Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Maxime Ripard <maxime@cerno.tech>
To:     dri-devel@lists.freedesktop.org,
        Daniel Vetter <daniel.vetter@intel.com>,
        David Airlie <airlied@linux.ie>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Maxime Ripard <maxime@cerno.tech>
Cc:     Emma Anholt <emma@anholt.net>,
        Hans Verkuil <hans.verkuil@cisco.com>,
        Daniel Vetter <daniel@ffwll.ch>, linux-kernel@vger.kernel.org,
        linux-rpi-kernel@lists.infradead.org,
        bcm-kernel-feedback-list@broadcom.com,
        Dave Stevenson <dave.stevenson@raspberrypi.com>,
        Phil Elwell <phil@raspberrypi.com>,
        Tim Gover <tim.gover@raspberrypi.com>,
        Dom Cobley <dom@raspberrypi.com>,
        Maxime Ripard <mripard@kernel.org>,
        Nicolas Saenz Julienne <nsaenz@kernel.org>
Subject: [PATCH 1/3] drm/vc4: hdmi: Drop devm interrupt handler for CEC interrupts
Date:   Wed,  7 Jul 2021 11:51:10 +0200
Message-Id: <20210707095112.1469670-2-maxime@cerno.tech>
In-Reply-To: <20210707095112.1469670-1-maxime@cerno.tech>
References: <20210707095112.1469670-1-maxime@cerno.tech>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The CEC interrupt handlers are registered through the
devm_request_threaded_irq function. However, while free_irq is indeed
called properly when the device is unbound or bind fails, it's called
after unbind or bind is done.

In our particular case, it means that on failure it creates a window
where our interrupt handler can be called, but we're freeing every
resource (CEC adapter, DRM objects, etc.) it might need.

In order to address this, let's switch to the non-devm variant to
control better when the handler will be unregistered and allow us to
make it safe.

Fixes: 15b4511a4af6 ("drm/vc4: add HDMI CEC support")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 49 +++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index cbeec6a5cb90..d966f61966c6 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1858,38 +1858,46 @@ static int vc4_hdmi_cec_init(struct vc4_hdmi *vc4_hdmi)
 	vc4_hdmi_cec_update_clk_div(vc4_hdmi);
 
 	if (vc4_hdmi->variant->external_irq_controller) {
-		ret = devm_request_threaded_irq(&pdev->dev,
-						platform_get_irq_byname(pdev, "cec-rx"),
-						vc4_cec_irq_handler_rx_bare,
-						vc4_cec_irq_handler_rx_thread, 0,
-						"vc4 hdmi cec rx", vc4_hdmi);
+		ret = request_threaded_irq(platform_get_irq_byname(pdev, "cec-rx"),
+					   vc4_cec_irq_handler_rx_bare,
+					   vc4_cec_irq_handler_rx_thread, 0,
+					   "vc4 hdmi cec rx", vc4_hdmi);
 		if (ret)
 			goto err_delete_cec_adap;
 
-		ret = devm_request_threaded_irq(&pdev->dev,
-						platform_get_irq_byname(pdev, "cec-tx"),
-						vc4_cec_irq_handler_tx_bare,
-						vc4_cec_irq_handler_tx_thread, 0,
-						"vc4 hdmi cec tx", vc4_hdmi);
+		ret = request_threaded_irq(platform_get_irq_byname(pdev, "cec-tx"),
+					   vc4_cec_irq_handler_tx_bare,
+					   vc4_cec_irq_handler_tx_thread, 0,
+					   "vc4 hdmi cec tx", vc4_hdmi);
 		if (ret)
-			goto err_delete_cec_adap;
+			goto err_remove_cec_rx_handler;
 	} else {
 		HDMI_WRITE(HDMI_CEC_CPU_MASK_SET, 0xffffffff);
 
-		ret = devm_request_threaded_irq(&pdev->dev, platform_get_irq(pdev, 0),
-						vc4_cec_irq_handler,
-						vc4_cec_irq_handler_thread, 0,
-						"vc4 hdmi cec", vc4_hdmi);
+		ret = request_threaded_irq(platform_get_irq(pdev, 0),
+					   vc4_cec_irq_handler,
+					   vc4_cec_irq_handler_thread, 0,
+					   "vc4 hdmi cec", vc4_hdmi);
 		if (ret)
 			goto err_delete_cec_adap;
 	}
 
 	ret = cec_register_adapter(vc4_hdmi->cec_adap, &pdev->dev);
 	if (ret < 0)
-		goto err_delete_cec_adap;
+		goto err_remove_handlers;
 
 	return 0;
 
+err_remove_handlers:
+	if (vc4_hdmi->variant->external_irq_controller)
+		free_irq(platform_get_irq_byname(pdev, "cec-tx"), vc4_hdmi);
+	else
+		free_irq(platform_get_irq(pdev, 0), vc4_hdmi);
+
+err_remove_cec_rx_handler:
+	if (vc4_hdmi->variant->external_irq_controller)
+		free_irq(platform_get_irq_byname(pdev, "cec-rx"), vc4_hdmi);
+
 err_delete_cec_adap:
 	cec_delete_adapter(vc4_hdmi->cec_adap);
 
@@ -1898,6 +1906,15 @@ static int vc4_hdmi_cec_init(struct vc4_hdmi *vc4_hdmi)
 
 static void vc4_hdmi_cec_exit(struct vc4_hdmi *vc4_hdmi)
 {
+	struct platform_device *pdev = vc4_hdmi->pdev;
+
+	if (vc4_hdmi->variant->external_irq_controller) {
+		free_irq(platform_get_irq_byname(pdev, "cec-rx"), vc4_hdmi);
+		free_irq(platform_get_irq_byname(pdev, "cec-tx"), vc4_hdmi);
+	} else {
+		free_irq(platform_get_irq(pdev, 0), vc4_hdmi);
+	}
+
 	cec_unregister_adapter(vc4_hdmi->cec_adap);
 }
 #else
-- 
2.31.1