Patchwork EEH: remove eeh device from OF node

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Submitter Gavin Shan
Date March 14, 2012, 10:31 a.m.
Message ID <1331721086-4314-1-git-send-email-shangw@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/146600/
State Rejected
Delegated to: Benjamin Herrenschmidt
Headers show

Comments

Gavin Shan - March 14, 2012, 10:31 a.m.
Originally, the PCI sensitive OF node is tracing the eeh device
through struct device_node::edev. However, it was regarded as
bad idea.

The patch removes struct device_node::edev. In addition, the
global list of eeh devices is introduced, and do retrival of
eeh device according to the given OF node through the global
list.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/eeh.h           |    7 +++++++
 arch/powerpc/platforms/pseries/eeh_dev.c |   29 ++++++++++++++++++++++++++++-
 include/linux/of.h                       |   10 ----------
 3 files changed, 35 insertions(+), 11 deletions(-)
Benjamin Herrenschmidt - March 21, 2012, 12:14 a.m.
On Wed, 2012-03-14 at 18:31 +0800, Gavin Shan wrote:
> Originally, the PCI sensitive OF node is tracing the eeh device
> through struct device_node::edev. However, it was regarded as
> bad idea.
> 
> The patch removes struct device_node::edev. In addition, the
> global list of eeh devices is introduced, and do retrival of
> eeh device according to the given OF node through the global
> list.

So I'm not too happy with that. The main problem I see is that
the code -constantly- calls of_node_to_eeh_dev.

IE. On any MMIO that happens to return all 1's, we'll call
eeh_check_failure() for example, which does that. In fact for a hot path
it's pretty horrid, it will:

 - Do an address cache lookup to get the pci_dev
 - Get the device-node frokm the pci_dev
 - Lookup your list to get the eeh_dev

Shouldn't we instead change the address cache to contain eeh_dev
instead ? And if you prefer keeping pci_dev, then it shouldn't be hard
to stick a pointer to the eeh_dev in there via either struct archdata or
maybe platform_data.

The EEH code still, even after your rework, constantly pass "dn"'s as
argument to functions just to convert it back to a struct eeh_dev rather
than trying to pass the eeh_dev.

So turning that into a list lookup will slow things down to a crawl.
Also your patch never seems to remove anything from your list, which
doesn't look right vs. hotplug.

I suggest we fix that with a two phase approach:

 1- ASAP so we can still get that into 3.4, move the eeh_dev pointer to
struct pci_dn instead of struct device_node. This structure is
accessible directly via dn->data and is ppc specific, that will be a
better temporary solution and and adding stuff to the generic struct
device_node.

 2- Then, what we need to do is generalize the use of eeh_dev rather
than device_node as the main object being worked on in the eeh layer and
thus as the argument to most functions.

Cheers,
Ben.

> Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/eeh.h           |    7 +++++++
>  arch/powerpc/platforms/pseries/eeh_dev.c |   29 ++++++++++++++++++++++++++++-
>  include/linux/of.h                       |   10 ----------
>  3 files changed, 35 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
> index d60f998..591e0a1 100644
> --- a/arch/powerpc/include/asm/eeh.h
> +++ b/arch/powerpc/include/asm/eeh.h
> @@ -56,6 +56,7 @@ struct eeh_dev {
>  	struct pci_controller *phb;	/* Associated PHB		*/
>  	struct device_node *dn;		/* Associated device node	*/
>  	struct pci_dev *pdev;		/* Associated PCI device	*/
> +	struct list_head list;		/* Form the global link list	*/
>  };
>  
>  static inline struct device_node *eeh_dev_to_of_node(struct eeh_dev *edev)
> @@ -115,6 +116,7 @@ extern int eeh_subsystem_enabled;
>   */
>  #define EEH_MAX_ALLOWED_FREEZES 5
>  
> +struct eeh_dev *eeh_dev_from_of_node(struct device_node *dn);
>  void * __devinit eeh_dev_init(struct device_node *dn, void *data);
>  void __devinit eeh_dev_phb_init_dynamic(struct pci_controller *phb);
>  void __init eeh_dev_phb_init(void);
> @@ -132,6 +134,11 @@ void eeh_add_device_tree_early(struct device_node *);
>  void eeh_add_device_tree_late(struct pci_bus *);
>  void eeh_remove_bus_device(struct pci_dev *);
>  
> +static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn)
> +{
> +	return eeh_dev_from_of_node(dn);
> +}
> +
>  /**
>   * EEH_POSSIBLE_ERROR() -- test for possible MMIO failure.
>   *
> diff --git a/arch/powerpc/platforms/pseries/eeh_dev.c b/arch/powerpc/platforms/pseries/eeh_dev.c
> index f3aed7d..925d3a3 100644
> --- a/arch/powerpc/platforms/pseries/eeh_dev.c
> +++ b/arch/powerpc/platforms/pseries/eeh_dev.c
> @@ -34,6 +34,7 @@
>  #include <linux/export.h>
>  #include <linux/gfp.h>
>  #include <linux/init.h>
> +#include <linux/list.h>
>  #include <linux/kernel.h>
>  #include <linux/pci.h>
>  #include <linux/string.h>
> @@ -41,6 +42,30 @@
>  #include <asm/pci-bridge.h>
>  #include <asm/ppc-pci.h>
>  
> +/* eeh device list */
> +static LIST_HEAD(eeh_dev_list);
> +
> +/**
> + * eeh_dev_from_of_node - Retrieve EEH device according to OF node
> + * @dn: OF node
> + *
> + * All existing eeh devices have been put into the global list.
> + * In addition, the eeh device is tracing the corresponding
> + * OF node. The function is used to retrieve the corresponding
> + * eeh device according to the given OF node.
> + */
> +struct eeh_dev *eeh_dev_from_of_node(struct device_node *dn)
> +{
> +	struct eeh_dev *edev = NULL;
> +
> +	list_for_each_entry(edev, &eeh_dev_list, list) {
> +		if (edev->dn && edev->dn == dn)
> +			return edev;
> +	}
> +
> +	return NULL;
> +}
> +
>  /**
>   * eeh_dev_init - Create EEH device according to OF node
>   * @dn: device node
> @@ -62,10 +87,12 @@ void * __devinit eeh_dev_init(struct device_node *dn, void *data)
>  	}
>  
>  	/* Associate EEH device with OF node */
> -	dn->edev  = edev;
>  	edev->dn  = dn;
>  	edev->phb = phb;
>  
> +	/* Add to global list */
> +	list_add_tail(&edev->list, &eeh_dev_list);
> +
>  	return NULL;
>  }
>  
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 3e710d8..a75a831 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -58,9 +58,6 @@ struct device_node {
>  	struct	kref kref;
>  	unsigned long _flags;
>  	void	*data;
> -#if defined(CONFIG_EEH)
> -	struct eeh_dev *edev;
> -#endif
>  #if defined(CONFIG_SPARC)
>  	char	*path_component_name;
>  	unsigned int unique_id;
> @@ -75,13 +72,6 @@ struct of_phandle_args {
>  	uint32_t args[MAX_PHANDLE_ARGS];
>  };
>  
> -#if defined(CONFIG_EEH)
> -static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn)
> -{
> -	return dn->edev;
> -}
> -#endif
> -
>  #if defined(CONFIG_SPARC) || !defined(CONFIG_OF)
>  /* Dummy ref counting routines - to be implemented later */
>  static inline struct device_node *of_node_get(struct device_node *node)
Gavin Shan - March 22, 2012, 3:28 a.m.
>> Originally, the PCI sensitive OF node is tracing the eeh device
>> through struct device_node::edev. However, it was regarded as
>> bad idea.
>> 
>> The patch removes struct device_node::edev. In addition, the
>> global list of eeh devices is introduced, and do retrival of
>> eeh device according to the given OF node through the global
>> list.
>
>So I'm not too happy with that. The main problem I see is that
>the code -constantly- calls of_node_to_eeh_dev.
>

Yes, it's somewhat expensive.

>IE. On any MMIO that happens to return all 1's, we'll call
>eeh_check_failure() for example, which does that. In fact for a hot path
>it's pretty horrid, it will:
>
> - Do an address cache lookup to get the pci_dev
> - Get the device-node frokm the pci_dev
> - Lookup your list to get the eeh_dev
>
>Shouldn't we instead change the address cache to contain eeh_dev
>instead ? And if you prefer keeping pci_dev, then it shouldn't be hard
>to stick a pointer to the eeh_dev in there via either struct archdata or
>maybe platform_data.
>
>The EEH code still, even after your rework, constantly pass "dn"'s as
>argument to functions just to convert it back to a struct eeh_dev rather
>than trying to pass the eeh_dev.
>

I'm working on explicit PE support and hopefully, I can send out
the code next week for review. The basic idea is to introuce
struct eeh_pe and attached eeh_dev to the corresponding PE. In turn,
eeh core will use PE as parameter instead of current eeh_dev ;-)

>So turning that into a list lookup will slow things down to a crawl.
>Also your patch never seems to remove anything from your list, which
>doesn't look right vs. hotplug.
>
>I suggest we fix that with a two phase approach:
>
> 1- ASAP so we can still get that into 3.4, move the eeh_dev pointer to
>struct pci_dn instead of struct device_node. This structure is
>accessible directly via dn->data and is ppc specific, that will be a
>better temporary solution and and adding stuff to the generic struct
>device_node.
>

I've sent patch again it and please take a look when you have time.

> 2- Then, what we need to do is generalize the use of eeh_dev rather
>than device_node as the main object being worked on in the eeh layer and
>thus as the argument to most functions.
>
>Cheers,
>Ben.
>

Thanks,
Gavin

>> Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
>> ---
>>  arch/powerpc/include/asm/eeh.h           |    7 +++++++
>>  arch/powerpc/platforms/pseries/eeh_dev.c |   29 ++++++++++++++++++++++++++++-
>>  include/linux/of.h                       |   10 ----------
>>  3 files changed, 35 insertions(+), 11 deletions(-)
>> 
>> diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
>> index d60f998..591e0a1 100644
>> --- a/arch/powerpc/include/asm/eeh.h
>> +++ b/arch/powerpc/include/asm/eeh.h
>> @@ -56,6 +56,7 @@ struct eeh_dev {
>>  	struct pci_controller *phb;	/* Associated PHB		*/
>>  	struct device_node *dn;		/* Associated device node	*/
>>  	struct pci_dev *pdev;		/* Associated PCI device	*/
>> +	struct list_head list;		/* Form the global link list	*/
>>  };
>>  
>>  static inline struct device_node *eeh_dev_to_of_node(struct eeh_dev *edev)
>> @@ -115,6 +116,7 @@ extern int eeh_subsystem_enabled;
>>   */
>>  #define EEH_MAX_ALLOWED_FREEZES 5
>>  
>> +struct eeh_dev *eeh_dev_from_of_node(struct device_node *dn);
>>  void * __devinit eeh_dev_init(struct device_node *dn, void *data);
>>  void __devinit eeh_dev_phb_init_dynamic(struct pci_controller *phb);
>>  void __init eeh_dev_phb_init(void);
>> @@ -132,6 +134,11 @@ void eeh_add_device_tree_early(struct device_node *);
>>  void eeh_add_device_tree_late(struct pci_bus *);
>>  void eeh_remove_bus_device(struct pci_dev *);
>>  
>> +static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn)
>> +{
>> +	return eeh_dev_from_of_node(dn);
>> +}
>> +
>>  /**
>>   * EEH_POSSIBLE_ERROR() -- test for possible MMIO failure.
>>   *
>> diff --git a/arch/powerpc/platforms/pseries/eeh_dev.c b/arch/powerpc/platforms/pseries/eeh_dev.c
>> index f3aed7d..925d3a3 100644
>> --- a/arch/powerpc/platforms/pseries/eeh_dev.c
>> +++ b/arch/powerpc/platforms/pseries/eeh_dev.c
>> @@ -34,6 +34,7 @@
>>  #include <linux/export.h>
>>  #include <linux/gfp.h>
>>  #include <linux/init.h>
>> +#include <linux/list.h>
>>  #include <linux/kernel.h>
>>  #include <linux/pci.h>
>>  #include <linux/string.h>
>> @@ -41,6 +42,30 @@
>>  #include <asm/pci-bridge.h>
>>  #include <asm/ppc-pci.h>
>>  
>> +/* eeh device list */
>> +static LIST_HEAD(eeh_dev_list);
>> +
>> +/**
>> + * eeh_dev_from_of_node - Retrieve EEH device according to OF node
>> + * @dn: OF node
>> + *
>> + * All existing eeh devices have been put into the global list.
>> + * In addition, the eeh device is tracing the corresponding
>> + * OF node. The function is used to retrieve the corresponding
>> + * eeh device according to the given OF node.
>> + */
>> +struct eeh_dev *eeh_dev_from_of_node(struct device_node *dn)
>> +{
>> +	struct eeh_dev *edev = NULL;
>> +
>> +	list_for_each_entry(edev, &eeh_dev_list, list) {
>> +		if (edev->dn && edev->dn == dn)
>> +			return edev;
>> +	}
>> +
>> +	return NULL;
>> +}
>> +
>>  /**
>>   * eeh_dev_init - Create EEH device according to OF node
>>   * @dn: device node
>> @@ -62,10 +87,12 @@ void * __devinit eeh_dev_init(struct device_node *dn, void *data)
>>  	}
>>  
>>  	/* Associate EEH device with OF node */
>> -	dn->edev  = edev;
>>  	edev->dn  = dn;
>>  	edev->phb = phb;
>>  
>> +	/* Add to global list */
>> +	list_add_tail(&edev->list, &eeh_dev_list);
>> +
>>  	return NULL;
>>  }
>>  
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 3e710d8..a75a831 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -58,9 +58,6 @@ struct device_node {
>>  	struct	kref kref;
>>  	unsigned long _flags;
>>  	void	*data;
>> -#if defined(CONFIG_EEH)
>> -	struct eeh_dev *edev;
>> -#endif
>>  #if defined(CONFIG_SPARC)
>>  	char	*path_component_name;
>>  	unsigned int unique_id;
>> @@ -75,13 +72,6 @@ struct of_phandle_args {
>>  	uint32_t args[MAX_PHANDLE_ARGS];
>>  };
>>  
>> -#if defined(CONFIG_EEH)
>> -static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn)
>> -{
>> -	return dn->edev;
>> -}
>> -#endif
>> -
>>  #if defined(CONFIG_SPARC) || !defined(CONFIG_OF)
>>  /* Dummy ref counting routines - to be implemented later */
>>  static inline struct device_node *of_node_get(struct device_node *node)
>
>
Benjamin Herrenschmidt - March 22, 2012, 5:35 a.m.
On Thu, 2012-03-22 at 11:28 +0800, Gavin Shan wrote:

> > 1- ASAP so we can still get that into 3.4, move the eeh_dev pointer to
> >struct pci_dn instead of struct device_node. This structure is
> >accessible directly via dn->data and is ppc specific, that will be a
> >better temporary solution and and adding stuff to the generic struct
> >device_node.
> >
> 
> I've sent patch again it and please take a look when you have time.

All I see is your patch that does the lookup, I missed the patch to move
it to pci_dn, can you re-send that to me directly ?

Thanks !

Cheers,
Ben.

> > 2- Then, what we need to do is generalize the use of eeh_dev rather
> >than device_node as the main object being worked on in the eeh layer and
> >thus as the argument to most functions.
> >
> >Cheers,
> >Ben.
> >
> 
> Thanks,
> Gavin
> 
> >> Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
> >> ---
> >>  arch/powerpc/include/asm/eeh.h           |    7 +++++++
> >>  arch/powerpc/platforms/pseries/eeh_dev.c |   29 ++++++++++++++++++++++++++++-
> >>  include/linux/of.h                       |   10 ----------
> >>  3 files changed, 35 insertions(+), 11 deletions(-)
> >> 
> >> diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
> >> index d60f998..591e0a1 100644
> >> --- a/arch/powerpc/include/asm/eeh.h
> >> +++ b/arch/powerpc/include/asm/eeh.h
> >> @@ -56,6 +56,7 @@ struct eeh_dev {
> >>  	struct pci_controller *phb;	/* Associated PHB		*/
> >>  	struct device_node *dn;		/* Associated device node	*/
> >>  	struct pci_dev *pdev;		/* Associated PCI device	*/
> >> +	struct list_head list;		/* Form the global link list	*/
> >>  };
> >>  
> >>  static inline struct device_node *eeh_dev_to_of_node(struct eeh_dev *edev)
> >> @@ -115,6 +116,7 @@ extern int eeh_subsystem_enabled;
> >>   */
> >>  #define EEH_MAX_ALLOWED_FREEZES 5
> >>  
> >> +struct eeh_dev *eeh_dev_from_of_node(struct device_node *dn);
> >>  void * __devinit eeh_dev_init(struct device_node *dn, void *data);
> >>  void __devinit eeh_dev_phb_init_dynamic(struct pci_controller *phb);
> >>  void __init eeh_dev_phb_init(void);
> >> @@ -132,6 +134,11 @@ void eeh_add_device_tree_early(struct device_node *);
> >>  void eeh_add_device_tree_late(struct pci_bus *);
> >>  void eeh_remove_bus_device(struct pci_dev *);
> >>  
> >> +static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn)
> >> +{
> >> +	return eeh_dev_from_of_node(dn);
> >> +}
> >> +
> >>  /**
> >>   * EEH_POSSIBLE_ERROR() -- test for possible MMIO failure.
> >>   *
> >> diff --git a/arch/powerpc/platforms/pseries/eeh_dev.c b/arch/powerpc/platforms/pseries/eeh_dev.c
> >> index f3aed7d..925d3a3 100644
> >> --- a/arch/powerpc/platforms/pseries/eeh_dev.c
> >> +++ b/arch/powerpc/platforms/pseries/eeh_dev.c
> >> @@ -34,6 +34,7 @@
> >>  #include <linux/export.h>
> >>  #include <linux/gfp.h>
> >>  #include <linux/init.h>
> >> +#include <linux/list.h>
> >>  #include <linux/kernel.h>
> >>  #include <linux/pci.h>
> >>  #include <linux/string.h>
> >> @@ -41,6 +42,30 @@
> >>  #include <asm/pci-bridge.h>
> >>  #include <asm/ppc-pci.h>
> >>  
> >> +/* eeh device list */
> >> +static LIST_HEAD(eeh_dev_list);
> >> +
> >> +/**
> >> + * eeh_dev_from_of_node - Retrieve EEH device according to OF node
> >> + * @dn: OF node
> >> + *
> >> + * All existing eeh devices have been put into the global list.
> >> + * In addition, the eeh device is tracing the corresponding
> >> + * OF node. The function is used to retrieve the corresponding
> >> + * eeh device according to the given OF node.
> >> + */
> >> +struct eeh_dev *eeh_dev_from_of_node(struct device_node *dn)
> >> +{
> >> +	struct eeh_dev *edev = NULL;
> >> +
> >> +	list_for_each_entry(edev, &eeh_dev_list, list) {
> >> +		if (edev->dn && edev->dn == dn)
> >> +			return edev;
> >> +	}
> >> +
> >> +	return NULL;
> >> +}
> >> +
> >>  /**
> >>   * eeh_dev_init - Create EEH device according to OF node
> >>   * @dn: device node
> >> @@ -62,10 +87,12 @@ void * __devinit eeh_dev_init(struct device_node *dn, void *data)
> >>  	}
> >>  
> >>  	/* Associate EEH device with OF node */
> >> -	dn->edev  = edev;
> >>  	edev->dn  = dn;
> >>  	edev->phb = phb;
> >>  
> >> +	/* Add to global list */
> >> +	list_add_tail(&edev->list, &eeh_dev_list);
> >> +
> >>  	return NULL;
> >>  }
> >>  
> >> diff --git a/include/linux/of.h b/include/linux/of.h
> >> index 3e710d8..a75a831 100644
> >> --- a/include/linux/of.h
> >> +++ b/include/linux/of.h
> >> @@ -58,9 +58,6 @@ struct device_node {
> >>  	struct	kref kref;
> >>  	unsigned long _flags;
> >>  	void	*data;
> >> -#if defined(CONFIG_EEH)
> >> -	struct eeh_dev *edev;
> >> -#endif
> >>  #if defined(CONFIG_SPARC)
> >>  	char	*path_component_name;
> >>  	unsigned int unique_id;
> >> @@ -75,13 +72,6 @@ struct of_phandle_args {
> >>  	uint32_t args[MAX_PHANDLE_ARGS];
> >>  };
> >>  
> >> -#if defined(CONFIG_EEH)
> >> -static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn)
> >> -{
> >> -	return dn->edev;
> >> -}
> >> -#endif
> >> -
> >>  #if defined(CONFIG_SPARC) || !defined(CONFIG_OF)
> >>  /* Dummy ref counting routines - to be implemented later */
> >>  static inline struct device_node *of_node_get(struct device_node *node)
> >
> >

Patch

diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
index d60f998..591e0a1 100644
--- a/arch/powerpc/include/asm/eeh.h
+++ b/arch/powerpc/include/asm/eeh.h
@@ -56,6 +56,7 @@  struct eeh_dev {
 	struct pci_controller *phb;	/* Associated PHB		*/
 	struct device_node *dn;		/* Associated device node	*/
 	struct pci_dev *pdev;		/* Associated PCI device	*/
+	struct list_head list;		/* Form the global link list	*/
 };
 
 static inline struct device_node *eeh_dev_to_of_node(struct eeh_dev *edev)
@@ -115,6 +116,7 @@  extern int eeh_subsystem_enabled;
  */
 #define EEH_MAX_ALLOWED_FREEZES 5
 
+struct eeh_dev *eeh_dev_from_of_node(struct device_node *dn);
 void * __devinit eeh_dev_init(struct device_node *dn, void *data);
 void __devinit eeh_dev_phb_init_dynamic(struct pci_controller *phb);
 void __init eeh_dev_phb_init(void);
@@ -132,6 +134,11 @@  void eeh_add_device_tree_early(struct device_node *);
 void eeh_add_device_tree_late(struct pci_bus *);
 void eeh_remove_bus_device(struct pci_dev *);
 
+static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn)
+{
+	return eeh_dev_from_of_node(dn);
+}
+
 /**
  * EEH_POSSIBLE_ERROR() -- test for possible MMIO failure.
  *
diff --git a/arch/powerpc/platforms/pseries/eeh_dev.c b/arch/powerpc/platforms/pseries/eeh_dev.c
index f3aed7d..925d3a3 100644
--- a/arch/powerpc/platforms/pseries/eeh_dev.c
+++ b/arch/powerpc/platforms/pseries/eeh_dev.c
@@ -34,6 +34,7 @@ 
 #include <linux/export.h>
 #include <linux/gfp.h>
 #include <linux/init.h>
+#include <linux/list.h>
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/string.h>
@@ -41,6 +42,30 @@ 
 #include <asm/pci-bridge.h>
 #include <asm/ppc-pci.h>
 
+/* eeh device list */
+static LIST_HEAD(eeh_dev_list);
+
+/**
+ * eeh_dev_from_of_node - Retrieve EEH device according to OF node
+ * @dn: OF node
+ *
+ * All existing eeh devices have been put into the global list.
+ * In addition, the eeh device is tracing the corresponding
+ * OF node. The function is used to retrieve the corresponding
+ * eeh device according to the given OF node.
+ */
+struct eeh_dev *eeh_dev_from_of_node(struct device_node *dn)
+{
+	struct eeh_dev *edev = NULL;
+
+	list_for_each_entry(edev, &eeh_dev_list, list) {
+		if (edev->dn && edev->dn == dn)
+			return edev;
+	}
+
+	return NULL;
+}
+
 /**
  * eeh_dev_init - Create EEH device according to OF node
  * @dn: device node
@@ -62,10 +87,12 @@  void * __devinit eeh_dev_init(struct device_node *dn, void *data)
 	}
 
 	/* Associate EEH device with OF node */
-	dn->edev  = edev;
 	edev->dn  = dn;
 	edev->phb = phb;
 
+	/* Add to global list */
+	list_add_tail(&edev->list, &eeh_dev_list);
+
 	return NULL;
 }
 
diff --git a/include/linux/of.h b/include/linux/of.h
index 3e710d8..a75a831 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -58,9 +58,6 @@  struct device_node {
 	struct	kref kref;
 	unsigned long _flags;
 	void	*data;
-#if defined(CONFIG_EEH)
-	struct eeh_dev *edev;
-#endif
 #if defined(CONFIG_SPARC)
 	char	*path_component_name;
 	unsigned int unique_id;
@@ -75,13 +72,6 @@  struct of_phandle_args {
 	uint32_t args[MAX_PHANDLE_ARGS];
 };
 
-#if defined(CONFIG_EEH)
-static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn)
-{
-	return dn->edev;
-}
-#endif
-
 #if defined(CONFIG_SPARC) || !defined(CONFIG_OF)
 /* Dummy ref counting routines - to be implemented later */
 static inline struct device_node *of_node_get(struct device_node *node)