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[35.245.224.76]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-45b5264b629sm22406781cf.64.2024.09.25.22.50.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Sep 2024 22:50:09 -0700 (PDT) From: Ricardo Ribalda Date: Thu, 26 Sep 2024 05:49:57 +0000 Subject: [PATCH v7 1/3] media: uvcvideo: Refactor the status irq API Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240926-guenter-mini-v7-1-690441953d4a@chromium.org> References: <20240926-guenter-mini-v7-0-690441953d4a@chromium.org> In-Reply-To: <20240926-guenter-mini-v7-0-690441953d4a@chromium.org> To: Mauro Carvalho Chehab Cc: Guenter Roeck , Tomasz Figa , Laurent Pinchart , Alan Stern , Hans Verkuil , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Paul , Ricardo Ribalda , Sakari Ailus , Sergey Senozhatsky X-Mailer: b4 0.13.0 There are two different use-cases of uvc_status(): - adding/removing a user when the camera is open/closed - stopping/starting when the camera is suspended/resumed Make the API reflect these two use-cases and move all the refcounting and locking logic to the uvc_status.c file. No functional change is expected from this patch. Reviewed-by: Sergey Senozhatsky Signed-off-by: Ricardo Ribalda --- drivers/media/usb/uvc/uvc_driver.c | 13 ++-------- drivers/media/usb/uvc/uvc_status.c | 53 ++++++++++++++++++++++++++++++++++++-- drivers/media/usb/uvc/uvc_v4l2.c | 22 +++++----------- drivers/media/usb/uvc/uvcvideo.h | 10 ++++--- 4 files changed, 65 insertions(+), 33 deletions(-) diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index f0febdc08c2d..31e8942f1ef8 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -2116,7 +2116,6 @@ static int uvc_probe(struct usb_interface *intf, INIT_LIST_HEAD(&dev->streams); kref_init(&dev->ref); atomic_set(&dev->nmappings, 0); - mutex_init(&dev->lock); dev->udev = usb_get_dev(udev); dev->intf = usb_get_intf(intf); @@ -2288,10 +2287,7 @@ static int uvc_suspend(struct usb_interface *intf, pm_message_t message) /* Controls are cached on the fly so they don't need to be saved. */ if (intf->cur_altsetting->desc.bInterfaceSubClass == UVC_SC_VIDEOCONTROL) { - mutex_lock(&dev->lock); - if (dev->users) - uvc_status_stop(dev); - mutex_unlock(&dev->lock); + uvc_status_suspend(dev); return 0; } @@ -2322,12 +2318,7 @@ static int __uvc_resume(struct usb_interface *intf, int reset) return ret; } - mutex_lock(&dev->lock); - if (dev->users) - ret = uvc_status_start(dev, GFP_NOIO); - mutex_unlock(&dev->lock); - - return ret; + return uvc_status_resume(dev); } list_for_each_entry(stream, &dev->streams, list) { diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c index a78a88c710e2..e438ae5af2e8 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -257,6 +257,8 @@ int uvc_status_init(struct uvc_device *dev) unsigned int pipe; int interval; + mutex_init(&dev->status_lock); + if (ep == NULL) return 0; @@ -302,18 +304,22 @@ void uvc_status_cleanup(struct uvc_device *dev) kfree(dev->status); } -int uvc_status_start(struct uvc_device *dev, gfp_t flags) +static int uvc_status_start(struct uvc_device *dev, gfp_t flags) { + lockdep_assert_held(&dev->status_lock); + if (dev->int_urb == NULL) return 0; return usb_submit_urb(dev->int_urb, flags); } -void uvc_status_stop(struct uvc_device *dev) +static void uvc_status_stop(struct uvc_device *dev) { struct uvc_ctrl_work *w = &dev->async_ctrl; + lockdep_assert_held(&dev->status_lock); + /* * Prevent the asynchronous control handler from requeing the URB. The * barrier is needed so the flush_status change is visible to other @@ -350,3 +356,46 @@ void uvc_status_stop(struct uvc_device *dev) */ smp_store_release(&dev->flush_status, false); } + +int uvc_status_resume(struct uvc_device *dev) +{ + guard(mutex)(&dev->status_lock); + + if (dev->status_users) + return uvc_status_start(dev, GFP_NOIO); + + return 0; +} + +void uvc_status_suspend(struct uvc_device *dev) +{ + guard(mutex)(&dev->status_lock); + + if (dev->status_users) + uvc_status_stop(dev); +} + +int uvc_status_get(struct uvc_device *dev) +{ + int ret = 0; + + guard(mutex)(&dev->status_lock); + + if (!dev->status_users) + ret = uvc_status_start(dev, GFP_KERNEL); + if (!ret) + dev->status_users++; + + return ret; +} + +void uvc_status_put(struct uvc_device *dev) +{ + guard(mutex)(&dev->status_lock); + + if (dev->status_users == 1) + uvc_status_stop(dev); + WARN_ON(!dev->status_users); + if (dev->status_users) + dev->status_users--; +} diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c index f4988f03640a..97c5407f6603 100644 --- a/drivers/media/usb/uvc/uvc_v4l2.c +++ b/drivers/media/usb/uvc/uvc_v4l2.c @@ -628,20 +628,13 @@ static int uvc_v4l2_open(struct file *file) return -ENOMEM; } - mutex_lock(&stream->dev->lock); - if (stream->dev->users == 0) { - ret = uvc_status_start(stream->dev, GFP_KERNEL); - if (ret < 0) { - mutex_unlock(&stream->dev->lock); - usb_autopm_put_interface(stream->dev->intf); - kfree(handle); - return ret; - } + ret = uvc_status_get(stream->dev); + if (ret) { + usb_autopm_put_interface(stream->dev->intf); + kfree(handle); + return ret; } - stream->dev->users++; - mutex_unlock(&stream->dev->lock); - v4l2_fh_init(&handle->vfh, &stream->vdev); v4l2_fh_add(&handle->vfh); handle->chain = stream->chain; @@ -670,10 +663,7 @@ static int uvc_v4l2_release(struct file *file) kfree(handle); file->private_data = NULL; - mutex_lock(&stream->dev->lock); - if (--stream->dev->users == 0) - uvc_status_stop(stream->dev); - mutex_unlock(&stream->dev->lock); + uvc_status_put(stream->dev); usb_autopm_put_interface(stream->dev->intf); return 0; diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index b7d24a853ce4..07f9921d83f2 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -563,8 +563,6 @@ struct uvc_device { const struct uvc_device_info *info; - struct mutex lock; /* Protects users */ - unsigned int users; atomic_t nmappings; /* Video control interface */ @@ -586,6 +584,8 @@ struct uvc_device { struct usb_host_endpoint *int_ep; struct urb *int_urb; struct uvc_status *status; + struct mutex status_lock; /* Protects status_users */ + unsigned int status_users; bool flush_status; struct input_dev *input; @@ -752,8 +752,10 @@ int uvc_register_video_device(struct uvc_device *dev, int uvc_status_init(struct uvc_device *dev); void uvc_status_unregister(struct uvc_device *dev); void uvc_status_cleanup(struct uvc_device *dev); -int uvc_status_start(struct uvc_device *dev, gfp_t flags); -void uvc_status_stop(struct uvc_device *dev); +int uvc_status_resume(struct uvc_device *dev); +void uvc_status_suspend(struct uvc_device *dev); +int uvc_status_get(struct uvc_device *dev); +void uvc_status_put(struct uvc_device *dev); /* Controls */ extern const struct v4l2_subscribed_event_ops uvc_ctrl_sub_ev_ops; From patchwork Thu Sep 26 05:49:58 2024 Content-Type: text/plain; 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[35.245.224.76]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-45b5264b629sm22406781cf.64.2024.09.25.22.50.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Sep 2024 22:50:10 -0700 (PDT) From: Ricardo Ribalda Date: Thu, 26 Sep 2024 05:49:58 +0000 Subject: [PATCH v7 2/3] media: uvcvideo: Avoid race condition during unregister Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240926-guenter-mini-v7-2-690441953d4a@chromium.org> References: <20240926-guenter-mini-v7-0-690441953d4a@chromium.org> In-Reply-To: <20240926-guenter-mini-v7-0-690441953d4a@chromium.org> To: Mauro Carvalho Chehab Cc: Guenter Roeck , Tomasz Figa , Laurent Pinchart , Alan Stern , Hans Verkuil , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Paul , Ricardo Ribalda , Sakari Ailus , Sergey Senozhatsky X-Mailer: b4 0.13.0 The control events are handled asynchronously by the driver. Once the control event are handled, the urb is re-submitted. If we simply kill the urb, there is a chance that a control event is waiting to be processed, which will re-submit the urb after the device is disconnected. Fix this by calling uvc_status_suspend(), which flushes the async controls and kills the URB in a race-free manner. Reviewed-by: Laurent Pinchart Reviewed-by: Sergey Senozhatsky Signed-off-by: Ricardo Ribalda --- drivers/media/usb/uvc/uvc_status.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c index e438ae5af2e8..d8d5b327693f 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -294,7 +294,7 @@ int uvc_status_init(struct uvc_device *dev) void uvc_status_unregister(struct uvc_device *dev) { - usb_kill_urb(dev->int_urb); + uvc_status_suspend(dev); uvc_input_unregister(dev); }