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b=aW6JtiQ2/8Hfpq3R5Kl9ViTTqFaBbWQnRGDqk2G/G2RnJfHu6Pt/0jkrXy1vWhYFF rW2JzUMUG1eq+u0S3BS8urig9CSDZiqXutOKIKblGLko41IDQcwQOwFNODkRGwRix6 gxhAuEzBuWlII8bO++3bbYIixr3rqneaI1t4QCzY= Date: Thu, 7 Aug 2025 23:25:53 +0300 From: Laurent Pinchart To: Hans Verkuil Cc: Jacopo Mondi , Mauro Carvalho Chehab , Devarsh Thakkar , Benoit Parrot , Hans Verkuil , Mike Isely , Hans de Goede , Parthiban Veerasooran , Christian Gromm , Greg Kroah-Hartman , Alex Shi , Yanteng Si , Dongliang Mu , Jonathan Corbet , Tomasz Figa , Marek Szyprowski , Andy Walls , Michael Tretter , Pengutronix Kernel Team , Bin Liu , Matthias Brugger , AngeloGioacchino Del Regno , Dmitry Osipenko , Thierry Reding , Jonathan Hunter , Mirela Rabulea , Shawn Guo , Sascha Hauer , Fabio Estevam , Kieran Bingham , Michal Simek , Ming Qian , Zhou Peng , Xavier Roumegue , Philipp Zabel , Vikash Garodia , Dikshita Agarwal , Abhinav Kumar , Bryan O'Donoghue , Sylwester Nawrocki , Jernej Skrabec , Chen-Yu Tsai , Samuel Holland , Daniel Almeida , Neil Armstrong , Kevin Hilman , Jerome Brunet , Martin Blumenstingl , Nas Chung , Jackson Lee , Minghsiu Tsai , Houlong Wei , Andrew-CT Chen , Tiffany Lin , Yunfei Dong , Geert Uytterhoeven , Magnus Damm , Mikhail Ulyanov , Jacob Chen , Ezequiel Garcia , Heiko Stuebner , Detlev Casanova , Krzysztof Kozlowski , Alim Akhtar , Sylwester Nawrocki , =?utf-8?Q?=C5=81ukasz?= Stelmach , Andrzej Pietrasiewicz , Jacek Anaszewski , Andrzej Hajda , Fabien Dessenne , Hugues Fruchet , Jean-Christophe Trotin , Maxime Coquelin , Alexandre Torgue , Nicolas Dufresne , Benjamin Gaignard , Steve Longerbeam , Maxime Ripard , Paul Kocialkowski , Niklas =?utf-8?Q?S=C3=B6derlund?= , Robert Foss , Todor Tomov , Vladimir Zapolskiy , Corentin Labbe , Sakari Ailus , Bingbu Cao , Tianshu Qiu , Stanislaw Gruszka , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-staging@lists.linux.dev, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-tegra@vger.kernel.org, imx@lists.linux.dev, linux-renesas-soc@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-sunxi@lists.linux.dev, linux-usb@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-stm32@st-md-mailman.stormreply.com, mjpeg-users@lists.sourceforge.net Subject: Re: [PATCH 27/65] media: Reset file->private_data to NULL in v4l2_fh_del() Message-ID: <20250807202553.GB28610@pendragon.ideasonboard.com> References: <20250802-media-private-data-v1-0-eb140ddd6a9d@ideasonboard.com> <20250802-media-private-data-v1-27-eb140ddd6a9d@ideasonboard.com> <20250807085003.GE11583@pendragon.ideasonboard.com> <20250807170004.GG11583@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250807170004.GG11583@pendragon.ideasonboard.com> 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 > > > > > > > > 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 > > > > Signed-off-by: Jacopo Mondi > > > > --- > > > > 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(-) > > > > > > > > > > > > > > > > > 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; > > > > } > > > > > > > > > > > > > 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