Hi Nathan! On Wed, Sep 28, 2022 at 09:29:55AM -0700, Nathan Chancellor wrote:
On Wed, Sep 07, 2022 at 11:58:18PM +0200, Michael Grzeschik wrote:This patch is changing the simple workqueue in the gadget driver to be allocated as async_wq with a higher priority. The pump worker, that is filling the usb requests, will have a higher priority and will not be scheduled away so often while the video stream is handled. This will lead to fewer streaming underruns. Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>...diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h index 58e383afdd4406..1a31e6c6a5ffb8 100644 --- a/drivers/usb/gadget/function/uvc.h +++ b/drivers/usb/gadget/function/uvc.h @@ -88,6 +88,7 @@ struct uvc_video { struct usb_ep *ep; struct work_struct pump; + struct workqueue_struct *async_wq; /* Frame parameters */ u8 bpp;I am commenting here because this is the most recent change but after this showed up in -next as commit 9b91a6523078 ("usb: gadget: uvc: increase worker prio to WQ_HIGHPRI"), I see the following warning/error when building s390 allmodconfig: In file included from ../include/linux/string.h:253, from ../include/linux/bitmap.h:11, from ../include/linux/cpumask.h:12, from ../include/linux/smp.h:13, from ../include/linux/lockdep.h:14, from ../include/linux/rcupdate.h:29, from ../include/linux/rculist.h:11, from ../include/linux/pid.h:5, from ../include/linux/sched.h:14, from ../include/linux/ratelimit.h:6, from ../include/linux/dev_printk.h:16, from ../include/linux/device.h:15, from ../drivers/usb/gadget/function/f_uvc.c:9: In function ‘fortify_memset_chk’, inlined from ‘uvc_register_video’ at ../drivers/usb/gadget/function/f_uvc.c:424:2: ../include/linux/fortify-string.h:301:25: error: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning] 301 | __write_overflow_field(p_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This commit did not directly cause this, it just made the issue more obvious. In commit e4ce9ed835bc ("usb: gadget: uvc: ensure the vdev is unset"), also authored by you, the size parameter appears to be wrong? It is using the size of 'struct uvc_video', instead of the size of 'struct video_device'. It appears to be pure luck that everything worked up until this point, as those two types had the same size (1400 bytes) before this change but now 'struct uvc_video' is 1408 bytes, meaning there is now an overwrite. Any reason this is not the fix? Cheers, Nathan diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c index e6948cf8def3..836601227155 100644 --- a/drivers/usb/gadget/function/f_uvc.c +++ b/drivers/usb/gadget/function/f_uvc.c @@ -421,7 +421,7 @@ uvc_register_video(struct uvc_device *uvc) int ret; /* TODO reference counting. */ - memset(&uvc->vdev, 0, sizeof(uvc->video)); + memset(&uvc->vdev, 0, sizeof(uvc->vdev)); uvc->vdev.v4l2_dev = &uvc->v4l2_dev; uvc->vdev.v4l2_dev->dev = &cdev->gadget->dev; uvc->vdev.fops = &uvc_v4l2_fops;
This sounds right. Do you send a proper patch? Michael -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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