On Thu, Aug 07, 2025 at 08:00:06PM +0300, Laurent Pinchart wrote:
> On Thu, Aug 07, 2025 at 11:50:07AM +0300, Laurent Pinchart wrote:
> > On Wed, Aug 06, 2025 at 02:45:14PM +0200, Hans Verkuil wrote:
> > > On 02/08/2025 11:22, Jacopo Mondi wrote:
> > > > From: Laurent Pinchart <[email protected]>
> > > >
> > > > Multiple drivers that use v4l2_fh and call v4l2_fh_del() manually reset
> > > > the file->private_data pointer to NULL in their video device .release()
> > > > file operation handler. Move the code to the v4l2_fh_del() function to
> > > > avoid direct access to file->private_data in drivers. This requires
> > > > adding a file pointer argument to the function.
> > > >
> > > > Changes to drivers have been generated with the following coccinelle
> > > > semantic patch:
> > > >
> > > > @@
> > > > expression fh;
> > > > identifier filp;
> > > > identifier release;
> > > > type ret;
> > > > @@
> > > > ret release(..., struct file *filp, ...)
> > > > {
> > > > <...
> > > > - filp->private_data = NULL;
> > > > ...
> > > > - v4l2_fh_del(fh);
> > > > + v4l2_fh_del(fh, filp);
> > > > ...>
> > > > }
> > > >
> > > > @@
> > > > expression fh;
> > > > identifier filp;
> > > > identifier release;
> > > > type ret;
> > > > @@
> > > > ret release(..., struct file *filp, ...)
> > > > {
> > > > <...
> > > > - v4l2_fh_del(fh);
> > > > + v4l2_fh_del(fh, filp);
> > > > ...
> > > > - filp->private_data = NULL;
> > > > ...>
> > > > }
> > > >
> > > > @@
> > > > expression fh;
> > > > identifier filp;
> > > > identifier release;
> > > > type ret;
> > > > @@
> > > > ret release(..., struct file *filp, ...)
> > > > {
> > > > <...
> > > > - v4l2_fh_del(fh);
> > > > + v4l2_fh_del(fh, filp);
> > > > ...>
> > > > }
> > > >
> > > > Manual changes have been applied to Documentation/ to update the usage
> > > > patterns, to drivers/media/v4l2-core/v4l2-fh.c to update the
> > > > v4l2_fh_del() prototype and reset file->private_data, and to
> > > > include/media/v4l2-fh.h to update the v4l2_fh_del() function prototype
> > > > and its documentation.
> > > >
> > > > Additionally, white space issues have been fixed manually in
> > > > drivers/usb/gadget/function/uvc_v4l2.c
> > > >
> > > > Signed-off-by: Laurent Pinchart <[email protected]>
> > > > Signed-off-by: Jacopo Mondi <[email protected]>
> > > > ---
> > > > Documentation/driver-api/media/v4l2-fh.rst | 4
> > > > ++--
> > > > Documentation/translations/zh_CN/video4linux/v4l2-framework.txt | 4
> > > > ++--
> > > > drivers/media/pci/cx18/cx18-fileops.c | 4
> > > > ++--
> > > > drivers/media/pci/ivtv/ivtv-fileops.c | 4
> > > > ++--
> > > > drivers/media/pci/saa7164/saa7164-encoder.c | 2
> > > > +-
> > > > drivers/media/pci/saa7164/saa7164-vbi.c | 2
> > > > +-
> > > > drivers/media/platform/allegro-dvt/allegro-core.c | 2
> > > > +-
> > > > drivers/media/platform/amlogic/meson-ge2d/ge2d.c | 2
> > > > +-
> > > > drivers/media/platform/amphion/vpu_v4l2.c | 4
> > > > ++--
> > > > drivers/media/platform/chips-media/coda/coda-common.c | 4
> > > > ++--
> > > > drivers/media/platform/chips-media/wave5/wave5-helper.c | 2
> > > > +-
> > > > drivers/media/platform/imagination/e5010-jpeg-enc.c | 4
> > > > ++--
> > > > drivers/media/platform/m2m-deinterlace.c | 2
> > > > +-
> > > > drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c | 4
> > > > ++--
> > > > drivers/media/platform/mediatek/mdp/mtk_mdp_m2m.c | 4
> > > > ++--
> > > > drivers/media/platform/mediatek/mdp3/mtk-mdp3-m2m.c | 4
> > > > ++--
> > > > .../media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.c | 4
> > > > ++--
> > > > .../media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c | 4
> > > > ++--
> > > > drivers/media/platform/nvidia/tegra-vde/v4l2.c | 2
> > > > +-
> > > > drivers/media/platform/nxp/dw100/dw100.c | 2
> > > > +-
> > > > drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c | 4
> > > > ++--
> > > > drivers/media/platform/nxp/imx-pxp.c | 2
> > > > +-
> > > > drivers/media/platform/nxp/imx8-isi/imx8-isi-m2m.c | 2
> > > > +-
> > > > drivers/media/platform/nxp/mx2_emmaprp.c | 2
> > > > +-
> > > > drivers/media/platform/qcom/iris/iris_vidc.c | 3
> > > > +--
> > > > drivers/media/platform/qcom/venus/core.c | 2
> > > > +-
> > > > drivers/media/platform/renesas/rcar_fdp1.c | 2
> > > > +-
> > > > drivers/media/platform/renesas/rcar_jpu.c | 4
> > > > ++--
> > > > drivers/media/platform/renesas/vsp1/vsp1_video.c | 2
> > > > +-
> > > > drivers/media/platform/rockchip/rga/rga.c | 2
> > > > +-
> > > > drivers/media/platform/rockchip/rkvdec/rkvdec.c | 2
> > > > +-
> > > > drivers/media/platform/samsung/exynos-gsc/gsc-m2m.c | 4
> > > > ++--
> > > > drivers/media/platform/samsung/exynos4-is/fimc-m2m.c | 4
> > > > ++--
> > > > drivers/media/platform/samsung/s5p-g2d/g2d.c | 2
> > > > +-
> > > > drivers/media/platform/samsung/s5p-jpeg/jpeg-core.c | 4
> > > > ++--
> > > > drivers/media/platform/samsung/s5p-mfc/s5p_mfc.c | 4
> > > > ++--
> > > > drivers/media/platform/st/sti/bdisp/bdisp-v4l2.c | 4
> > > > ++--
> > > > drivers/media/platform/st/sti/delta/delta-v4l2.c | 4
> > > > ++--
> > > > drivers/media/platform/st/sti/hva/hva-v4l2.c | 4
> > > > ++--
> > > > drivers/media/platform/st/stm32/dma2d/dma2d.c | 2
> > > > +-
> > > > drivers/media/platform/sunxi/sun8i-di/sun8i-di.c | 2
> > > > +-
> > > > drivers/media/platform/sunxi/sun8i-rotate/sun8i_rotate.c | 2
> > > > +-
> > > > drivers/media/platform/ti/omap3isp/ispvideo.c | 5
> > > > ++---
> > > > drivers/media/platform/ti/vpe/vpe.c | 2
> > > > +-
> > > > drivers/media/platform/verisilicon/hantro_drv.c | 4
> > > > ++--
> > > > drivers/media/test-drivers/vicodec/vicodec-core.c | 2
> > > > +-
> > > > drivers/media/test-drivers/vim2m.c | 2
> > > > +-
> > > > drivers/media/test-drivers/visl/visl-core.c | 2
> > > > +-
> > > > drivers/media/usb/pvrusb2/pvrusb2-v4l2.c | 3
> > > > +--
> > > > drivers/media/v4l2-core/v4l2-fh.c | 7
> > > > ++++---
> > > > drivers/media/v4l2-core/v4l2-subdev.c | 5
> > > > ++---
> > > > drivers/staging/media/imx/imx-media-csc-scaler.c | 4
> > > > ++--
> > > > drivers/staging/media/meson/vdec/vdec.c | 2
> > > > +-
> > > > drivers/staging/media/sunxi/cedrus/cedrus.c | 2
> > > > +-
> > > > drivers/staging/most/video/video.c | 4
> > > > ++--
> > > > drivers/usb/gadget/function/uvc_v4l2.c | 3
> > > > +--
> > > > include/media/v4l2-fh.h | 5
> > > > ++++-
> > > > 57 files changed, 89 insertions(+), 90 deletions(-)
> > > >
> > >
> > > <snip>
> > >
> > > > diff --git a/drivers/media/v4l2-core/v4l2-fh.c
> > > > b/drivers/media/v4l2-core/v4l2-fh.c
> > > > index
> > > > b59b1084d8cdf1b62da12879e21dbe56c2109648..df3ba9d4674bd25626cfcddc2d0cb28c233e3cc3
> > > > 100644
> > > > --- a/drivers/media/v4l2-core/v4l2-fh.c
> > > > +++ b/drivers/media/v4l2-core/v4l2-fh.c
> > > > @@ -67,7 +67,7 @@ int v4l2_fh_open(struct file *filp)
> > > > }
> > > > EXPORT_SYMBOL_GPL(v4l2_fh_open);
> > > >
> > > > -void v4l2_fh_del(struct v4l2_fh *fh)
> > > > +void v4l2_fh_del(struct v4l2_fh *fh, struct file *filp)
> > >
> > > Instead of adding a second argument, perhaps it is better to
> > > just provide the filp pointer. After all, you can get the v4l2_fh
> > > from filp->private_data.
> > >
> > > It simplifies the code a bit.
> >
> > That's an interesting idea. I'll give it a try.
>
> We end up with code like (e.g. in v4l2_fh_release(), with similar
> constructs in lots of drivers)
>
> if (fh) {
> v4l2_fh_del(filp);
> v4l2_fh_exit(fh);
> kfree(fh);
> }
>
> compared to
>
> if (fh) {
> v4l2_fh_del(fh, filp);
> v4l2_fh_exit(fh);
> kfree(fh);
> }
>
> with the existing patch. I find the fact that v4l2_fh_del() takes a
> different pointer than v4l2_fh_exit() a bit disturbing. If you think
> it's better I'll drop the fh argument in v2.
I gave it a try, and looking at the function prototype, its
documentation, the imbalance with v4l2_fh_add(), and the code in the
callers, I think keeping both arguments would look cleaner. Please tell
me if you feel strongly about this, I can still submit a patch to drop
the argument. It can very easily be scripted with coccinelle and doesn't
conflict with the rest of the series, so it could also be done later.
> > > > {
> > > > unsigned long flags;
> > > >
> > > > @@ -75,6 +75,8 @@ void v4l2_fh_del(struct v4l2_fh *fh)
> > > > list_del_init(&fh->list);
> > > > spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
> > > > v4l2_prio_close(fh->vdev->prio, fh->prio);
> > > > +
> > > > + filp->private_data = NULL;
> > > > }
> > > > EXPORT_SYMBOL_GPL(v4l2_fh_del);
> > > >
> > > > @@ -94,10 +96,9 @@ int v4l2_fh_release(struct file *filp)
> > > > struct v4l2_fh *fh = file_to_v4l2_fh(filp);
> > > >
> > > > if (fh) {
> > > > - v4l2_fh_del(fh);
> > > > + v4l2_fh_del(fh, filp);
> > > > v4l2_fh_exit(fh);
> > > > kfree(fh);
> > > > - filp->private_data = NULL;
> > > > }
> > > > return 0;
> > > > }
> > >
> > > <snip>
> > >
> > > > diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h
> > > > index
> > > > d8fcf49f10e09452b73499f4a9bd1285bc2835a5..5e4c761635120608e0b588e0b0daf63e69588d38
> > > > 100644
> > > > --- a/include/media/v4l2-fh.h
> > > > +++ b/include/media/v4l2-fh.h
> > > > @@ -114,12 +114,15 @@ int v4l2_fh_open(struct file *filp);
> > > > * v4l2_fh_del - Remove file handle from the list of file handles.
> > > > *
> > > > * @fh: pointer to &struct v4l2_fh
> > > > + * @filp: pointer to &struct file associated with @fh
> > > > + *
> > > > + * The function resets filp->private_data to NULL.
> > > > *
> > > > * .. note::
> > > > * Must be called in v4l2_file_operations->release\(\) handler if
> > > > the driver
> > > > * uses &struct v4l2_fh.
> > > > */
> > > > -void v4l2_fh_del(struct v4l2_fh *fh);
> > > > +void v4l2_fh_del(struct v4l2_fh *fh, struct file *filp);
> > > >
> > > > /**
> > > > * v4l2_fh_exit - Release resources related to a file handle.
--
Regards,
Laurent Pinchart
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