On Tue, Feb 08, 2022 at 02:45:09AM -0800, Lucas De Marchi wrote:
> Add a variant of shmem_read() that takes a iosys_map pointer rather
> than a plain pointer as argument. It's mostly a copy __shmem_rw() but
> adapting the api and removing the write support since there's currently
> only need to use iosys_map as destination.
>
> Reworking __shmem_rw() to share the implementation was tempting, but
> finding a good balance between reuse and clarity pushed towards a little
> code duplication. Since the function is small, just add the similar
> function with a copy/paste/adapt approach.
>
> v2: Add an offset as argument and instead of using a map iterator, use the
> offset to keep track of where we are writing data to.
>
> Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Reviewed-by: Matt Atwood <matthew.s.atwood@xxxxxxxxx>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gt/shmem_utils.c | 32 +++++++++++++++++++++++++++
> drivers/gpu/drm/i915/gt/shmem_utils.h | 3 +++
> 2 files changed, 35 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/shmem_utils.c b/drivers/gpu/drm/i915/gt/shmem_utils.c
> index 0683b27a3890..402f085f3a02 100644
> --- a/drivers/gpu/drm/i915/gt/shmem_utils.c
> +++ b/drivers/gpu/drm/i915/gt/shmem_utils.c
> @@ -3,6 +3,7 @@
> * Copyright © 2020 Intel Corporation
> */
>
> +#include <linux/iosys-map.h>
> #include <linux/mm.h>
> #include <linux/pagemap.h>
> #include <linux/shmem_fs.h>
> @@ -123,6 +124,37 @@ static int __shmem_rw(struct file *file, loff_t off,
> return 0;
> }
>
> +int shmem_read_to_iosys_map(struct file *file, loff_t off,
> + struct iosys_map *map, size_t map_off, size_t len)
> +{
> + unsigned long pfn;
> +
> + for (pfn = off >> PAGE_SHIFT; len; pfn++) {
> + unsigned int this =
> + min_t(size_t, PAGE_SIZE - offset_in_page(off), len);
> + struct page *page;
> + void *vaddr;
> +
> + page = shmem_read_mapping_page_gfp(file->f_mapping, pfn,
> + GFP_KERNEL);
> + if (IS_ERR(page))
> + return PTR_ERR(page);
> +
> + vaddr = kmap(page);
> + iosys_map_memcpy_to(map, map_off, vaddr + offset_in_page(off),
> + this);
> + mark_page_accessed(page);
> + kunmap(page);
> + put_page(page);
> +
> + len -= this;
> + map_off += this;
> + off = 0;
> + }
> +
> + return 0;
> +}
> +
> int shmem_read(struct file *file, loff_t off, void *dst, size_t len)
> {
> return __shmem_rw(file, off, dst, len, false);
> diff --git a/drivers/gpu/drm/i915/gt/shmem_utils.h b/drivers/gpu/drm/i915/gt/shmem_utils.h
> index c1669170c351..b2b04d88c6e5 100644
> --- a/drivers/gpu/drm/i915/gt/shmem_utils.h
> +++ b/drivers/gpu/drm/i915/gt/shmem_utils.h
> @@ -8,6 +8,7 @@
>
> #include <linux/types.h>
>
> +struct iosys_map;
> struct drm_i915_gem_object;
> struct file;
>
> @@ -17,6 +18,8 @@ struct file *shmem_create_from_object(struct drm_i915_gem_object *obj);
> void *shmem_pin_map(struct file *file);
> void shmem_unpin_map(struct file *file, void *ptr);
>
> +int shmem_read_to_iosys_map(struct file *file, loff_t off,
> + struct iosys_map *map, size_t map_off, size_t len);
> int shmem_read(struct file *file, loff_t off, void *dst, size_t len);
> int shmem_write(struct file *file, loff_t off, void *src, size_t len);
>
> --
> 2.35.1
>
