[11/17] mm: move get_dev_pagemap out of line

Commit Message

Christoph Hellwig Dec. 15, 2017, 2:09 p.m. UTC

This is a pretty big function, which should be out of line in general,
and a no-op stub if CONFIG_ZONE_DEVICЕ is not set.

Signed-off-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Logan Gunthorpe <[e-mail]>
---
 include/linux/memremap.h | 39 ++++-----------------------------------
 kernel/memremap.c        | 36 ++++++++++++++++++++++++++++++++++--
 2 files changed, 38 insertions(+), 37 deletions(-)

Comments

Dan Williams Dec. 17, 2017, 5:26 p.m. UTC | #1

On Fri, Dec 15, 2017 at 6:09 AM, Christoph Hellwig <[e-mail]> wrote:
> This is a pretty big function, which should be out of line in general,
> and a no-op stub if CONFIG_ZONE_DEVICЕ is not set.
>
> Signed-off-by: Christoph Hellwig <[e-mail]>
> Reviewed-by: Logan Gunthorpe <[e-mail]>
[..]
> +/**
> + * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
> + * @pfn: page frame number to lookup page_map
> + * @pgmap: optional known pgmap that already has a reference
> + *
> + * @pgmap allows the overhead of a lookup to be bypassed when @pfn lands in the
> + * same mapping.
> + */
> +struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
> +               struct dev_pagemap *pgmap)
> +{
> +       const struct resource *res = pgmap ? pgmap->res : NULL;
> +       resource_size_t phys = PFN_PHYS(pfn);
> +
> +       /*
> +        * In the cached case we're already holding a live reference so
> +        * we can simply do a blind increment
> +        */
> +       if (res && phys >= res->start && phys <= res->end) {
> +               percpu_ref_get(pgmap->ref);
> +               return pgmap;
> +       }

I was going to say keep the cached case in the static inline, but with
the optimization to the calling convention in the following patch I
think that makes this moot.

So,

Reviewed-by: Dan Williams <[e-mail]>

Patch

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index d5a6736d9737..26e8aaba27d5 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -133,7 +133,8 @@  struct dev_pagemap {
 #ifdef CONFIG_ZONE_DEVICE
 void *devm_memremap_pages(struct device *dev, struct resource *res,
 		struct percpu_ref *ref, struct vmem_altmap *altmap);
-struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
+struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
+		struct dev_pagemap *pgmap);
 
 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
@@ -153,7 +154,8 @@  static inline void *devm_memremap_pages(struct device *dev,
 	return ERR_PTR(-ENXIO);
 }
 
-static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
+static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
+		struct dev_pagemap *pgmap)
 {
 	return NULL;
 }
@@ -183,39 +185,6 @@  static inline bool is_device_public_page(const struct page *page)
 }
 #endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
 
-/**
- * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
- * @pfn: page frame number to lookup page_map
- * @pgmap: optional known pgmap that already has a reference
- *
- * @pgmap allows the overhead of a lookup to be bypassed when @pfn lands in the
- * same mapping.
- */
-static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
-		struct dev_pagemap *pgmap)
-{
-	const struct resource *res = pgmap ? pgmap->res : NULL;
-	resource_size_t phys = PFN_PHYS(pfn);
-
-	/*
-	 * In the cached case we're already holding a live reference so
-	 * we can simply do a blind increment
-	 */
-	if (res && phys >= res->start && phys <= res->end) {
-		percpu_ref_get(pgmap->ref);
-		return pgmap;
-	}
-
-	/* fall back to slow path lookup */
-	rcu_read_lock();
-	pgmap = find_dev_pagemap(phys);
-	if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
-		pgmap = NULL;
-	rcu_read_unlock();
-
-	return pgmap;
-}
-
 static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
 {
 	if (pgmap)
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 8e85803b6b0e..43d94db97ff4 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -314,7 +314,7 @@  static void devm_memremap_pages_release(struct device *dev, void *data)
 }
 
 /* assumes rcu_read_lock() held at entry */
-struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
+static struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
 {
 	struct page_map *page_map;
 
@@ -500,8 +500,40 @@  struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
 
 	return pgmap ? pgmap->altmap : NULL;
 }
-#endif /* CONFIG_ZONE_DEVICE */
 
+/**
+ * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
+ * @pfn: page frame number to lookup page_map
+ * @pgmap: optional known pgmap that already has a reference
+ *
+ * @pgmap allows the overhead of a lookup to be bypassed when @pfn lands in the
+ * same mapping.
+ */
+struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
+		struct dev_pagemap *pgmap)
+{
+	const struct resource *res = pgmap ? pgmap->res : NULL;
+	resource_size_t phys = PFN_PHYS(pfn);
+
+	/*
+	 * In the cached case we're already holding a live reference so
+	 * we can simply do a blind increment
+	 */
+	if (res && phys >= res->start && phys <= res->end) {
+		percpu_ref_get(pgmap->ref);
+		return pgmap;
+	}
+
+	/* fall back to slow path lookup */
+	rcu_read_lock();
+	pgmap = find_dev_pagemap(phys);
+	if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
+		pgmap = NULL;
+	rcu_read_unlock();
+
+	return pgmap;
+}
+#endif /* CONFIG_ZONE_DEVICE */
 
 #if IS_ENABLED(CONFIG_DEVICE_PRIVATE) ||  IS_ENABLED(CONFIG_DEVICE_PUBLIC)
 void put_zone_device_private_or_public_page(struct page *page)