ + + /* (*) These variables are proteced by both usb_lock and queue_lock, + that is any code setting them is holding *both*, which means that + any code getting them needs to hold at least one of them */ }; int gspca_dev_probe(struct usb_interface *intf, |