linux-kernel - Re: [PATCH] Create PNP device attributes via dev

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Date:	Tue, 23 Sep 2008 21:59:19 -0700
From:	"Kay Sievers" <kay.sievers@...y.org>
To:	"Drew Moseley" <dmoseley@...sta.com>
Cc:	ambx1@....rr.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Create PNP device attributes via dev_attrs field of struct device

On Tue, Sep 23, 2008 at 14:24, Drew Moseley <dmoseley@...sta.com> wrote:
> I have seen an issue where the sysfs entries for a PNP device are
> created nonatomically resulting in a race condition with freedesktop
> HAL.  The patch below is my first attempt at addressing this by creating
> the device attributes as default bus attributes and allowing the
> device_register() call to create them.  Any nasty side effects I am not
> addressing?  Comments?

> diff --git a/drivers/pnp/base.h b/drivers/pnp/base.h
> index 9fd7bb9..b07787f 100644
> --- a/drivers/pnp/base.h
> +++ b/drivers/pnp/base.h
> @@ -16,7 +16,7 @@ struct pnp_card *pnp_alloc_card(struct pnp_protocol *,
> int id, char *pnpid);
>
>  int pnp_add_device(struct pnp_dev *dev);
>  struct pnp_id *pnp_add_id(struct pnp_dev *dev, char *id);
> -int pnp_interface_attach_device(struct pnp_dev *dev);
> +void pnp_interface_attach_device(struct pnp_dev *dev);
>
>  int pnp_add_card(struct pnp_card *card);
>  void pnp_remove_card(struct pnp_card *card);
> diff --git a/drivers/pnp/core.c b/drivers/pnp/core.c
> index a411582..bcd49ba 100644
> --- a/drivers/pnp/core.c
> +++ b/drivers/pnp/core.c
> @@ -159,8 +159,6 @@ struct pnp_dev *pnp_alloc_dev(struct pnp_protocol
> *protocol, int id, char *pnpid
>
>  int __pnp_add_device(struct pnp_dev *dev)
>  {
> -       int ret;
> -
>        pnp_fixup_device(dev);
>        dev->status = PNP_READY;
>        spin_lock(&pnp_lock);
> @@ -168,12 +166,8 @@ int __pnp_add_device(struct pnp_dev *dev)
>        list_add_tail(&dev->protocol_list, &dev->protocol->devices);
>        spin_unlock(&pnp_lock);
>
> -       ret = device_register(&dev->dev);
> -       if (ret)
> -               return ret;
> -
>        pnp_interface_attach_device(dev);
> -       return 0;
> +       return device_register(&dev->dev);
>  }
>
>  /*
> diff --git a/drivers/pnp/interface.c b/drivers/pnp/interface.c
> index a876ecf..442684d 100644
> --- a/drivers/pnp/interface.c
> +++ b/drivers/pnp/interface.c
> @@ -243,8 +243,6 @@ static ssize_t pnp_show_options(struct device *dmdev,
>        return ret;
>  }
>
> -static DEVICE_ATTR(options, S_IRUGO, pnp_show_options, NULL);
> -
>  static ssize_t pnp_show_current_resources(struct device *dmdev,
>                                          struct device_attribute *attr,
>                                          char *buf)
> @@ -420,9 +418,6 @@ done:
>        return count;
>  }
>
> -static DEVICE_ATTR(resources, S_IRUGO | S_IWUSR,
> -                  pnp_show_current_resources, pnp_set_current_resources);
> -
>  static ssize_t pnp_show_current_ids(struct device *dmdev,
>                                    struct device_attribute *attr, char *buf)
>  {
> @@ -437,27 +432,16 @@ static ssize_t pnp_show_current_ids(struct device
> *dmdev,
>        return (str - buf);
>  }
>
> -static DEVICE_ATTR(id, S_IRUGO, pnp_show_current_ids, NULL);
> +static struct device_attribute pnp_interface_attrs[] = {
> +       __ATTR(resources, S_IRUGO | S_IWUSR,
> +                  pnp_show_current_resources,
> +                  pnp_set_current_resources),
> +       __ATTR(options, S_IRUGO, pnp_show_options, NULL),
> +       __ATTR(id, S_IRUGO, pnp_show_current_ids, NULL),
> +       __ATTR_NULL,
> +};
>
> -int pnp_interface_attach_device(struct pnp_dev *dev)
> +void pnp_interface_attach_device(struct pnp_dev *dev)
>  {
> -       int rc = device_create_file(&dev->dev, &dev_attr_options);
> -
> -       if (rc)
> -               goto err;
> -       rc = device_create_file(&dev->dev, &dev_attr_resources);
> -       if (rc)
> -               goto err_opt;
> -       rc = device_create_file(&dev->dev, &dev_attr_id);
> -       if (rc)
> -               goto err_res;
> -
> -       return 0;
> -
> -err_res:
> -       device_remove_file(&dev->dev, &dev_attr_resources);
> -err_opt:
> -       device_remove_file(&dev->dev, &dev_attr_options);
> -err:
> -       return rc;
> +       dev->dev.bus->dev_attrs = pnp_interface_attrs;

Any reason not to assign it statically to pnp_bus_type at in
drivers/pnp/driver.c?

>  }

Thanks,
Kay
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