linux-kernel - Re: [RFC PATCH v1 03/22] PCI: change PCI device management code to better follow device model

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Date:	Tue, 11 Sep 2012 16:03:50 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Jiang Liu <liuj97@...il.com>
Cc:	Don Dutile <ddutile@...hat.com>, Yinghai Lu <yinghai@...nel.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Jiang Liu <jiang.liu@...wei.com>,
	Taku Izumi <izumi.taku@...fujitsu.com>,
	"Rafael J . Wysocki" <rjw@...k.pl>,
	Yijing Wang <wangyijing@...wei.com>,
	Xinwei Hu <huxinwei@...wei.com>, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org
Subject: Re: [RFC PATCH v1 03/22] PCI: change PCI device management code to
 better follow device model

On Tue, Aug 7, 2012 at 10:10 AM, Jiang Liu <liuj97@...il.com> wrote:
> According to device model documentation, the way to add/remove device
> object should be symmetric.
>
> /**
>  * device_del - delete device from system.
>  * @dev: device.
>  *
>  * This is the first part of the device unregistration
>  * sequence. This removes the device from the lists we control
>  * from here, has it removed from the other driver model
>  * subsystems it was added to in device_add(), and removes it
>  * from the kobject hierarchy.
>  *
>  * NOTE: this should be called manually _iff_ device_add() was
>  * also called manually.
>  */
>
> The rule here is to either use
> 1) device_register()/device_unregister()
> or
> 2) device_initialize()/device_add()/device_del()/put_device().
>
> So change PCI core to follow the rule and get rid of the redundant
> pci_dev_get()/pci_dev_put() pair.

Seems OK to me.

> Signed-off-by: Jiang Liu <liuj97@...il.com>
> ---
>  drivers/pci/probe.c  |    1 -
>  drivers/pci/remove.c |    4 ++--
>  2 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 0840409..dacca26 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1294,7 +1294,6 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
>  {
>         device_initialize(&dev->dev);
>         dev->dev.release = pci_release_dev;
> -       pci_dev_get(dev);
>
>         dev->dev.dma_mask = &dev->dma_mask;
>         dev->dev.dma_parms = &dev->dma_parms;
> diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
> index 33b6318..b9ac765 100644
> --- a/drivers/pci/remove.c
> +++ b/drivers/pci/remove.c
> @@ -22,7 +22,7 @@ static void pci_stop_dev(struct pci_dev *dev)
>         if (dev->is_added) {
>                 pci_proc_detach_device(dev);
>                 pci_remove_sysfs_dev_files(dev);
> -               device_unregister(&dev->dev);
> +               device_del(&dev->dev);
>                 dev->is_added = 0;
>         }
>
> @@ -40,7 +40,7 @@ static void pci_destroy_dev(struct pci_dev *dev)
>         up_write(&pci_bus_sem);
>
>         pci_free_resources(dev);
> -       pci_dev_put(dev);
> +       put_device(&dev->dev);
>  }
>
>  /**
> --
> 1.7.9.5
>
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