[PATCH v2] drm/etnaviv: convert get_user_pages() --> pin_user_pages()

From: John Hubbard
Date: Mon May 25 2020 - 19:49:50 EST


This code was using get_user_pages*(), in a "Case 2" scenario
(DMA/RDMA), using the categorization from [1]. That means that it's
time to convert the get_user_pages*() + put_page() calls to
pin_user_pages*() + unpin_user_pages() calls.

There is some helpful background in [2]: basically, this is a small
part of fixing a long-standing disconnect between pinning pages, and
file systems' use of those pages.

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
https://lwn.net/Articles/807108/

Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---

Hi,

Changes since v1:

* Rebased onto Linux 5.7-rc7

* Added: Lucas Stach

thanks
John Hubbard
NVIDIA


drivers/gpu/drm/etnaviv/etnaviv_gem.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index dc9ef302f517..0f4578dc169d 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -675,10 +675,10 @@ static int etnaviv_gem_userptr_get_pages(struct etnaviv_gem_object *etnaviv_obj)
uint64_t ptr = userptr->ptr + pinned * PAGE_SIZE;
struct page **pages = pvec + pinned;

- ret = get_user_pages_fast(ptr, num_pages,
+ ret = pin_user_pages_fast(ptr, num_pages,
!userptr->ro ? FOLL_WRITE : 0, pages);
if (ret < 0) {
- release_pages(pvec, pinned);
+ unpin_user_pages(pvec, pinned);
kvfree(pvec);
return ret;
}
@@ -702,7 +702,7 @@ static void etnaviv_gem_userptr_release(struct etnaviv_gem_object *etnaviv_obj)
if (etnaviv_obj->pages) {
int npages = etnaviv_obj->base.size >> PAGE_SHIFT;

- release_pages(etnaviv_obj->pages, npages);
+ unpin_user_pages(etnaviv_obj->pages, npages);
kvfree(etnaviv_obj->pages);
}
}
--
2.26.2