diff mbox series

[06/11] drm/i915: use vmap in shmem_pin_map

Message ID 20200924135853.875294-7-hch@lst.de (mailing list archive)
State New, archived
Headers show
Series [01/11] mm: update the documentation for vfree | expand

Commit Message

Christoph Hellwig Sept. 24, 2020, 1:58 p.m. UTC 
shmem_pin_map somewhat awkwardly reimplements vmap using
alloc_vm_area and manual pte setup.  The only practical difference
is that alloc_vm_area prefeaults the vmalloc area PTEs, which doesn't
seem to be required here (and could be added to vmap using a flag if
actually required).  Switch to use vmap, and use vfree to free both the
vmalloc mapping and the page array, as well as dropping the references
to each page.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/gpu/drm/i915/gt/shmem_utils.c | 76 +++++++--------------------
 1 file changed, 18 insertions(+), 58 deletions(-)

Comments

Tvrtko Ursulin Sept. 25, 2020, 1:05 p.m. UTC | #1 
On 24/09/2020 14:58, Christoph Hellwig wrote:
> shmem_pin_map somewhat awkwardly reimplements vmap using
> alloc_vm_area and manual pte setup.  The only practical difference
> is that alloc_vm_area prefeaults the vmalloc area PTEs, which doesn't
> seem to be required here (and could be added to vmap using a flag if
> actually required).  Switch to use vmap, and use vfree to free both the
> vmalloc mapping and the page array, as well as dropping the references
> to each page.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/gpu/drm/i915/gt/shmem_utils.c | 76 +++++++--------------------
>   1 file changed, 18 insertions(+), 58 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/shmem_utils.c b/drivers/gpu/drm/i915/gt/shmem_utils.c
> index 43c7acbdc79dea..f011ea42487e11 100644
> --- a/drivers/gpu/drm/i915/gt/shmem_utils.c
> +++ b/drivers/gpu/drm/i915/gt/shmem_utils.c
> @@ -49,80 +49,40 @@ struct file *shmem_create_from_object(struct drm_i915_gem_object *obj)
>   	return file;
>   }
>   
> -static size_t shmem_npte(struct file *file)
> -{
> -	return file->f_mapping->host->i_size >> PAGE_SHIFT;
> -}
> -
> -static void __shmem_unpin_map(struct file *file, void *ptr, size_t n_pte)
> -{
> -	unsigned long pfn;
> -
> -	vunmap(ptr);
> -
> -	for (pfn = 0; pfn < n_pte; pfn++) {
> -		struct page *page;
> -
> -		page = shmem_read_mapping_page_gfp(file->f_mapping, pfn,
> -						   GFP_KERNEL);
> -		if (!WARN_ON(IS_ERR(page))) {
> -			put_page(page);
> -			put_page(page);
> -		}
> -	}
> -}
> -
>   void *shmem_pin_map(struct file *file)
>   {
> -	const size_t n_pte = shmem_npte(file);
> -	pte_t *stack[32], **ptes, **mem;
> -	struct vm_struct *area;
> -	unsigned long pfn;
> -
> -	mem = stack;
> -	if (n_pte > ARRAY_SIZE(stack)) {
> -		mem = kvmalloc_array(n_pte, sizeof(*mem), GFP_KERNEL);
> -		if (!mem)
> -			return NULL;
> -	}
> +	struct page **pages;
> +	size_t n_pages, i;
> +	void *vaddr;
>   
> -	area = alloc_vm_area(n_pte << PAGE_SHIFT, mem);
> -	if (!area) {
> -		if (mem != stack)
> -			kvfree(mem);
> +	n_pages = file->f_mapping->host->i_size >> PAGE_SHIFT;
> +	pages = kvmalloc_array(n_pages, sizeof(*pages), GFP_KERNEL);
> +	if (!pages)
>   		return NULL;
> -	}
>   
> -	ptes = mem;
> -	for (pfn = 0; pfn < n_pte; pfn++) {
> -		struct page *page;
> -
> -		page = shmem_read_mapping_page_gfp(file->f_mapping, pfn,
> -						   GFP_KERNEL);
> -		if (IS_ERR(page))
> +	for (i = 0; i < n_pages; i++) {
> +		pages[i] = shmem_read_mapping_page_gfp(file->f_mapping, i,
> +						       GFP_KERNEL);
> +		if (IS_ERR(pages[i]))
>   			goto err_page;
> -
> -		**ptes++ = mk_pte(page,  PAGE_KERNEL);
>   	}
>   
> -	if (mem != stack)
> -		kvfree(mem);
> -
> +	vaddr = vmap(pages, n_pages, VM_MAP_PUT_PAGES, PAGE_KERNEL);
> +	if (!vaddr)
> +		goto err_page;
>   	mapping_set_unevictable(file->f_mapping);
> -	return area->addr;
> -
> +	return vaddr;
>   err_page:
> -	if (mem != stack)
> -		kvfree(mem);
> -
> -	__shmem_unpin_map(file, area->addr, pfn);
> +	while (--i >= 0)
> +		put_page(pages[i]);
> +	kvfree(pages);
>   	return NULL;
>   }
>   
>   void shmem_unpin_map(struct file *file, void *ptr)
>   {
>   	mapping_clear_unevictable(file->f_mapping);
> -	__shmem_unpin_map(file, ptr, shmem_npte(file));
> +	vfree(ptr);
>   }
>   
>   static int __shmem_rw(struct file *file, loff_t off,
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/gt/shmem_utils.c b/drivers/gpu/drm/i915/gt/shmem_utils.c
index 43c7acbdc79dea..f011ea42487e11 100644
--- a/drivers/gpu/drm/i915/gt/shmem_utils.c
+++ b/drivers/gpu/drm/i915/gt/shmem_utils.c
@@ -49,80 +49,40 @@  struct file *shmem_create_from_object(struct drm_i915_gem_object *obj)
 	return file;
 }
 
-static size_t shmem_npte(struct file *file)
-{
-	return file->f_mapping->host->i_size >> PAGE_SHIFT;
-}
-
-static void __shmem_unpin_map(struct file *file, void *ptr, size_t n_pte)
-{
-	unsigned long pfn;
-
-	vunmap(ptr);
-
-	for (pfn = 0; pfn < n_pte; pfn++) {
-		struct page *page;
-
-		page = shmem_read_mapping_page_gfp(file->f_mapping, pfn,
-						   GFP_KERNEL);
-		if (!WARN_ON(IS_ERR(page))) {
-			put_page(page);
-			put_page(page);
-		}
-	}
-}
-
 void *shmem_pin_map(struct file *file)
 {
-	const size_t n_pte = shmem_npte(file);
-	pte_t *stack[32], **ptes, **mem;
-	struct vm_struct *area;
-	unsigned long pfn;
-
-	mem = stack;
-	if (n_pte > ARRAY_SIZE(stack)) {
-		mem = kvmalloc_array(n_pte, sizeof(*mem), GFP_KERNEL);
-		if (!mem)
-			return NULL;
-	}
+	struct page **pages;
+	size_t n_pages, i;
+	void *vaddr;
 
-	area = alloc_vm_area(n_pte << PAGE_SHIFT, mem);
-	if (!area) {
-		if (mem != stack)
-			kvfree(mem);
+	n_pages = file->f_mapping->host->i_size >> PAGE_SHIFT;
+	pages = kvmalloc_array(n_pages, sizeof(*pages), GFP_KERNEL);
+	if (!pages)
 		return NULL;
-	}
 
-	ptes = mem;
-	for (pfn = 0; pfn < n_pte; pfn++) {
-		struct page *page;
-
-		page = shmem_read_mapping_page_gfp(file->f_mapping, pfn,
-						   GFP_KERNEL);
-		if (IS_ERR(page))
+	for (i = 0; i < n_pages; i++) {
+		pages[i] = shmem_read_mapping_page_gfp(file->f_mapping, i,
+						       GFP_KERNEL);
+		if (IS_ERR(pages[i]))
 			goto err_page;
-
-		**ptes++ = mk_pte(page,  PAGE_KERNEL);
 	}
 
-	if (mem != stack)
-		kvfree(mem);
-
+	vaddr = vmap(pages, n_pages, VM_MAP_PUT_PAGES, PAGE_KERNEL);
+	if (!vaddr)
+		goto err_page;
 	mapping_set_unevictable(file->f_mapping);
-	return area->addr;
-
+	return vaddr;
 err_page:
-	if (mem != stack)
-		kvfree(mem);
-
-	__shmem_unpin_map(file, area->addr, pfn);
+	while (--i >= 0)
+		put_page(pages[i]);
+	kvfree(pages);
 	return NULL;
 }
 
 void shmem_unpin_map(struct file *file, void *ptr)
 {
 	mapping_clear_unevictable(file->f_mapping);
-	__shmem_unpin_map(file, ptr, shmem_npte(file));
+	vfree(ptr);
 }
 
 static int __shmem_rw(struct file *file, loff_t off,