The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x ba4fafb02ad6a4eb2e00f861893b5db42ba54369 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025062032-omnivore-overcook-a17c@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ba4fafb02ad6a4eb2e00f861893b5db42ba54369 Mon Sep 17 00:00:00 2001 From: Ricardo Ribalda ribalda@chromium.org Date: Mon, 24 Feb 2025 10:34:53 +0000 Subject: [PATCH] media: uvcvideo: Return the number of processed controls

If we let know our callers that we have not done anything, they will be able to optimize their decisions.

Cc: stable@kernel.org Fixes: b4012002f3a3 ("[media] uvcvideo: Add support for control events") Reviewed-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Ricardo Ribalda ribalda@chromium.org Message-ID: 20250224-uvc-data-backup-v2-1-de993ed9823b@chromium.org Signed-off-by: Hans de Goede hdegoede@redhat.com Signed-off-by: Hans Verkuil hverkuil@xs4all.nl

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c index e2052130f4c9..0c4d84eab42a 100644 --- a/drivers/media/usb/uvc/uvc_ctrl.c +++ b/drivers/media/usb/uvc/uvc_ctrl.c @@ -2101,12 +2101,17 @@ int uvc_ctrl_begin(struct uvc_video_chain *chain) return mutex_lock_interruptible(&chain->ctrl_mutex) ? -ERESTARTSYS : 0; }

+/* + * Returns the number of uvc controls that have been correctly set, or a + * negative number if there has been an error. + */ static int uvc_ctrl_commit_entity(struct uvc_device *dev, struct uvc_fh *handle, struct uvc_entity *entity, int rollback, struct uvc_control **err_ctrl) { + unsigned int processed_ctrls = 0; struct uvc_control *ctrl; unsigned int i; int ret; @@ -2141,6 +2146,9 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev, else ret = 0;

+ if (!ret) + processed_ctrls++; + if (rollback || ret < 0) memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT), uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP), @@ -2159,7 +2167,7 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev, } }

- return 0; + return processed_ctrls; }

static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity, @@ -2206,6 +2214,7 @@ int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,

if (!rollback) uvc_ctrl_send_events(handle, ctrls->controls, ctrls->count); + ret = 0; done: mutex_unlock(&chain->ctrl_mutex); return ret;