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Message-ID: <20250807170004.GG11583@pendragon.ideasonboard.com>
Date: Thu, 7 Aug 2025 20:00:04 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Hans Verkuil <hverkuil+cisco@...nel.org>
Cc: Jacopo Mondi <jacopo.mondi@...asonboard.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Devarsh Thakkar <devarsht@...com>, Benoit Parrot <bparrot@...com>,
Hans Verkuil <hverkuil@...nel.org>, Mike Isely <isely@...ox.com>,
Hans de Goede <hansg@...nel.org>,
Parthiban Veerasooran <parthiban.veerasooran@...rochip.com>,
Christian Gromm <christian.gromm@...rochip.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Alex Shi <alexs@...nel.org>, Yanteng Si <si.yanteng@...ux.dev>,
Dongliang Mu <dzm91@...t.edu.cn>, Jonathan Corbet <corbet@....net>,
Tomasz Figa <tfiga@...omium.org>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Andy Walls <awalls@...metrocast.net>,
Michael Tretter <m.tretter@...gutronix.de>,
Pengutronix Kernel Team <kernel@...gutronix.de>,
Bin Liu <bin.liu@...iatek.com>,
Matthias Brugger <matthias.bgg@...il.com>,
AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
Dmitry Osipenko <digetx@...il.com>,
Thierry Reding <thierry.reding@...il.com>,
Jonathan Hunter <jonathanh@...dia.com>,
Mirela Rabulea <mirela.rabulea@....com>,
Shawn Guo <shawnguo@...nel.org>,
Sascha Hauer <s.hauer@...gutronix.de>,
Fabio Estevam <festevam@...il.com>,
Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
Michal Simek <michal.simek@....com>, Ming Qian <ming.qian@....com>,
Zhou Peng <eagle.zhou@....com>,
Xavier Roumegue <xavier.roumegue@....nxp.com>,
Philipp Zabel <p.zabel@...gutronix.de>,
Vikash Garodia <quic_vgarodia@...cinc.com>,
Dikshita Agarwal <quic_dikshita@...cinc.com>,
Abhinav Kumar <abhinav.kumar@...ux.dev>,
Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
Sylwester Nawrocki <sylvester.nawrocki@...il.com>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Chen-Yu Tsai <wens@...e.org>, Samuel Holland <samuel@...lland.org>,
Daniel Almeida <daniel.almeida@...labora.com>,
Neil Armstrong <neil.armstrong@...aro.org>,
Kevin Hilman <khilman@...libre.com>,
Jerome Brunet <jbrunet@...libre.com>,
Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
Nas Chung <nas.chung@...psnmedia.com>,
Jackson Lee <jackson.lee@...psnmedia.com>,
Minghsiu Tsai <minghsiu.tsai@...iatek.com>,
Houlong Wei <houlong.wei@...iatek.com>,
Andrew-CT Chen <andrew-ct.chen@...iatek.com>,
Tiffany Lin <tiffany.lin@...iatek.com>,
Yunfei Dong <yunfei.dong@...iatek.com>,
Geert Uytterhoeven <geert+renesas@...der.be>,
Magnus Damm <magnus.damm@...il.com>,
Mikhail Ulyanov <mikhail.ulyanov@...entembedded.com>,
Jacob Chen <jacob-chen@...wrt.com>,
Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
Heiko Stuebner <heiko@...ech.de>,
Detlev Casanova <detlev.casanova@...labora.com>,
Krzysztof Kozlowski <krzk@...nel.org>,
Alim Akhtar <alim.akhtar@...sung.com>,
Sylwester Nawrocki <s.nawrocki@...sung.com>,
Łukasz Stelmach <l.stelmach@...sung.com>,
Andrzej Pietrasiewicz <andrzejtp2010@...il.com>,
Jacek Anaszewski <jacek.anaszewski@...il.com>,
Andrzej Hajda <andrzej.hajda@...el.com>,
Fabien Dessenne <fabien.dessenne@...s.st.com>,
Hugues Fruchet <hugues.fruchet@...s.st.com>,
Jean-Christophe Trotin <jean-christophe.trotin@...s.st.com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>,
Nicolas Dufresne <nicolas.dufresne@...labora.com>,
Benjamin Gaignard <benjamin.gaignard@...labora.com>,
Steve Longerbeam <slongerbeam@...il.com>,
Maxime Ripard <mripard@...nel.org>,
Paul Kocialkowski <paulk@...-base.io>,
Niklas Söderlund <niklas.soderlund@...natech.se>,
Robert Foss <rfoss@...nel.org>, Todor Tomov <todor.too@...il.com>,
Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>,
Corentin Labbe <clabbe@...libre.com>,
Sakari Ailus <sakari.ailus@...ux.intel.com>,
Bingbu Cao <bingbu.cao@...el.com>,
Tianshu Qiu <tian.shu.qiu@...el.com>,
Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>,
linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-staging@...ts.linux.dev, linux-doc@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org, linux-tegra@...r.kernel.org,
imx@...ts.linux.dev, linux-renesas-soc@...r.kernel.org,
linux-arm-msm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
linux-sunxi@...ts.linux.dev, linux-usb@...r.kernel.org,
linux-amlogic@...ts.infradead.org,
linux-rockchip@...ts.infradead.org,
linux-stm32@...md-mailman.stormreply.com,
mjpeg-users@...ts.sourceforge.net
Subject: Re: [PATCH 27/65] media: Reset file->private_data to NULL in
v4l2_fh_del()
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 <laurent.pinchart@...asonboard.com>
> > >
> > > 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 <laurent.pinchart@...asonboard.com>
> > > Signed-off-by: Jacopo Mondi <jacopo.mondi@...asonboard.com>
> > > ---
> > > 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.
> > > {
> > > 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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