From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D896C17582 for ; Wed, 7 Feb 2024 10:46:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707302775; cv=none; b=lqHoFY4yXKdqQjULur5PzNnRPwIhhcN+SFGMFo6Q/6XmRPP968HaiG2I5vcsGCTT9DE7bSMuDmwZdT7FCqeGi//JH0VT3Bb/4MqvxJxTVlC2xXHe/Z+YzfVjOwXOjLKyTug53oAD2hbi0ThvmRDENQekq+40CiSEHFmsIszspYE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707302775; c=relaxed/simple; bh=JUC5pmGAzWpqEgyes88EhCXyc6dXiIiiwfdTYwc/+NE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tDotPEfwUgHfrYex5joD3jp7oJ1TlH1N2nH+dY+oEa9nky/RnudfjVDEsggasIgflVUpmGqt6uGHLvvfDalnzoFgZKlsldAzmEgOWyuRa+MHHotH3lp3+eI8MFx4JCvl2Dar6S3WDuF5PpwosjNAMZtwnqzUL1DCKJeaNhiYOdw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=Y07aEhHk; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="Y07aEhHk" Received: from pendragon.ideasonboard.com (117.145-247-81.adsl-dyn.isp.belgacom.be [81.247.145.117]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 7BBAE975; Wed, 7 Feb 2024 11:44:47 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1707302687; bh=JUC5pmGAzWpqEgyes88EhCXyc6dXiIiiwfdTYwc/+NE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Y07aEhHkRNupHXv8qaXZmy6H5wsGt8nzSobyeAnaFyS48ISMN9yBKNQ3Njk9ILyPg PAVRr+pIQY4TwKB/79HcByz9n9nnmPxoO+PDamfZ4/fkYL87Rf9WTMNxO3TuPaU2Mz GdqmF15qyt+zcj7IJxsrKTCtFrxJgNR12yvZITxo= Date: Wed, 7 Feb 2024 12:46:13 +0200 From: Laurent Pinchart To: Sakari Ailus Cc: linux-media@vger.kernel.org, Hans Verkuil Subject: Re: [PATCH v2 11/29] media: mc: Split initialising and adding media devnode Message-ID: <20240207104613.GH23702@pendragon.ideasonboard.com> References: <20231220103713.113386-1-sakari.ailus@linux.intel.com> <20231220103713.113386-12-sakari.ailus@linux.intel.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20231220103713.113386-12-sakari.ailus@linux.intel.com> Hi Sakari, Thank you for the patch. On Wed, Dec 20, 2023 at 12:36:55PM +0200, Sakari Ailus wrote: > As registering a device node of an entity belonging to a media device Did you mean s/As registering/Registering/ ? > will require a reference to the struct device. Taking that reference is > only possible once the device has been initialised, which took place only s/took/takes/ > when it was registered. Split this in two, and initialise the device when s/was/is/ > the media device is allocated. > > Don't distribute the effects of these changes yet. Add media_device_get() > and media_device_put() first. Don't propagate the effects of these changes to drivers yet, we want to expose media_device refcounting with media_device_get() and media_device_put() functions first. I'm not sure that's exactly what you meant though. > Signed-off-by: Sakari Ailus > Acked-by: Hans Verkuil Reviewed-by: Laurent Pinchart > --- > drivers/media/mc/mc-device.c | 18 +++++++++++++----- > drivers/media/mc/mc-devnode.c | 17 ++++++++++------- > include/media/media-devnode.h | 19 ++++++++++++++----- > 3 files changed, 37 insertions(+), 17 deletions(-) > > diff --git a/drivers/media/mc/mc-device.c b/drivers/media/mc/mc-device.c > index c0ea08a8fc31..ebf037cd5f4a 100644 > --- a/drivers/media/mc/mc-device.c > +++ b/drivers/media/mc/mc-device.c > @@ -717,19 +717,26 @@ int __must_check __media_device_register(struct media_device *mdev, > /* Set version 0 to indicate user-space that the graph is static */ > mdev->topology_version = 0; > > + media_devnode_init(&mdev->devnode); > + > ret = media_devnode_register(&mdev->devnode, owner); > if (ret < 0) > - return ret; > + goto out_put; > > ret = device_create_file(&mdev->devnode.dev, &dev_attr_model); > - if (ret < 0) { > - media_devnode_unregister(&mdev->devnode); > - return ret; > - } > + if (ret < 0) > + goto out_unregister; > > dev_dbg(mdev->dev, "Media device registered\n"); > > return 0; > + > +out_unregister: I would name the labels err_unregister and err_put. > + media_devnode_unregister(&mdev->devnode); > +out_put: > + put_device(&mdev->devnode.dev); > + > + return ret; > } > EXPORT_SYMBOL_GPL(__media_device_register); > > @@ -803,6 +810,7 @@ void media_device_unregister(struct media_device *mdev) > device_remove_file(&mdev->devnode.dev, &dev_attr_model); > dev_dbg(mdev->dev, "Media device unregistering\n"); > media_devnode_unregister(&mdev->devnode); > + put_device(&mdev->devnode.dev); > } > EXPORT_SYMBOL_GPL(media_device_unregister); > > diff --git a/drivers/media/mc/mc-devnode.c b/drivers/media/mc/mc-devnode.c > index 8bc7450ac144..7b17419050fb 100644 > --- a/drivers/media/mc/mc-devnode.c > +++ b/drivers/media/mc/mc-devnode.c > @@ -204,6 +204,11 @@ static const struct file_operations media_devnode_fops = { > .llseek = no_llseek, > }; > > +void media_devnode_init(struct media_devnode *devnode) > +{ > + device_initialize(&devnode->dev); > +} > + > int __must_check media_devnode_register(struct media_devnode *devnode, > struct module *owner) > { > @@ -235,7 +240,6 @@ int __must_check media_devnode_register(struct media_devnode *devnode, > if (devnode->parent) > devnode->dev.parent = devnode->parent; > dev_set_name(&devnode->dev, "media%d", devnode->minor); > - device_initialize(&devnode->dev); > > /* Part 3: Add the media and character devices */ > ret = cdev_device_add(&devnode->cdev, &devnode->dev); > @@ -267,14 +271,13 @@ void media_devnode_unregister(struct media_devnode *devnode) > clear_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); > mutex_unlock(&media_devnode_lock); > > - cdev_del(&devnode->cdev); > - device_unregister(&devnode->dev); > + cdev_device_del(&devnode->cdev, &devnode->dev); > } > > /* > * Initialise media for linux > */ > -static int __init media_devnode_init(void) > +static int __init media_devnode_module_init(void) > { > int ret; > > @@ -296,14 +299,14 @@ static int __init media_devnode_init(void) > return 0; > } > > -static void __exit media_devnode_exit(void) > +static void __exit media_devnode_module_exit(void) > { > bus_unregister(&media_bus_type); > unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES); > } > > -subsys_initcall(media_devnode_init); > -module_exit(media_devnode_exit) > +subsys_initcall(media_devnode_module_init); > +module_exit(media_devnode_module_exit) > > MODULE_AUTHOR("Laurent Pinchart "); > MODULE_DESCRIPTION("Device node registration for media drivers"); > diff --git a/include/media/media-devnode.h b/include/media/media-devnode.h > index 1117d1dfd6bf..6d46c658be21 100644 > --- a/include/media/media-devnode.h > +++ b/include/media/media-devnode.h > @@ -90,6 +90,17 @@ struct media_devnode { > /* dev to media_devnode */ > #define to_media_devnode(cd) container_of(cd, struct media_devnode, dev) > > +/** > + * media_devnode_init - initialise a media devnode > + * > + * @devnode: struct media_devnode we want to initialise > + * > + * Initialise a media devnode. Note that after initialising the media > + * devnode is refcounted. Releasing references to it may be done using > + * put_device(). > + */ > +void media_devnode_init(struct media_devnode *devnode); > + > /** > * media_devnode_register - register a media device node > * > @@ -100,11 +111,9 @@ struct media_devnode { > * with the kernel. An error is returned if no free minor number can be found, > * or if the registration of the device node fails. > * > - * Zero is returned on success. > - * > - * Note that if the media_devnode_register call fails, the release() callback of > - * the media_devnode structure is *not* called, so the caller is responsible for > - * freeing any data. > + * Zero is returned on success. Note that in case > + * media_devnode_register() fails, the caller is responsible for > + * releasing the reference to the device using put_device(). > */ > int __must_check media_devnode_register(struct media_devnode *devnode, > struct module *owner); -- Regards, Laurent Pinchart