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Tue, 24 Dec 2024 15:10:27 -0800 (PST) From: Dmitry Baryshkov Date: Wed, 25 Dec 2024 01:10:13 +0200 Subject: [PATCH RFC/RFT 5/9] drm/vc4: hdmi: drop separate CEC unregistration 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="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20241225-drm-hdmi-connector-cec-v1-5-b80380c67221@linaro.org> References: <20241225-drm-hdmi-connector-cec-v1-0-b80380c67221@linaro.org> In-Reply-To: <20241225-drm-hdmi-connector-cec-v1-0-b80380c67221@linaro.org> To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Dave Stevenson , =?utf-8?q?Ma=C3=ADra_Canal?= , Raspberry Pi Kernel Maintenance , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3327; i=dmitry.baryshkov@linaro.org; h=from:subject:message-id; bh=bpU/QTzs/6e35Bs6BI4kFzNjxwYaRMD/cnt3/GPJ2Gc=; b=owGbwMvMwMXYbdNlx6SpcZXxtFoSQ3q2fWhpzI+yzW89hZV2uz5qz/xw+5u+yrIJn75LxgcF3 U4/6LCuk9GYhYGRi0FWTJHFp6Blasym5LAPO6bWwwxiZQKZwsDFKQAT+XyN/Z+VcF/BYY0t5Rre a57rHwxZsEp5yYupEcHHj4nent/NHdIaqsT9fl3bqYjbB4r4nGIeWjBEW9zQdorKOptrw7XVYFv ltry/6Y7B9zvuL+142RlQWeb/4vX/IDfzq+FXFbQbj3QuecP/5FiH57ON+ftvGy7p0+3l6hZYa/ zz+CO2902zmFeaT1vkt25hyIM2zjupQVNtts8RPCZToGtZ7lRZw/qEv0XeVjrUtMOfTeq3XklT7 LbnL9Vyeduj9bSunwi0tg/QOLH64jW5Jba9h1pnCOq5ep9fb2zXG39XNWzaLG8Ls+55y3OVZFwn T2PfeZypwMhGzSxJndVdNjde6VHDMwfHr3nzQlKTIrYBAA== X-Developer-Key: i=dmitry.baryshkov@linaro.org; a=openpgp; fpr=8F88381DD5C873E4AE487DA5199BF1243632046A CEC adapter functions are protected by drm_dev_enter() / _exit(), so it is safe to keep CEC registered until DRM device is being torn down. Drop custom CEC unsregistration code and rely on the DRM core to unregister CEC adapter. Signed-off-by: Dmitry Baryshkov --- drivers/gpu/drm/vc4/vc4_hdmi.c | 53 ++++++--------------------------------= ---- 1 file changed, 7 insertions(+), 46 deletions(-) diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 3086c2ad3bb2e8fafdc1f37ba985aa5785d49f9a..7b39000369e50f5368384575aa8= 1919df5a7133c 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -2752,13 +2752,6 @@ static const struct cec_adap_ops vc4_hdmi_cec_adap_o= ps =3D { .adap_transmit =3D vc4_hdmi_cec_adap_transmit, }; =20 -static void vc4_hdmi_cec_release(void *ptr) -{ - struct drm_connector *connector =3D ptr; - - drm_connector_cec_unregister(connector); -} - static int vc4_hdmi_cec_init(struct drm_connector *connector) { struct vc4_hdmi *vc4_hdmi =3D connector_to_vc4_hdmi(connector); @@ -2796,51 +2789,19 @@ static int vc4_hdmi_cec_register(struct vc4_hdmi *v= c4_hdmi) { struct platform_device *pdev =3D vc4_hdmi->pdev; struct device *dev =3D &pdev->dev; - int ret; =20 if (!of_property_present(dev->of_node, "interrupts")) { dev_warn(dev, "'interrupts' DT property is missing, no CEC\n"); return 0; } =20 - ret =3D drm_connector_hdmi_cec_adapter_register(&vc4_hdmi->connector, - &vc4_hdmi_cec_adap_ops, - vc4_hdmi->variant->card_name, - 1, - vc4_hdmi_cec_init, - NULL, - &pdev->dev); - if (ret < 0) - return ret; - - /* - * NOTE: Strictly speaking, we should probably use a DRM-managed - * registration there to avoid removing the CEC adapter by the - * time the DRM driver doesn't have any user anymore. - * - * However, the CEC framework already cleans up the CEC adapter - * only when the last user has closed its file descriptor, so we - * don't need to handle it in DRM. - * - * By the time the device-managed hook is executed, we will give - * up our reference to the CEC adapter and therefore don't - * really care when it's actually freed. - * - * There's still a problematic sequence: if we unregister our - * CEC adapter, but the userspace keeps a handle on the CEC - * adapter but not the DRM device for some reason. In such a - * case, our vc4_hdmi structure will be freed, but the - * cec_adapter structure will have a dangling pointer to what - * used to be our HDMI controller. If we get a CEC call at that - * moment, we could end up with a use-after-free. Fortunately, - * the CEC framework already handles this too, by calling - * cec_is_registered() in cec_ioctl() and cec_poll(). - */ - ret =3D devm_add_action_or_reset(dev, vc4_hdmi_cec_release, vc4_hdmi); - if (ret) - return ret; - - return 0; + return drm_connector_hdmi_cec_adapter_register(&vc4_hdmi->connector, + &vc4_hdmi_cec_adap_ops, + vc4_hdmi->variant->card_name, + 1, + vc4_hdmi_cec_init, + NULL, + &pdev->dev); } #else static int vc4_hdmi_cec_register(struct vc4_hdmi *vc4_hdmi) --=20 2.39.5