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Fri, 03 Apr 2026 07:55:16 -0700 (PDT) Date: Fri, 3 Apr 2026 16:55:14 +0200 From: Osama Abdelkader To: Luca Ceresoli Cc: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , =?iso-8859-1?Q?Andr=E9?= Almeida , Manikandan Muralidharan , Kees Cook , Heiko Stuebner , Andy Yan , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/bridge: dw-mipi-dsi: Fix bridge leak when host attach fails Message-ID: References: <20260402210054.42074-1-osama.abdelkader@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hello Luca, On Fri, Apr 03, 2026 at 08:50:29AM +0200, Luca Ceresoli wrote: > Hello Osama, > > On Thu Apr 2, 2026 at 11:00 PM CEST, Osama Abdelkader wrote: > > dw_mipi_dsi_host_attach() and dw_mipi_dsi2_host_attach() call > > drm_bridge_add() before pdata->host_ops->attach(). If attach fails, > > the bridge stayed registered without drm_bridge_remove(), leaking the > > bridge reference and leaving the device on the global bridge list. > > > > On failure, undo in the same order as host_detach(): for dw-mipi-dsi, > > drm_of_panel_bridge_remove() then drm_bridge_remove(); for dw-mipi-dsi2, > > drm_bridge_remove() then drm_of_panel_bridge_remove(). > > > > Fixes: 90910a651123 ("drm/bridge/synopsys: dsi: add ability to have glue-specific attach and detach") > > Fixes: 0d6d86253fef ("drm/bridge/synopsys: Add MIPI DSI2 host controller bridge") > > Signed-off-by: Osama Abdelkader > > --- > > drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 7 ++++++- > > drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi2.c | 7 ++++++- > > 2 files changed, 12 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c > > index ca4dea226f4b..ffa169c2de73 100644 > > --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c > > +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c > > @@ -345,10 +345,15 @@ static int dw_mipi_dsi_host_attach(struct mipi_dsi_host *host, > > if (pdata->host_ops && pdata->host_ops->attach) { > > ret = pdata->host_ops->attach(pdata->priv_data, device); > > if (ret < 0) > > - return ret; > > + goto err_remove_bridge; > > } > > > > return 0; > > + > > +err_remove_bridge: > > + drm_of_panel_bridge_remove(host->dev->of_node, 1, 0); > > It was added by a devm_action, you shouldn't remove it here. Besides, > devm_drm_of_get_bridge() might return A) a panel_bridge or B) a pointer to > another, pre-existing bridge (and the called can't know which one got > returned). drm_of_panel_bridge_remove() unconditionally removes a > panel_bridge so it's wrong in case B. > > Which means the drm_of_panel_bridge_remove() in _host_detach is probably > wrong and you should look at it. > > > + drm_bridge_remove(&dsi->bridge); Thanks for the information, I'm going to look at it in another patch. > > This is correct, even though using devm_drm_bridge_add() instead of > drm_bridge_add() above is probably the simplest solution. > > Same for the other driver in this patch. Thank you, I just did that in v2. Thanks, Osama > > Luca > > -- > Luca Ceresoli, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com