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(dynamic-2a02-3100-a029-9600-b581-b80a-431b-19ed.310.pool.telefonica.de. [2a02:3100:a029:9600:b581:b80a:431b:19ed]) by smtp.googlemail.com with ESMTPSA id a640c23a62f3a-a9e564e8ea1sm347691466b.92.2024.11.02.14.33.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 02 Nov 2024 14:33:25 -0700 (PDT) Message-ID: Date: Sat, 2 Nov 2024 22:33:24 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/6] drm: Change drm_class from pointer to const struct class To: Dmitry Baryshkov , Greg Kroah-Hartman , "Rafael J. Wysocki" Cc: Oded Gabbay , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Hans de Goede , "open list:AMD KFD" References: <499229fd-5344-4799-85bf-93e4b3b45eca@gmail.com> <9e5567f6-c27e-4875-9db8-0435669a7d7c@gmail.com> <56lilw7gkq4ggtxfoykxcd727llmdrc2wksoafhjktxwpxil4e@6kcfqgwtxcrj> Content-Language: en-US From: Heiner Kallweit Autocrypt: addr=hkallweit1@gmail.com; keydata= xsFNBF/0ZFUBEAC0eZyktSE7ZNO1SFXL6cQ4i4g6Ah3mOUIXSB4pCY5kQ6OLKHh0FlOD5/5/ sY7IoIouzOjyFdFPnz4Bl3927ClT567hUJJ+SNaFEiJ9vadI6vZm2gcY4ExdIevYHWe1msJF MVE4yNwdS+UsPeCF/6CQQTzHc+n7DomE7fjJD5J1hOJjqz2XWe71fTvYXzxCFLwXXbBiqDC9 dNqOe5odPsa4TsWZ09T33g5n2nzTJs4Zw8fCy8rLqix/raVsqr8fw5qM66MVtdmEljFaJ9N8 /W56qGCp+H8Igk/F7CjlbWXiOlKHA25mPTmbVp7VlFsvsmMokr/imQr+0nXtmvYVaKEUwY2g 86IU6RAOuA8E0J5bD/BeyZdMyVEtX1kT404UJZekFytJZrDZetwxM/cAH+1fMx4z751WJmxQ J7mIXSPuDfeJhRDt9sGM6aRVfXbZt+wBogxyXepmnlv9K4A13z9DVLdKLrYUiu9/5QEl6fgI kPaXlAZmJsQfoKbmPqCHVRYj1lpQtDM/2/BO6gHASflWUHzwmBVZbS/XRs64uJO8CB3+V3fa cIivllReueGCMsHh6/8wgPAyopXOWOxbLsZ291fmZqIR0L5Y6b2HvdFN1Xhc+YrQ8TKK+Z4R mJRDh0wNQ8Gm89g92/YkHji4jIWlp2fwzCcx5+lZCQ1XdqAiHQARAQABzSZIZWluZXIgS2Fs bHdlaXQgPGhrYWxsd2VpdDFAZ21haWwuY29tPsLBjgQTAQgAOBYhBGxfqY/yOyXjyjJehXLe ig9U8DoMBQJf9GRVAhsDBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAAAoJEHLeig9U8DoMSycQ AJbfg8HZEK0ljV4M8nvdaiNixWAufrcZ+SD8zhbxl8GispK4F3Yo+20Y3UoZ7FcIidJWUUJL axAOkpI/70YNhlqAPMsuudlAieeYZKjIv1WV5ucNZ3VJ7dC+dlVqQdAr1iD869FZXvy91KhJ wYulyCf+s4T9YgmLC6jLMBZghKIf1uhSd0NzjyCqYWbk2ZxByZHgunEShOhHPHswu3Am0ftt ePaYIHgZs+Vzwfjs8I7EuW/5/f5G9w1vibXxtGY/GXwgGGHRDjFM7RSprGOv4F5eMGh+NFUJ TU9N96PQYMwXVxnQfRXl8O6ffSVmFx4H9rovxWPKobLmqQL0WKLLVvA/aOHCcMKgfyKRcLah 57vGC50Ga8oT2K1g0AhKGkyJo7lGXkMu5yEs0m9O+btqAB261/E3DRxfI1P/tvDZpLJKtq35 dXsj6sjvhgX7VxXhY1wE54uqLLHY3UZQlmH3QF5t80MS7/KhxB1pO1Cpcmkt9hgyzH8+5org +9wWxGUtJWNP7CppY+qvv3SZtKJMKsxqk5coBGwNkMms56z4qfJm2PUtJQGjA65XWdzQACib 2iaDQoBqGZfXRdPT0tC1H5kUJuOX4ll1hI/HBMEFCcO8++Bl2wcrUsAxLzGvhINVJX2DAQaF aNetToazkCnzubKfBOyiTqFJ0b63c5dqziAgzsFNBF/0ZFUBEADF8UEZmKDl1w/UxvjeyAeX kghYkY3bkK6gcIYXdLRfJw12GbvMioSguvVzASVHG8h7NbNjk1yur6AONfbUpXKSNZ0skV8V fG+ppbaY+zQofsSMoj5gP0amwbwvPzVqZCYJai81VobefTX2MZM2Mg/ThBVtGyzV3NeCpnBa 8AX3s9rrX2XUoCibYotbbxx9afZYUFyflOc7kEpc9uJXIdaxS2Z6MnYLHsyVjiU6tzKCiVOU KJevqvzPXJmy0xaOVf7mhFSNQyJTrZpLa+tvB1DQRS08CqYtIMxRrVtC0t0LFeQGly6bOngr ircurWJiJKbSXVstLHgWYiq3/GmCSx/82ObeLO3PftklpRj8d+kFbrvrqBgjWtMH4WtK5uN5 1WJ71hWJfNchKRlaJ3GWy8KolCAoGsQMovn/ZEXxrGs1ndafu47yXOpuDAozoHTBGvuSXSZo ythk/0EAuz5IkwkhYBT1MGIAvNSn9ivE5aRnBazugy0rTRkVggHvt3/7flFHlGVGpBHxFUwb /a4UjJBPtIwa4tWR8B1Ma36S8Jk456k2n1id7M0LQ+eqstmp6Y+UB+pt9NX6t0Slw1NCdYTW gJezWTVKF7pmTdXszXGxlc9kTrVUz04PqPjnYbv5UWuDd2eyzGjrrFOsJEi8OK2d2j4FfF++ AzOMdW09JVqejQARAQABwsF2BBgBCAAgFiEEbF+pj/I7JePKMl6Fct6KD1TwOgwFAl/0ZFUC GwwACgkQct6KD1TwOgxUfg//eAoYc0Vm4NrxymfcY30UjHVD0LgSvU8kUmXxil3qhFPS7KA+ y7tgcKLHOkZkXMX5MLFcS9+SmrAjSBBV8omKoHNo+kfFx/dUAtz0lot8wNGmWb+NcHeKM1eb nwUMOEa1uDdfZeKef/U/2uHBceY7Gc6zPZPWgXghEyQMTH2UhLgeam8yglyO+A6RXCh+s6ak Wje7Vo1wGK4eYxp6pwMPJXLMsI0ii/2k3YPEJPv+yJf90MbYyQSbkTwZhrsokjQEaIfjrIk3 rQRjTve/J62WIO28IbY/mENuGgWehRlTAbhC4BLTZ5uYS0YMQCR7v9UGMWdNWXFyrOB6PjSu Trn9MsPoUc8qI72mVpxEXQDLlrd2ijEWm7Nrf52YMD7hL6rXXuis7R6zY8WnnBhW0uCfhajx q+KuARXC0sDLztcjaS3ayXonpoCPZep2Bd5xqE4Ln8/COCslP7E92W1uf1EcdXXIrx1acg21 H/0Z53okMykVs3a8tECPHIxnre2UxKdTbCEkjkR4V6JyplTS47oWMw3zyI7zkaadfzVFBxk2 lo/Tny+FX1Azea3Ce7oOnRUEZtWSsUidtIjmL8YUQFZYm+JUIgfRmSpMFq8JP4VH43GXpB/S OCrl+/xujzvoUBFV/cHKjEQYBxo+MaiQa1U54ykM2W4DnHb1UiEf5xDkFd4= In-Reply-To: <56lilw7gkq4ggtxfoykxcd727llmdrc2wksoafhjktxwpxil4e@6kcfqgwtxcrj> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 22.09.2024 17:11, Dmitry Baryshkov wrote: > On Sun, Sep 08, 2024 at 02:11:25PM GMT, Heiner Kallweit wrote: >> Define class drm statically and constify it. This ensure that no user >> of the exported struct class can tamper with it. >> >> Signed-off-by: Heiner Kallweit >> --- >> drivers/gpu/drm/drm_internal.h | 2 +- >> drivers/gpu/drm/drm_privacy_screen.c | 2 +- >> drivers/gpu/drm/drm_sysfs.c | 32 ++++++++++++++-------------- >> 3 files changed, 18 insertions(+), 18 deletions(-) >> >> diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h >> index 1705bfc90..6e0df44b6 100644 >> --- a/drivers/gpu/drm/drm_internal.h >> +++ b/drivers/gpu/drm/drm_internal.h >> @@ -139,7 +139,7 @@ bool drm_master_internal_acquire(struct drm_device *dev); >> void drm_master_internal_release(struct drm_device *dev); >> >> /* drm_sysfs.c */ >> -extern struct class *drm_class; >> +extern const struct class drm_class; >> >> int drm_sysfs_init(void); >> void drm_sysfs_destroy(void); >> diff --git a/drivers/gpu/drm/drm_privacy_screen.c b/drivers/gpu/drm/drm_privacy_screen.c >> index 6cc39e307..2fbd24ba5 100644 >> --- a/drivers/gpu/drm/drm_privacy_screen.c >> +++ b/drivers/gpu/drm/drm_privacy_screen.c >> @@ -401,7 +401,7 @@ struct drm_privacy_screen *drm_privacy_screen_register( >> mutex_init(&priv->lock); >> BLOCKING_INIT_NOTIFIER_HEAD(&priv->notifier_head); >> >> - priv->dev.class = drm_class; >> + priv->dev.class = &drm_class; >> priv->dev.type = &drm_privacy_screen_type; >> priv->dev.parent = parent; >> priv->dev.release = drm_privacy_screen_device_release; >> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c >> index f8577043e..f443f9a76 100644 >> --- a/drivers/gpu/drm/drm_sysfs.c >> +++ b/drivers/gpu/drm/drm_sysfs.c >> @@ -58,7 +58,15 @@ static struct device_type drm_sysfs_device_connector = { >> .name = "drm_connector", >> }; >> >> -struct class *drm_class; >> +static char *drm_devnode(const struct device *dev, umode_t *mode) >> +{ >> + return kasprintf(GFP_KERNEL, "dri/%s", dev_name(dev)); >> +} >> + >> +const struct class drm_class = { >> + .name = "drm", >> + .devnode = drm_devnode, >> +}; >> >> #ifdef CONFIG_ACPI >> static bool drm_connector_acpi_bus_match(struct device *dev) >> @@ -93,11 +101,6 @@ static void drm_sysfs_acpi_register(void) { } >> static void drm_sysfs_acpi_unregister(void) { } >> #endif >> >> -static char *drm_devnode(const struct device *dev, umode_t *mode) >> -{ >> - return kasprintf(GFP_KERNEL, "dri/%s", dev_name(dev)); >> -} >> - > > Please keep this function in place and move drm_class declarattion next > to it. It simplifies reviewing the code. > >> static int typec_connector_bind(struct device *dev, >> struct device *typec_connector, void *data) >> { >> @@ -138,14 +141,12 @@ static const struct component_ops typec_connector_ops = { >> */ >> int drm_sysfs_init(void) >> { >> - drm_class = class_create("drm"); >> - if (IS_ERR(drm_class)) >> - return PTR_ERR(drm_class); >> + int ret = class_register(&drm_class); >> >> - drm_class->devnode = drm_devnode; >> + if (!ret) >> + drm_sysfs_acpi_register(); >> >> - drm_sysfs_acpi_register(); >> - return 0; >> + return ret; >> } >> >> /** >> @@ -156,8 +157,7 @@ int drm_sysfs_init(void) >> void drm_sysfs_destroy(void) >> { >> drm_sysfs_acpi_unregister(); >> - class_destroy(drm_class); >> - drm_class = NULL; >> + class_unregister(&drm_class); > > This code makes me wonder: can we define static classes in unloadable > modules? What happens if userspace holds the reference on the class in > sysfs, while we remove the module ? > I'm not sure, just saw that this isn't an unusual scenario. Let's ask the drivers/base maintainers. +Greg/Rafael >> } >> >> static void drm_sysfs_release(struct device *dev) >> @@ -337,7 +337,7 @@ int drm_sysfs_connector_add(struct drm_connector *connector) >> return -ENOMEM; >> >> device_initialize(kdev); >> - kdev->class = drm_class; >> + kdev->class = &drm_class; >> kdev->type = &drm_sysfs_device_connector; >> kdev->parent = dev->primary->kdev; >> kdev->groups = connector_dev_groups; >> @@ -516,7 +516,7 @@ struct device *drm_sysfs_minor_alloc(struct drm_minor *minor) >> minor_str = "card%d"; >> >> kdev->devt = MKDEV(DRM_MAJOR, minor->index); >> - kdev->class = drm_class; >> + kdev->class = &drm_class; >> kdev->type = &drm_sysfs_device_minor; >> } >> >> -- >> 2.46.0 >> >> >