Received-SPF: pass (google.com: domain of linux-crypto+bounces-3073-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Date: Fri, 29 Mar 2024 12:42:08 +0100
From: Stefano Garzarella <sgarzare@redhat.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>, 
	Jason Wang <jasowang@redhat.com>, Xuan Zhuo <xuanzhuo@linux.alibaba.com>, 
	Richard Weinberger <richard@nod.at>, Anton Ivanov <anton.ivanov@cambridgegreys.com>, 
	Johannes Berg <johannes@sipsolutions.net>, Paolo Bonzini <pbonzini@redhat.com>, 
	Stefan Hajnoczi <stefanha@redhat.com>, Jens Axboe <axboe@kernel.dk>, 
	Marcel Holtmann <marcel@holtmann.org>, Luiz Augusto von Dentz <luiz.dentz@gmail.com>, 
	Olivia Mackall <olivia@selenic.com>, Herbert Xu <herbert@gondor.apana.org.au>, 
	Amit Shah <amit@kernel.org>, Arnd Bergmann <arnd@arndb.de>, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Gonglei <arei.gonglei@huawei.com>, 
	"David S. Miller" <davem@davemloft.net>, Viresh Kumar <vireshk@kernel.org>, 
	Linus Walleij <linus.walleij@linaro.org>, Bartosz Golaszewski <brgl@bgdev.pl>, 
	David Airlie <airlied@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>, 
	Gurchetan Singh <gurchetansingh@chromium.org>, Chia-I Wu <olvaffe@gmail.com>, 
	Jean-Philippe Brucker <jean-philippe@linaro.org>, Joerg Roedel <joro@8bytes.org>, Alexander Graf <graf@amazon.com>, 
	Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, 
	Paolo Abeni <pabeni@redhat.com>, Eric Van Hensbergen <ericvh@kernel.org>, 
	Latchesar Ionkov <lucho@ionkov.net>, Dominique Martinet <asmadeus@codewreck.org>, 
	Christian Schoenebeck <linux_oss@crudebyte.com>, Kalle Valo <kvalo@kernel.org>, 
	Dan Williams <dan.j.williams@intel.com>, Vishal Verma <vishal.l.verma@intel.com>, 
	Dave Jiang <dave.jiang@intel.com>, Ira Weiny <ira.weiny@intel.com>, 
	Pankaj Gupta <pankaj.gupta.linux@gmail.com>, Bjorn Andersson <andersson@kernel.org>, 
	Mathieu Poirier <mathieu.poirier@linaro.org>, "Martin K. Petersen" <martin.petersen@oracle.com>, 
	Vivek Goyal <vgoyal@redhat.com>, Miklos Szeredi <miklos@szeredi.hu>, 
	Anton Yakovlev <anton.yakovlev@opensynergy.com>, Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>, 
	virtualization@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-um@lists.infradead.org, linux-block@vger.kernel.org, linux-bluetooth@vger.kernel.org, 
	linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org, 
	dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, netdev@vger.kernel.org, 
	v9fs@lists.linux.dev, kvm@vger.kernel.org, linux-wireless@vger.kernel.org, 
	nvdimm@lists.linux.dev, linux-remoteproc@vger.kernel.org, linux-scsi@vger.kernel.org, 
	linux-fsdevel@vger.kernel.org, alsa-devel@alsa-project.org, linux-sound@vger.kernel.org
Subject: Re: [PATCH 01/22] virtio: store owner from modules with
 register_virtio_driver()
Message-ID: <oaoiehcpkjs3wrhc22pwx676pompxml2z5dcq32a6fvsyntonw@hnohrbbp6wpm>
References: <20240327-module-owner-virtio-v1-0-0feffab77d99@linaro.org>
 <20240327-module-owner-virtio-v1-1-0feffab77d99@linaro.org>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Disposition: inline
In-Reply-To: <20240327-module-owner-virtio-v1-1-0feffab77d99@linaro.org>

On Wed, Mar 27, 2024 at 01:40:54PM +0100, Krzysztof Kozlowski wrote:
>Modules registering driver with register_virtio_driver() might forget to
>set .owner field.  i2c-virtio.c for example has it missing.  The field
>is used by some of other kernel parts for reference counting
>(try_module_get()), so it is expected that drivers will set it.
>
>Solve the problem by moving this task away from the drivers to the core
>amba bus code, just like we did for platform_driver in
>commit 9447057eaff8 ("platform_device: use a macro instead of
>platform_driver_register").
>
>Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>---
> Documentation/driver-api/virtio/writing_virtio_drivers.rst | 1 -
> drivers/virtio/virtio.c                                    | 6 ++++--
> include/linux/virtio.h                                     | 7 +++++--
> 3 files changed, 9 insertions(+), 5 deletions(-)
>
>diff --git a/Documentation/driver-api/virtio/writing_virtio_drivers.rst b/Documentation/driver-api/virtio/writing_virtio_drivers.rst
>index e14c58796d25..e5de6f5d061a 100644
>--- a/Documentation/driver-api/virtio/writing_virtio_drivers.rst
>+++ b/Documentation/driver-api/virtio/writing_virtio_drivers.rst
>@@ -97,7 +97,6 @@ like this::
>
> 	static struct virtio_driver virtio_dummy_driver = {
> 		.driver.name =  KBUILD_MODNAME,
>-		.driver.owner = THIS_MODULE,
> 		.id_table =     id_table,
> 		.probe =        virtio_dummy_probe,
> 		.remove =       virtio_dummy_remove,
>diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
>index f173587893cb..9510c551dce8 100644
>--- a/drivers/virtio/virtio.c
>+++ b/drivers/virtio/virtio.c
>@@ -362,14 +362,16 @@ static const struct bus_type virtio_bus = {
> 	.remove = virtio_dev_remove,
> };
>
>-int register_virtio_driver(struct virtio_driver *driver)
>+int __register_virtio_driver(struct virtio_driver *driver, struct module *owner)
> {
> 	/* Catch this early. */
> 	BUG_ON(driver->feature_table_size && !driver->feature_table);
> 	driver->driver.bus = &virtio_bus;
>+	driver->driver.owner = owner;
>+

`.driver.name =  KBUILD_MODNAME` also seems very common, should we put
that in the macro as well?

> 	return driver_register(&driver->driver);
> }
>-EXPORT_SYMBOL_GPL(register_virtio_driver);
>+EXPORT_SYMBOL_GPL(__register_virtio_driver);
>
> void unregister_virtio_driver(struct virtio_driver *driver)
> {
>diff --git a/include/linux/virtio.h b/include/linux/virtio.h
>index b0201747a263..26c4325aa373 100644
>--- a/include/linux/virtio.h
>+++ b/include/linux/virtio.h
>@@ -170,7 +170,7 @@ size_t virtio_max_dma_size(const struct virtio_device *vdev);
>
> /**
>  * struct virtio_driver - operations for a virtio I/O driver
>- * @driver: underlying device driver (populate name and owner).
>+ * @driver: underlying device driver (populate name).
>  * @id_table: the ids serviced by this driver.
>  * @feature_table: an array of feature numbers supported by this driver.
>  * @feature_table_size: number of entries in the feature table array.
>@@ -208,7 +208,10 @@ static inline struct virtio_driver *drv_to_virtio(struct device_driver *drv)
> 	return container_of(drv, struct virtio_driver, driver);
> }
>
>-int register_virtio_driver(struct virtio_driver *drv);
>+/* use a macro to avoid include chaining to get THIS_MODULE */
>+#define register_virtio_driver(drv) \
>+	__register_virtio_driver(drv, THIS_MODULE)
>+int __register_virtio_driver(struct virtio_driver *drv, struct module *owner);
> void unregister_virtio_driver(struct virtio_driver *drv);
>
> /* module_virtio_driver() - Helper macro for drivers that don't do
>
>-- 
>2.34.1
>