Since different memory devices require finding, allocating, and putting
memory types, these common steps are abstracted in this patch,
enhancing the scalability and conciseness of the code.

Signed-off-by: Ho-Ren (Jack) Chuang <horenchuang@bytedance.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
---
 drivers/dax/kmem.c           | 20 ++------------------
 include/linux/memory-tiers.h | 13 +++++++++++++
 mm/memory-tiers.c            | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 18 deletions(-)

diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 42ee360cf4e3..01399e5b53b2 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -55,21 +55,10 @@ static LIST_HEAD(kmem_memory_types);
 
 static struct memory_dev_type *kmem_find_alloc_memory_type(int adist)
 {
-	bool found = false;
 	struct memory_dev_type *mtype;
 
 	mutex_lock(&kmem_memory_type_lock);
-	list_for_each_entry(mtype, &kmem_memory_types, list) {
-		if (mtype->adistance == adist) {
-			found = true;
-			break;
-		}
-	}
-	if (!found) {
-		mtype = alloc_memory_type(adist);
-		if (!IS_ERR(mtype))
-			list_add(&mtype->list, &kmem_memory_types);
-	}
+	mtype = mt_find_alloc_memory_type(adist, &kmem_memory_types);
 	mutex_unlock(&kmem_memory_type_lock);
 
 	return mtype;
@@ -77,13 +66,8 @@ static struct memory_dev_type *kmem_find_alloc_memory_type(int adist)
 
 static void kmem_put_memory_types(void)
 {
-	struct memory_dev_type *mtype, *mtn;
-
 	mutex_lock(&kmem_memory_type_lock);
-	list_for_each_entry_safe(mtype, mtn, &kmem_memory_types, list) {
-		list_del(&mtype->list);
-		put_memory_type(mtype);
-	}
+	mt_put_memory_types(&kmem_memory_types);
 	mutex_unlock(&kmem_memory_type_lock);
 }
 
diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
index 69e781900082..a44c03c2ba3a 100644
--- a/include/linux/memory-tiers.h
+++ b/include/linux/memory-tiers.h
@@ -48,6 +48,9 @@ int mt_calc_adistance(int node, int *adist);
 int mt_set_default_dram_perf(int nid, struct access_coordinate *perf,
 			     const char *source);
 int mt_perf_to_adistance(struct access_coordinate *perf, int *adist);
+struct memory_dev_type *mt_find_alloc_memory_type(int adist,
+							struct list_head *memory_types);
+void mt_put_memory_types(struct list_head *memory_types);
 #ifdef CONFIG_MIGRATION
 int next_demotion_node(int node);
 void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets);
@@ -136,5 +139,15 @@ static inline int mt_perf_to_adistance(struct access_coordinate *perf, int *adis
 {
 	return -EIO;
 }
+
+struct memory_dev_type *mt_find_alloc_memory_type(int adist, struct list_head *memory_types)
+{
+	return NULL;
+}
+
+void mt_put_memory_types(struct list_head *memory_types)
+{
+
+}
 #endif	/* CONFIG_NUMA */
 #endif  /* _LINUX_MEMORY_TIERS_H */
diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
index 0537664620e5..974af10cfdd8 100644
--- a/mm/memory-tiers.c
+++ b/mm/memory-tiers.c
@@ -623,6 +623,38 @@ void clear_node_memory_type(int node, struct memory_dev_type *memtype)
 }
 EXPORT_SYMBOL_GPL(clear_node_memory_type);
 
+struct memory_dev_type *mt_find_alloc_memory_type(int adist, struct list_head *memory_types)
+{
+	bool found = false;
+	struct memory_dev_type *mtype;
+
+	list_for_each_entry(mtype, memory_types, list) {
+		if (mtype->adistance == adist) {
+			found = true;
+			break;
+		}
+	}
+	if (!found) {
+		mtype = alloc_memory_type(adist);
+		if (!IS_ERR(mtype))
+			list_add(&mtype->list, memory_types);
+	}
+
+	return mtype;
+}
+EXPORT_SYMBOL_GPL(mt_find_alloc_memory_type);
+
+void mt_put_memory_types(struct list_head *memory_types)
+{
+	struct memory_dev_type *mtype, *mtn;
+
+	list_for_each_entry_safe(mtype, mtn, memory_types, list) {
+		list_del(&mtype->list);
+		put_memory_type(mtype);
+	}
+}
+EXPORT_SYMBOL_GPL(mt_put_memory_types);
+
 static void dump_hmem_attrs(struct access_coordinate *coord, const char *prefix)
 {
 	pr_info(
-- 
Ho-Ren (Jack) Chuang

On Tue,  2 Apr 2024 00:17:37 +0000
"Ho-Ren (Jack) Chuang" <horenchuang@bytedance.com> wrote:

> Since different memory devices require finding, allocating, and putting
> memory types, these common steps are abstracted in this patch,
> enhancing the scalability and conciseness of the code.
> 
> Signed-off-by: Ho-Ren (Jack) Chuang <horenchuang@bytedance.com>
> Reviewed-by: "Huang, Ying" <ying.huang@intel.com>

Hi,

I know this is a late entry to the discussion but a few comments inline.
(sorry I didn't look earlier!)

All opportunities to improve code complexity and readability as a result
of your factoring out.

Jonathan


> ---
>  drivers/dax/kmem.c           | 20 ++------------------
>  include/linux/memory-tiers.h | 13 +++++++++++++
>  mm/memory-tiers.c            | 32 ++++++++++++++++++++++++++++++++
>  3 files changed, 47 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
> index 42ee360cf4e3..01399e5b53b2 100644
> --- a/drivers/dax/kmem.c
> +++ b/drivers/dax/kmem.c
> @@ -55,21 +55,10 @@ static LIST_HEAD(kmem_memory_types);
>  
>  static struct memory_dev_type *kmem_find_alloc_memory_type(int adist)
>  {
> -	bool found = false;
>  	struct memory_dev_type *mtype;
>  
>  	mutex_lock(&kmem_memory_type_lock);
could use

	guard(mutex)(&kmem_memory_type_lock);
	return mt_find_alloc_memory_type(adist, &kmem_memory_types);

I'm fine if you ignore this comment though as may be other functions in
here that could take advantage of the cleanup.h stuff in a future patch.

> -	list_for_each_entry(mtype, &kmem_memory_types, list) {
> -		if (mtype->adistance == adist) {
> -			found = true;
> -			break;
> -		}
> -	}
> -	if (!found) {
> -		mtype = alloc_memory_type(adist);
> -		if (!IS_ERR(mtype))
> -			list_add(&mtype->list, &kmem_memory_types);
> -	}
> +	mtype = mt_find_alloc_memory_type(adist, &kmem_memory_types);
>  	mutex_unlock(&kmem_memory_type_lock);
>  
>  	return mtype;
 
> diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
> index 69e781900082..a44c03c2ba3a 100644
> --- a/include/linux/memory-tiers.h
> +++ b/include/linux/memory-tiers.h
> @@ -48,6 +48,9 @@ int mt_calc_adistance(int node, int *adist);
>  int mt_set_default_dram_perf(int nid, struct access_coordinate *perf,
>  			     const char *source);
>  int mt_perf_to_adistance(struct access_coordinate *perf, int *adist);
> +struct memory_dev_type *mt_find_alloc_memory_type(int adist,
> +							struct list_head *memory_types);

That indent looks unusual.  Align the start of struct with start of int.

> +void mt_put_memory_types(struct list_head *memory_types);
>  #ifdef CONFIG_MIGRATION
>  int next_demotion_node(int node);
>  void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets);
> @@ -136,5 +139,15 @@ static inline int mt_perf_to_adistance(struct access_coordinate *perf, int *adis
>  {
>  	return -EIO;
>  }
> +
> +struct memory_dev_type *mt_find_alloc_memory_type(int adist, struct list_head *memory_types)
> +{
> +	return NULL;
> +}
> +
> +void mt_put_memory_types(struct list_head *memory_types)
> +{
> +
No blank line needed here. 
> +}
>  #endif	/* CONFIG_NUMA */
>  #endif  /* _LINUX_MEMORY_TIERS_H */
> diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
> index 0537664620e5..974af10cfdd8 100644
> --- a/mm/memory-tiers.c
> +++ b/mm/memory-tiers.c
> @@ -623,6 +623,38 @@ void clear_node_memory_type(int node, struct memory_dev_type *memtype)
>  }
>  EXPORT_SYMBOL_GPL(clear_node_memory_type);
>  
> +struct memory_dev_type *mt_find_alloc_memory_type(int adist, struct list_head *memory_types)

Breaking this out as a separate function provides opportunity to improve it.
Maybe a follow up patch makes sense given it would no longer be a straight
forward code move.  However in my view it would be simple enough to be obvious
even within this patch.

> +{
> +	bool found = false;
> +	struct memory_dev_type *mtype;
> +
> +	list_for_each_entry(mtype, memory_types, list) {
> +		if (mtype->adistance == adist) {
> +			found = true;

Why not return here?
			return mtype;

> +			break;
> +		}
> +	}
> +	if (!found) {

If returning above, no need for found variable - just do this unconditionally.
+ I suggest you flip logic for simpler to follow code flow.
It's more code but I think a bit easier to read as error handling is
out of the main simple flow.

	mtype = alloc_memory_type(adist);
	if (IS_ERR(mtype))
		return mtype;

	list_add(&mtype->list, memory_types);

	return mtype;

> +		mtype = alloc_memory_type(adist);
> +		if (!IS_ERR(mtype))
> +			list_add(&mtype->list, memory_types);
> +	}
> +
> +	return mtype;
> +}
> +EXPORT_SYMBOL_GPL(mt_find_alloc_memory_type);
> +
> +void mt_put_memory_types(struct list_head *memory_types)
> +{
> +	struct memory_dev_type *mtype, *mtn;
> +
> +	list_for_each_entry_safe(mtype, mtn, memory_types, list) {
> +		list_del(&mtype->list);
> +		put_memory_type(mtype);
> +	}
> +}
> +EXPORT_SYMBOL_GPL(mt_put_memory_types);
> +
>  static void dump_hmem_attrs(struct access_coordinate *coord, const char *prefix)
>  {
>  	pr_info(

Hi Jonathan,

Thanks for your feedback. I will fix them (inlined) in the next V11.
No worries, it's never too late!

On Wed, Apr 3, 2024 at 9:52 AM Jonathan Cameron
<Jonathan.Cameron@huawei.com> wrote:
>
> On Tue,  2 Apr 2024 00:17:37 +0000
> "Ho-Ren (Jack) Chuang" <horenchuang@bytedance.com> wrote:
>
> > Since different memory devices require finding, allocating, and putting
> > memory types, these common steps are abstracted in this patch,
> > enhancing the scalability and conciseness of the code.
> >
> > Signed-off-by: Ho-Ren (Jack) Chuang <horenchuang@bytedance.com>
> > Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
>
> Hi,
>
> I know this is a late entry to the discussion but a few comments inline.
> (sorry I didn't look earlier!)
>
> All opportunities to improve code complexity and readability as a result
> of your factoring out.
>
> Jonathan
>
>
> > ---
> >  drivers/dax/kmem.c           | 20 ++------------------
> >  include/linux/memory-tiers.h | 13 +++++++++++++
> >  mm/memory-tiers.c            | 32 ++++++++++++++++++++++++++++++++
> >  3 files changed, 47 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
> > index 42ee360cf4e3..01399e5b53b2 100644
> > --- a/drivers/dax/kmem.c
> > +++ b/drivers/dax/kmem.c
> > @@ -55,21 +55,10 @@ static LIST_HEAD(kmem_memory_types);
> >
> >  static struct memory_dev_type *kmem_find_alloc_memory_type(int adist)
> >  {
> > -     bool found = false;
> >       struct memory_dev_type *mtype;
> >
> >       mutex_lock(&kmem_memory_type_lock);
> could use
>
>         guard(mutex)(&kmem_memory_type_lock);
>         return mt_find_alloc_memory_type(adist, &kmem_memory_types);
>

I will change it accordingly.

> I'm fine if you ignore this comment though as may be other functions in
> here that could take advantage of the cleanup.h stuff in a future patch.
>
> > -     list_for_each_entry(mtype, &kmem_memory_types, list) {
> > -             if (mtype->adistance == adist) {
> > -                     found = true;
> > -                     break;
> > -             }
> > -     }
> > -     if (!found) {
> > -             mtype = alloc_memory_type(adist);
> > -             if (!IS_ERR(mtype))
> > -                     list_add(&mtype->list, &kmem_memory_types);
> > -     }
> > +     mtype = mt_find_alloc_memory_type(adist, &kmem_memory_types);
> >       mutex_unlock(&kmem_memory_type_lock);
> >
> >       return mtype;
>
> > diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
> > index 69e781900082..a44c03c2ba3a 100644
> > --- a/include/linux/memory-tiers.h
> > +++ b/include/linux/memory-tiers.h
> > @@ -48,6 +48,9 @@ int mt_calc_adistance(int node, int *adist);
> >  int mt_set_default_dram_perf(int nid, struct access_coordinate *perf,
> >                            const char *source);
> >  int mt_perf_to_adistance(struct access_coordinate *perf, int *adist);
> > +struct memory_dev_type *mt_find_alloc_memory_type(int adist,
> > +                                                     struct list_head *memory_types);
>
> That indent looks unusual.  Align the start of struct with start of int.
>

I can make this aligned but it will show another warning:
"WARNING: line length of 131 exceeds 100 columns"
Is this ok?

> > +void mt_put_memory_types(struct list_head *memory_types);
> >  #ifdef CONFIG_MIGRATION
> >  int next_demotion_node(int node);
> >  void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets);
> > @@ -136,5 +139,15 @@ static inline int mt_perf_to_adistance(struct access_coordinate *perf, int *adis
> >  {
> >       return -EIO;
> >  }
> > +
> > +struct memory_dev_type *mt_find_alloc_memory_type(int adist, struct list_head *memory_types)
> > +{
> > +     return NULL;
> > +}
> > +
> > +void mt_put_memory_types(struct list_head *memory_types)
> > +{
> > +
> No blank line needed here.

Will fix.

> > +}
> >  #endif       /* CONFIG_NUMA */
> >  #endif  /* _LINUX_MEMORY_TIERS_H */
> > diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
> > index 0537664620e5..974af10cfdd8 100644
> > --- a/mm/memory-tiers.c
> > +++ b/mm/memory-tiers.c
> > @@ -623,6 +623,38 @@ void clear_node_memory_type(int node, struct memory_dev_type *memtype)
> >  }
> >  EXPORT_SYMBOL_GPL(clear_node_memory_type);
> >
> > +struct memory_dev_type *mt_find_alloc_memory_type(int adist, struct list_head *memory_types)
>
> Breaking this out as a separate function provides opportunity to improve it.
> Maybe a follow up patch makes sense given it would no longer be a straight
> forward code move.  However in my view it would be simple enough to be obvious
> even within this patch.
>

I will just keep this as is for now to minimize the changes aka mistakes.

> > +{
> > +     bool found = false;
> > +     struct memory_dev_type *mtype;
> > +
> > +     list_for_each_entry(mtype, memory_types, list) {
> > +             if (mtype->adistance == adist) {
> > +                     found = true;
>
> Why not return here?
>                         return mtype;
>

Yes, I can return here. I will do that and take care of the ptr
returning at this point.

> > +                     break;
> > +             }
> > +     }
> > +     if (!found) {
>
> If returning above, no need for found variable - just do this unconditionally.
> + I suggest you flip logic for simpler to follow code flow.
> It's more code but I think a bit easier to read as error handling is
> out of the main simple flow.
>
>         mtype = alloc_memory_type(adist);
>         if (IS_ERR(mtype))
>                 return mtype;
>
>         list_add(&mtype->list, memory_types);
>
>         return mtype;
>

Good idea! I will change it accordingly.

> > +             mtype = alloc_memory_type(adist);
> > +             if (!IS_ERR(mtype))
> > +                     list_add(&mtype->list, memory_types);
> > +     }
> > +
> > +     return mtype;
> > +}
> > +EXPORT_SYMBOL_GPL(mt_find_alloc_memory_type);
> > +
> > +void mt_put_memory_types(struct list_head *memory_types)
> > +{
> > +     struct memory_dev_type *mtype, *mtn;
> > +
> > +     list_for_each_entry_safe(mtype, mtn, memory_types, list) {
> > +             list_del(&mtype->list);
> > +             put_memory_type(mtype);
> > +     }
> > +}
> > +EXPORT_SYMBOL_GPL(mt_put_memory_types);
> > +
> >  static void dump_hmem_attrs(struct access_coordinate *coord, const char *prefix)
> >  {
> >       pr_info(
>


-- 
Best regards,
Ho-Ren (Jack) Chuang
莊賀任