linux-kernel - Re: [PATCH] ACPI: Do not fail acpi_bind_one() if device is already bound correctly

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Date:	Fri, 2 Aug 2013 10:48:49 +0800
From:	Lan Tianyu <lantianyu1986@...il.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Toshi Kani <toshi.kani@...com>
Subject: Re: [PATCH] ACPI: Do not fail acpi_bind_one() if device is already
 bound correctly

2013/8/2 Rafael J. Wysocki <rjw@...k.pl>:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> Modify acpi_bind_one() so that it doesn't fail if the device
> represented by its first argument has already been bound to the
> given ACPI handle (second argument), because that is not a good
> enough reason for returning an error code.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/acpi/glue.c |   15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> Index: linux-pm/drivers/acpi/glue.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/glue.c
> +++ linux-pm/drivers/acpi/glue.c
> @@ -143,7 +143,10 @@ int acpi_bind_one(struct device *dev, ac
>         list_for_each_entry(pn, &acpi_dev->physical_node_list, node)
>                 if (pn->dev == dev) {
>                         dev_warn(dev, "Already associated with ACPI node\n");
> -                       goto err_free;
> +                       if (ACPI_HANDLE(dev) == handle)
> +                               retval = 0;
> +
> +                       goto out_free;
>                 }
>
>         /* allocate physical node id according to physical_node_id_bitmap */
> @@ -152,7 +155,7 @@ int acpi_bind_one(struct device *dev, ac
>                 ACPI_MAX_PHYSICAL_NODE);
>         if (physical_node->node_id >= ACPI_MAX_PHYSICAL_NODE) {
>                 retval = -ENOSPC;
> -               goto err_free;
> +               goto out_free;
>         }
>
>         set_bit(physical_node->node_id, acpi_dev->physical_node_id_bitmap);
> @@ -185,10 +188,14 @@ int acpi_bind_one(struct device *dev, ac
>         put_device(dev);
>         return retval;
>
> - err_free:
> + out_free:
>         mutex_unlock(&acpi_dev->physical_node_lock);
>         kfree(physical_node);
> -       goto err;
> +       if (retval)
> +               goto err;
> +
> +       put_device(dev);
> +       return 0;
>  }
>  EXPORT_SYMBOL_GPL(acpi_bind_one);

Hi Rafael:
            How about the following change?

diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index f70cc45..35f375e 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -183,19 +183,15 @@ int acpi_bind_one(struct device *dev, acpi_handle handle)

        return 0;

- err:
-       ACPI_HANDLE_SET(dev, NULL);
-       put_device(dev);
-       return retval;
-
  out_free:
        mutex_unlock(&acpi_dev->physical_node_lock);
        kfree(physical_node);
-       if (retval)
-               goto err;

+ err:
+       if (retval)
+               ACPI_HANDLE_SET(dev, NULL);
        put_device(dev);
-       return 0;
+       return retval;
 }
 EXPORT_SYMBOL_GPL(acpi_bind_one);
---------------

When I reviewed this patch, found the dev's acpi handle always
is set  to NULL if there is error. This seems make no sense for
the case that the handle has been set to dev before binding.

For this case, the acpi handle has been found before binding.
Actually, the device driver could control any resources under ACPI
node even if the binding failed. So adding one flag to differentiate
it.

diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index 35f375e..c868e51 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -113,6 +113,7 @@ int acpi_bind_one(struct device *dev, acpi_handle handle)
        acpi_status status;
        struct acpi_device_physical_node *physical_node, *pn;
        char physical_node_name[sizeof(PHYSICAL_NODE_STRING) + 2];
+       bool has_handle = false;
        int retval = -EINVAL;

        if (ACPI_HANDLE(dev)) {
@@ -121,6 +122,7 @@ int acpi_bind_one(struct device *dev, acpi_handle handle)
                        return -EINVAL;
                } else {
                        handle = ACPI_HANDLE(dev);
+                       has_handle = true;
                }
        }
        if (!handle)
@@ -188,7 +190,7 @@ int acpi_bind_one(struct device *dev, acpi_handle handle)
        kfree(physical_node);

  err:
-       if (retval)
+       if (retval && !has_handle)
                ACPI_HANDLE_SET(dev, NULL);
        put_device(dev);
        return retval;



>
>
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-- 
Best regards
Tianyu Lan
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