diff options
| author | David Hildenbrand | 2022-11-16 11:26:52 +0100 |
|---|---|---|
| committer | Andrew Morton | 2022-11-30 15:58:59 -0800 |
| commit | 3298de2c66e0276abe6b95041fd3605a377523fc (patch) | |
| tree | 661f40740ea6a25ae51886429d8489cf60d7c9a4 | |
| parent | 129e636fe9837fcfea68bfd368a07548d9880726 (diff) | |
media: videobuf-dma-sg: remove FOLL_FORCE usage
GUP now supports reliable R/O long-term pinning in COW mappings, such
that we break COW early. MAP_SHARED VMAs only use the shared zeropage so
far in one corner case (DAXFS file with holes), which can be ignored
because GUP does not support long-term pinning in fsdax (see
check_vma_flags()).
Consequently, FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM is no longer required
for reliable R/O long-term pinning: FOLL_LONGTERM is sufficient. So stop
using FOLL_FORCE, which is really only for ptrace access.
Link: https://lkml.kernel.org/r/20221116102659.70287-14-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | drivers/media/v4l2-core/videobuf-dma-sg.c | 14 |
1 files changed, 5 insertions, 9 deletions
diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c index f75e5eedeee0..234e9f647c96 100644 --- a/drivers/media/v4l2-core/videobuf-dma-sg.c +++ b/drivers/media/v4l2-core/videobuf-dma-sg.c @@ -151,17 +151,16 @@ static void videobuf_dma_init(struct videobuf_dmabuf *dma) static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma, int direction, unsigned long data, unsigned long size) { + unsigned int gup_flags = FOLL_LONGTERM; unsigned long first, last; - int err, rw = 0; - unsigned int flags = FOLL_FORCE; + int err; dma->direction = direction; switch (dma->direction) { case DMA_FROM_DEVICE: - rw = READ; + gup_flags |= FOLL_WRITE; break; case DMA_TO_DEVICE: - rw = WRITE; break; default: BUG(); @@ -177,14 +176,11 @@ static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma, if (NULL == dma->pages) return -ENOMEM; - if (rw == READ) - flags |= FOLL_WRITE; - dprintk(1, "init user [0x%lx+0x%lx => %lu pages]\n", data, size, dma->nr_pages); - err = pin_user_pages(data & PAGE_MASK, dma->nr_pages, - flags | FOLL_LONGTERM, dma->pages, NULL); + err = pin_user_pages(data & PAGE_MASK, dma->nr_pages, gup_flags, + dma->pages, NULL); if (err != dma->nr_pages) { dma->nr_pages = (err >= 0) ? err : 0; |