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([2a01:e0a:90c:e290:1062:9531:8150:c5f3]) by smtp.gmail.com with ESMTPSA id h14sm1932369wmb.1.2021.05.25.00.27.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 25 May 2021 00:27:12 -0700 (PDT) Subject: Re: [PATCH] drm/meson: fix shutdown crash when component not probed To: dri-devel@lists.freedesktop.org Cc: linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Stefan Agner References: <20210430082744.3638743-1-narmstrong@baylibre.com> From: Neil Armstrong Organization: Baylibre Message-ID: <0359d826-49d5-d724-b38e-012e3389ae43@baylibre.com> Date: Tue, 25 May 2021 09:27:11 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210430082744.3638743-1-narmstrong@baylibre.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30/04/2021 10:27, Neil Armstrong wrote: > When main component is not probed, by example when the dw-hdmi module is > not loaded yet or in probe defer, the following crash appears on shutdown: > > Unable to handle kernel NULL pointer dereference at virtual address 0000000000000038 > ... > pc : meson_drv_shutdown+0x24/0x50 > lr : platform_drv_shutdown+0x20/0x30 > ... > Call trace: > meson_drv_shutdown+0x24/0x50 > platform_drv_shutdown+0x20/0x30 > device_shutdown+0x158/0x360 > kernel_restart_prepare+0x38/0x48 > kernel_restart+0x18/0x68 > __do_sys_reboot+0x224/0x250 > __arm64_sys_reboot+0x24/0x30 > ... > > Simply check if the priv struct has been allocated before using it. > > Fixes: fa0c16caf3d7 ("drm: meson_drv add shutdown function") > Reported-by: Stefan Agner > Signed-off-by: Neil Armstrong > --- > drivers/gpu/drm/meson/meson_drv.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c > index 453d8b4c5763..07fcd12dca16 100644 > --- a/drivers/gpu/drm/meson/meson_drv.c > +++ b/drivers/gpu/drm/meson/meson_drv.c > @@ -485,11 +485,12 @@ static int meson_probe_remote(struct platform_device *pdev, > static void meson_drv_shutdown(struct platform_device *pdev) > { > struct meson_drm *priv = dev_get_drvdata(&pdev->dev); > - struct drm_device *drm = priv->drm; > > - DRM_DEBUG_DRIVER("\n"); > - drm_kms_helper_poll_fini(drm); > - drm_atomic_helper_shutdown(drm); > + if (!priv) > + return; > + > + drm_kms_helper_poll_fini(priv->drm); > + drm_atomic_helper_shutdown(priv->drm); > } > > static int meson_drv_probe(struct platform_device *pdev) > Applied to drm-misc-fixes Neil