[v2,08/24] EDAC: Introduce mci_for_each_dimm() iterator

Message ID 20190624150758.6695-9-rrichter@marvell.com
State New
Headers show
Series
  • EDAC, mc, ghes: Fixes and updates to improve memory error reporting
Related show

Commit Message

Robert Richter June 24, 2019, 3:09 p.m.
Make code more readable by introducing a mci_for_each_dimm() iterator.
Now, we just get a pointer to a struct dimm_info. Direct array access
using an index is no longer needed to iterate.

Signed-off-by: Robert Richter <rrichter@marvell.com>

---
 drivers/edac/edac_mc.c       | 18 ++++++++++--------
 drivers/edac/edac_mc_sysfs.c | 34 +++++++++++++++-------------------
 drivers/edac/ghes_edac.c     |  8 ++++----
 drivers/edac/i5100_edac.c    | 11 +++++------
 include/linux/edac.h         |  7 +++++++
 5 files changed, 41 insertions(+), 37 deletions(-)

-- 
2.20.1

Comments

Borislav Petkov Aug. 14, 2019, 3:18 p.m. | #1
On Mon, Jun 24, 2019 at 03:09:11PM +0000, Robert Richter wrote:
> Make code more readable by introducing a mci_for_each_dimm() iterator.

> Now, we just get a pointer to a struct dimm_info. Direct array access

> using an index is no longer needed to iterate.

> 

> Signed-off-by: Robert Richter <rrichter@marvell.com>

> ---

>  drivers/edac/edac_mc.c       | 18 ++++++++++--------

>  drivers/edac/edac_mc_sysfs.c | 34 +++++++++++++++-------------------

>  drivers/edac/ghes_edac.c     |  8 ++++----

>  drivers/edac/i5100_edac.c    | 11 +++++------

>  include/linux/edac.h         |  7 +++++++

>  5 files changed, 41 insertions(+), 37 deletions(-)

> 

> diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c

> index c44bc83e8502..27277ca46ab3 100644

> --- a/drivers/edac/edac_mc.c

> +++ b/drivers/edac/edac_mc.c

> @@ -145,15 +145,18 @@ static void edac_mc_dump_channel(struct rank_info *chan)

>  	edac_dbg(4, "    channel->dimm = %p\n", chan->dimm);

>  }

>  

> -static void edac_mc_dump_dimm(struct dimm_info *dimm, int number)

> +static void edac_mc_dump_dimm(struct dimm_info *dimm)

>  {

>  	char location[80];

>  

> +	if (!dimm->nr_pages)

> +		return;

> +


What's that for?

>  	edac_dimm_info_location(dimm, location, sizeof(location));

>  

>  	edac_dbg(4, "%s%i: %smapped as virtual row %d, chan %d\n",

>  		 dimm->mci->csbased ? "rank" : "dimm",

> -		 number, location, dimm->csrow, dimm->cschannel);

> +		 dimm->idx, location, dimm->csrow, dimm->cschannel);

>  	edac_dbg(4, "  dimm = %p\n", dimm);

>  	edac_dbg(4, "  dimm->label = '%s'\n", dimm->label);

>  	edac_dbg(4, "  dimm->nr_pages = 0x%x\n", dimm->nr_pages);

> @@ -703,6 +706,7 @@ EXPORT_SYMBOL_GPL(edac_get_owner);

>  int edac_mc_add_mc_with_groups(struct mem_ctl_info *mci,

>  			       const struct attribute_group **groups)

>  {

> +	struct dimm_info *dimm;

>  	int ret = -EINVAL;

>  	edac_dbg(0, "\n");

>  

> @@ -727,9 +731,8 @@ int edac_mc_add_mc_with_groups(struct mem_ctl_info *mci,

>  				if (csrow->channels[j]->dimm->nr_pages)

>  					edac_mc_dump_channel(csrow->channels[j]);

>  		}

> -		for (i = 0; i < mci->tot_dimms; i++)

> -			if (mci->dimms[i]->nr_pages)

> -				edac_mc_dump_dimm(mci->dimms[i], i);


<---- newline here.

> +		mci_for_each_dimm(mci, dimm)

> +			edac_mc_dump_dimm(dimm);

>  	}

>  #endif

>  	mutex_lock(&mem_ctls_mutex);


...

> @@ -950,9 +949,10 @@ int edac_create_sysfs_mci_device(struct mem_ctl_info *mci,

>  			printk(KERN_CONT "\n");

>  		}

>  #endif

> -		err = edac_create_dimm_object(mci, dimm, i);

> +		err = edac_create_dimm_object(mci, dimm);

>  		if (err) {

> -			edac_dbg(1, "failure: create dimm %d obj\n", i);

> +			edac_dbg(1, "failure: create dimm %d obj\n",

> +				dimm->idx);

>  			goto fail_unregister_dimm;

>  		}

>  	}


Since you're touching this, pls do

s/dimm/DIMM/g

in the user-visible strings because it is an abbreviation.

> @@ -967,12 +967,9 @@ int edac_create_sysfs_mci_device(struct mem_ctl_info *mci,

>  	return 0;

>  

>  fail_unregister_dimm:

> -	for (i--; i >= 0; i--) {

> -		struct dimm_info *dimm = mci->dimms[i];

> -		if (!dimm->nr_pages)

> -			continue;

> -

> -		device_unregister(&dimm->dev);

> +	mci_for_each_dimm(mci, dimm) {

> +		if (device_is_registered(&dimm->dev))

> +			device_unregister(&dimm->dev);

>  	}

>  	device_unregister(&mci->dev);

>  

> @@ -984,7 +981,7 @@ int edac_create_sysfs_mci_device(struct mem_ctl_info *mci,

>   */

>  void edac_remove_sysfs_mci_device(struct mem_ctl_info *mci)

>  {

> -	int i;

> +	struct dimm_info *dimm;

>  

>  	edac_dbg(0, "\n");

>  

> @@ -995,8 +992,7 @@ void edac_remove_sysfs_mci_device(struct mem_ctl_info *mci)

>  	edac_delete_csrow_objects(mci);

>  #endif

>  

> -	for (i = 0; i < mci->tot_dimms; i++) {

> -		struct dimm_info *dimm = mci->dimms[i];

> +	mci_for_each_dimm(mci, dimm) {

>  		if (dimm->nr_pages == 0)

>  			continue;

>  		edac_dbg(0, "removing device %s\n", dev_name(&dimm->dev));

> diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c

> index 8050f9577fe6..72e75ea5526c 100644

> --- a/drivers/edac/ghes_edac.c

> +++ b/drivers/edac/ghes_edac.c

> @@ -81,11 +81,11 @@ static void ghes_edac_count_dimms(const struct dmi_header *dh, void *arg)

>  static int get_dimm_smbios_index(u16 handle)

>  {

>  	struct mem_ctl_info *mci = ghes_pvt->mci;

> -	int i;

> +	struct dimm_info *dimm;

>  

> -	for (i = 0; i < mci->tot_dimms; i++) {

> -		if (mci->dimms[i]->smbios_handle == handle)

> -			return i;

> +	mci_for_each_dimm(mci, dimm) {

> +		if (dimm->smbios_handle == handle)

> +			return dimm->idx;

>  	}

>  	return -1;

>  }

> diff --git a/drivers/edac/i5100_edac.c b/drivers/edac/i5100_edac.c

> index 39ba7f2414ae..7ec42b26a716 100644

> --- a/drivers/edac/i5100_edac.c

> +++ b/drivers/edac/i5100_edac.c

> @@ -846,14 +846,13 @@ static void i5100_init_interleaving(struct pci_dev *pdev,

>  

>  static void i5100_init_csrows(struct mem_ctl_info *mci)

>  {

> -	int i;

>  	struct i5100_priv *priv = mci->pvt_info;

> +	struct dimm_info *dimm;

>  

> -	for (i = 0; i < mci->tot_dimms; i++) {

> -		struct dimm_info *dimm;

> -		const unsigned long npages = i5100_npages(mci, i);

> -		const unsigned chan = i5100_csrow_to_chan(mci, i);

> -		const unsigned rank = i5100_csrow_to_rank(mci, i);

> +	mci_for_each_dimm(mci, dimm) {

> +		const unsigned long npages = i5100_npages(mci, dimm->idx);

> +		const unsigned chan = i5100_csrow_to_chan(mci, dimm->idx);

> +		const unsigned rank = i5100_csrow_to_rank(mci, dimm->idx);

>  

>  		if (!npages)

>  			continue;


This cannot be right: the code here under this does now:

	dimm = edac_get_dimm(mci, chan, rank, 0);

but dimm is already set. It used to get the DIMM using chan and rank but
now you're iterating over the already initialized pointers. So I think
you don't need the edac_get_dimm() anymore.

Also fix those up too, while at it pls:

WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
#235: FILE: drivers/edac/i5100_edac.c:854:
+               const unsigned chan = i5100_csrow_to_chan(mci, dimm->idx);

WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
#236: FILE: drivers/edac/i5100_edac.c:855:
+               const unsigned rank = i5100_csrow_to_rank(mci, dimm->idx);


> diff --git a/include/linux/edac.h b/include/linux/edac.h

> index 2ee9b8598ae0..20a04f48616c 100644

> --- a/include/linux/edac.h

> +++ b/include/linux/edac.h

> @@ -599,6 +599,13 @@ struct mem_ctl_info {

>  	u16 fake_inject_count;

>  };

>  

> +#define mci_for_each_dimm(mci, dimm)			\

> +	for ((dimm) = (mci)->dimms[0];			\

> +	     (dimm);					\

> +	     (dimm) = (dimm)->idx < (mci)->tot_dimms	\

> +		     ? (mci)->dimms[(dimm)->idx + 1]	\

> +		     : NULL)

> +

>  /**

>   * edac_get_dimm_by_index - Get DIMM info from a memory controller

>   *                          given by an index

> -- 


Thx.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.
Robert Richter Aug. 28, 2019, 8:18 a.m. | #2
On 14.08.19 17:18:24, Borislav Petkov wrote:
> On Mon, Jun 24, 2019 at 03:09:11PM +0000, Robert Richter wrote:

> > Make code more readable by introducing a mci_for_each_dimm() iterator.

> > Now, we just get a pointer to a struct dimm_info. Direct array access

> > using an index is no longer needed to iterate.

> > 

> > Signed-off-by: Robert Richter <rrichter@marvell.com>

> > ---

> >  drivers/edac/edac_mc.c       | 18 ++++++++++--------

> >  drivers/edac/edac_mc_sysfs.c | 34 +++++++++++++++-------------------

> >  drivers/edac/ghes_edac.c     |  8 ++++----

> >  drivers/edac/i5100_edac.c    | 11 +++++------

> >  include/linux/edac.h         |  7 +++++++

> >  5 files changed, 41 insertions(+), 37 deletions(-)

> > 

> > diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c

> > index c44bc83e8502..27277ca46ab3 100644

> > --- a/drivers/edac/edac_mc.c

> > +++ b/drivers/edac/edac_mc.c

> > @@ -145,15 +145,18 @@ static void edac_mc_dump_channel(struct rank_info *chan)

> >  	edac_dbg(4, "    channel->dimm = %p\n", chan->dimm);

> >  }

> >  

> > -static void edac_mc_dump_dimm(struct dimm_info *dimm, int number)

> > +static void edac_mc_dump_dimm(struct dimm_info *dimm)

> >  {

> >  	char location[80];

> >  

> > +	if (!dimm->nr_pages)

> > +		return;

> > +

> 

> What's that for?


This is moved from the iterator loop below to here. It limits the dump
to only populated dimm slots.

> 

> >  	edac_dimm_info_location(dimm, location, sizeof(location));

> >  

> >  	edac_dbg(4, "%s%i: %smapped as virtual row %d, chan %d\n",

> >  		 dimm->mci->csbased ? "rank" : "dimm",

> > -		 number, location, dimm->csrow, dimm->cschannel);

> > +		 dimm->idx, location, dimm->csrow, dimm->cschannel);

> >  	edac_dbg(4, "  dimm = %p\n", dimm);

> >  	edac_dbg(4, "  dimm->label = '%s'\n", dimm->label);

> >  	edac_dbg(4, "  dimm->nr_pages = 0x%x\n", dimm->nr_pages);


> > diff --git a/drivers/edac/i5100_edac.c b/drivers/edac/i5100_edac.c

> > index 39ba7f2414ae..7ec42b26a716 100644

> > --- a/drivers/edac/i5100_edac.c

> > +++ b/drivers/edac/i5100_edac.c

> > @@ -846,14 +846,13 @@ static void i5100_init_interleaving(struct pci_dev *pdev,

> >  

> >  static void i5100_init_csrows(struct mem_ctl_info *mci)

> >  {

> > -	int i;

> >  	struct i5100_priv *priv = mci->pvt_info;

> > +	struct dimm_info *dimm;

> >  

> > -	for (i = 0; i < mci->tot_dimms; i++) {

> > -		struct dimm_info *dimm;

> > -		const unsigned long npages = i5100_npages(mci, i);

> > -		const unsigned chan = i5100_csrow_to_chan(mci, i);

> > -		const unsigned rank = i5100_csrow_to_rank(mci, i);

> > +	mci_for_each_dimm(mci, dimm) {

> > +		const unsigned long npages = i5100_npages(mci, dimm->idx);

> > +		const unsigned chan = i5100_csrow_to_chan(mci, dimm->idx);

> > +		const unsigned rank = i5100_csrow_to_rank(mci, dimm->idx);

> >  

> >  		if (!npages)

> >  			continue;

> 

> This cannot be right: the code here under this does now:

> 

> 	dimm = edac_get_dimm(mci, chan, rank, 0);

> 

> but dimm is already set. It used to get the DIMM using chan and rank but

> now you're iterating over the already initialized pointers. So I think

> you don't need the edac_get_dimm() anymore.


Right, it should calculate to the same pointer we already have and can
be removed. Good catch.

> 

> Also fix those up too, while at it pls:

> 

> WARNING: Prefer 'unsigned int' to bare use of 'unsigned'

> #235: FILE: drivers/edac/i5100_edac.c:854:

> +               const unsigned chan = i5100_csrow_to_chan(mci, dimm->idx);

> 

> WARNING: Prefer 'unsigned int' to bare use of 'unsigned'

> #236: FILE: drivers/edac/i5100_edac.c:855:

> +               const unsigned rank = i5100_csrow_to_rank(mci, dimm->idx);


I am going to fix this is a separate patch, though I will exclude
rework of struct i5100_priv.

I have reworked the patch according to all your other comments.

Thanks for review.

-Robert

Patch

diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index c44bc83e8502..27277ca46ab3 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -145,15 +145,18 @@  static void edac_mc_dump_channel(struct rank_info *chan)
 	edac_dbg(4, "    channel->dimm = %p\n", chan->dimm);
 }
 
-static void edac_mc_dump_dimm(struct dimm_info *dimm, int number)
+static void edac_mc_dump_dimm(struct dimm_info *dimm)
 {
 	char location[80];
 
+	if (!dimm->nr_pages)
+		return;
+
 	edac_dimm_info_location(dimm, location, sizeof(location));
 
 	edac_dbg(4, "%s%i: %smapped as virtual row %d, chan %d\n",
 		 dimm->mci->csbased ? "rank" : "dimm",
-		 number, location, dimm->csrow, dimm->cschannel);
+		 dimm->idx, location, dimm->csrow, dimm->cschannel);
 	edac_dbg(4, "  dimm = %p\n", dimm);
 	edac_dbg(4, "  dimm->label = '%s'\n", dimm->label);
 	edac_dbg(4, "  dimm->nr_pages = 0x%x\n", dimm->nr_pages);
@@ -703,6 +706,7 @@  EXPORT_SYMBOL_GPL(edac_get_owner);
 int edac_mc_add_mc_with_groups(struct mem_ctl_info *mci,
 			       const struct attribute_group **groups)
 {
+	struct dimm_info *dimm;
 	int ret = -EINVAL;
 	edac_dbg(0, "\n");
 
@@ -727,9 +731,8 @@  int edac_mc_add_mc_with_groups(struct mem_ctl_info *mci,
 				if (csrow->channels[j]->dimm->nr_pages)
 					edac_mc_dump_channel(csrow->channels[j]);
 		}
-		for (i = 0; i < mci->tot_dimms; i++)
-			if (mci->dimms[i]->nr_pages)
-				edac_mc_dump_dimm(mci->dimms[i], i);
+		mci_for_each_dimm(mci, dimm)
+			edac_mc_dump_dimm(dimm);
 	}
 #endif
 	mutex_lock(&mem_ctls_mutex);
@@ -1104,6 +1107,7 @@  void edac_mc_handle_error(const enum hw_event_mc_err_type type,
 			  const char *msg,
 			  const char *other_detail)
 {
+	struct dimm_info *dimm;
 	char *p;
 	int row = -1, chan = -1;
 	int pos[EDAC_MAX_LAYERS] = { top_layer, mid_layer, low_layer };
@@ -1163,9 +1167,7 @@  void edac_mc_handle_error(const enum hw_event_mc_err_type type,
 	p = e->label;
 	*p = '\0';
 
-	for (i = 0; i < mci->tot_dimms; i++) {
-		struct dimm_info *dimm = mci->dimms[i];
-
+	mci_for_each_dimm(mci, dimm) {
 		if (top_layer >= 0 && top_layer != dimm->location[0])
 			continue;
 		if (mid_layer >= 0 && mid_layer != dimm->location[1])
diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
index a69e99206a6f..4d15c88a52cd 100644
--- a/drivers/edac/edac_mc_sysfs.c
+++ b/drivers/edac/edac_mc_sysfs.c
@@ -623,8 +623,7 @@  static const struct device_type dimm_attr_type = {
 
 /* Create a DIMM object under specifed memory controller device */
 static int edac_create_dimm_object(struct mem_ctl_info *mci,
-				   struct dimm_info *dimm,
-				   int index)
+				   struct dimm_info *dimm)
 {
 	int err;
 	dimm->mci = mci;
@@ -634,9 +633,9 @@  static int edac_create_dimm_object(struct mem_ctl_info *mci,
 
 	dimm->dev.parent = &mci->dev;
 	if (mci->csbased)
-		dev_set_name(&dimm->dev, "rank%d", index);
+		dev_set_name(&dimm->dev, "rank%d", dimm->idx);
 	else
-		dev_set_name(&dimm->dev, "dimm%d", index);
+		dev_set_name(&dimm->dev, "dimm%d", dimm->idx);
 	dev_set_drvdata(&dimm->dev, dimm);
 	pm_runtime_forbid(&mci->dev);
 
@@ -910,7 +909,8 @@  static const struct device_type mci_attr_type = {
 int edac_create_sysfs_mci_device(struct mem_ctl_info *mci,
 				 const struct attribute_group **groups)
 {
-	int i, err;
+	struct dimm_info *dimm;
+	int err;
 
 	/* get the /sys/devices/system/edac subsys reference */
 	mci->dev.type = &mci_attr_type;
@@ -933,14 +933,13 @@  int edac_create_sysfs_mci_device(struct mem_ctl_info *mci,
 	/*
 	 * Create the dimm/rank devices
 	 */
-	for (i = 0; i < mci->tot_dimms; i++) {
-		struct dimm_info *dimm = mci->dimms[i];
+	mci_for_each_dimm(mci, dimm) {
 		/* Only expose populated DIMMs */
 		if (!dimm->nr_pages)
 			continue;
 
 #ifdef CONFIG_EDAC_DEBUG
-		edac_dbg(1, "creating dimm%d, located at ", i);
+		edac_dbg(1, "creating dimm%d, located at ", dimm->idx);
 		if (edac_debug_level >= 1) {
 			int lay;
 			for (lay = 0; lay < mci->n_layers; lay++)
@@ -950,9 +949,10 @@  int edac_create_sysfs_mci_device(struct mem_ctl_info *mci,
 			printk(KERN_CONT "\n");
 		}
 #endif
-		err = edac_create_dimm_object(mci, dimm, i);
+		err = edac_create_dimm_object(mci, dimm);
 		if (err) {
-			edac_dbg(1, "failure: create dimm %d obj\n", i);
+			edac_dbg(1, "failure: create dimm %d obj\n",
+				dimm->idx);
 			goto fail_unregister_dimm;
 		}
 	}
@@ -967,12 +967,9 @@  int edac_create_sysfs_mci_device(struct mem_ctl_info *mci,
 	return 0;
 
 fail_unregister_dimm:
-	for (i--; i >= 0; i--) {
-		struct dimm_info *dimm = mci->dimms[i];
-		if (!dimm->nr_pages)
-			continue;
-
-		device_unregister(&dimm->dev);
+	mci_for_each_dimm(mci, dimm) {
+		if (device_is_registered(&dimm->dev))
+			device_unregister(&dimm->dev);
 	}
 	device_unregister(&mci->dev);
 
@@ -984,7 +981,7 @@  int edac_create_sysfs_mci_device(struct mem_ctl_info *mci,
  */
 void edac_remove_sysfs_mci_device(struct mem_ctl_info *mci)
 {
-	int i;
+	struct dimm_info *dimm;
 
 	edac_dbg(0, "\n");
 
@@ -995,8 +992,7 @@  void edac_remove_sysfs_mci_device(struct mem_ctl_info *mci)
 	edac_delete_csrow_objects(mci);
 #endif
 
-	for (i = 0; i < mci->tot_dimms; i++) {
-		struct dimm_info *dimm = mci->dimms[i];
+	mci_for_each_dimm(mci, dimm) {
 		if (dimm->nr_pages == 0)
 			continue;
 		edac_dbg(0, "removing device %s\n", dev_name(&dimm->dev));
diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
index 8050f9577fe6..72e75ea5526c 100644
--- a/drivers/edac/ghes_edac.c
+++ b/drivers/edac/ghes_edac.c
@@ -81,11 +81,11 @@  static void ghes_edac_count_dimms(const struct dmi_header *dh, void *arg)
 static int get_dimm_smbios_index(u16 handle)
 {
 	struct mem_ctl_info *mci = ghes_pvt->mci;
-	int i;
+	struct dimm_info *dimm;
 
-	for (i = 0; i < mci->tot_dimms; i++) {
-		if (mci->dimms[i]->smbios_handle == handle)
-			return i;
+	mci_for_each_dimm(mci, dimm) {
+		if (dimm->smbios_handle == handle)
+			return dimm->idx;
 	}
 	return -1;
 }
diff --git a/drivers/edac/i5100_edac.c b/drivers/edac/i5100_edac.c
index 39ba7f2414ae..7ec42b26a716 100644
--- a/drivers/edac/i5100_edac.c
+++ b/drivers/edac/i5100_edac.c
@@ -846,14 +846,13 @@  static void i5100_init_interleaving(struct pci_dev *pdev,
 
 static void i5100_init_csrows(struct mem_ctl_info *mci)
 {
-	int i;
 	struct i5100_priv *priv = mci->pvt_info;
+	struct dimm_info *dimm;
 
-	for (i = 0; i < mci->tot_dimms; i++) {
-		struct dimm_info *dimm;
-		const unsigned long npages = i5100_npages(mci, i);
-		const unsigned chan = i5100_csrow_to_chan(mci, i);
-		const unsigned rank = i5100_csrow_to_rank(mci, i);
+	mci_for_each_dimm(mci, dimm) {
+		const unsigned long npages = i5100_npages(mci, dimm->idx);
+		const unsigned chan = i5100_csrow_to_chan(mci, dimm->idx);
+		const unsigned rank = i5100_csrow_to_rank(mci, dimm->idx);
 
 		if (!npages)
 			continue;
diff --git a/include/linux/edac.h b/include/linux/edac.h
index 2ee9b8598ae0..20a04f48616c 100644
--- a/include/linux/edac.h
+++ b/include/linux/edac.h
@@ -599,6 +599,13 @@  struct mem_ctl_info {
 	u16 fake_inject_count;
 };
 
+#define mci_for_each_dimm(mci, dimm)			\
+	for ((dimm) = (mci)->dimms[0];			\
+	     (dimm);					\
+	     (dimm) = (dimm)->idx < (mci)->tot_dimms	\
+		     ? (mci)->dimms[(dimm)->idx + 1]	\
+		     : NULL)
+
 /**
  * edac_get_dimm_by_index - Get DIMM info from a memory controller
  *                          given by an index