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Subject[PATCH v2 2/2] ivtv: convert get_user_pages() --> pin_user_pages()
Date
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@nvidia.com>
---
drivers/media/pci/ivtv/ivtv-udma.c | 19 ++++++-------------
drivers/media/pci/ivtv/ivtv-yuv.c | 17 ++++++-----------
drivers/media/pci/ivtv/ivtvfb.c | 4 ++--
3 files changed, 14 insertions(+), 26 deletions(-)

diff --git a/drivers/media/pci/ivtv/ivtv-udma.c b/drivers/media/pci/ivtv/ivtv-udma.c
index 5f8883031c9c..0d8372cc364a 100644
--- a/drivers/media/pci/ivtv/ivtv-udma.c
+++ b/drivers/media/pci/ivtv/ivtv-udma.c
@@ -92,7 +92,7 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
{
struct ivtv_dma_page_info user_dma;
struct ivtv_user_dma *dma = &itv->udma;
- int i, err;
+ int err;

IVTV_DEBUG_DMA("ivtv_udma_setup, dst: 0x%08x\n", (unsigned int)ivtv_dest_addr);

@@ -111,16 +111,15 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
return -EINVAL;
}

- /* Get user pages for DMA Xfer */
- err = get_user_pages_unlocked(user_dma.uaddr, user_dma.page_count,
+ /* Pin user pages for DMA Xfer */
+ err = pin_user_pages_unlocked(user_dma.uaddr, user_dma.page_count,
dma->map, FOLL_FORCE);

if (user_dma.page_count != err) {
IVTV_DEBUG_WARN("failed to map user pages, returned %d instead of %d\n",
err, user_dma.page_count);
if (err >= 0) {
- for (i = 0; i < err; i++)
- put_page(dma->map[i]);
+ unpin_user_pages(dma->map, err);
return -EINVAL;
}
return err;
@@ -130,9 +129,7 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,

/* Fill SG List with new values */
if (ivtv_udma_fill_sg_list(dma, &user_dma, 0) < 0) {
- for (i = 0; i < dma->page_count; i++) {
- put_page(dma->map[i]);
- }
+ unpin_user_pages(dma->map, dma->page_count);
dma->page_count = 0;
return -ENOMEM;
}
@@ -153,7 +150,6 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
void ivtv_udma_unmap(struct ivtv *itv)
{
struct ivtv_user_dma *dma = &itv->udma;
- int i;

IVTV_DEBUG_INFO("ivtv_unmap_user_dma\n");

@@ -169,10 +165,7 @@ void ivtv_udma_unmap(struct ivtv *itv)
/* sync DMA */
ivtv_udma_sync_for_cpu(itv);

- /* Release User Pages */
- for (i = 0; i < dma->page_count; i++) {
- put_page(dma->map[i]);
- }
+ unpin_user_pages(dma->map, dma->page_count);
dma->page_count = 0;
}

diff --git a/drivers/media/pci/ivtv/ivtv-yuv.c b/drivers/media/pci/ivtv/ivtv-yuv.c
index cd2fe2d444c0..5f7dc9771f8d 100644
--- a/drivers/media/pci/ivtv/ivtv-yuv.c
+++ b/drivers/media/pci/ivtv/ivtv-yuv.c
@@ -30,7 +30,6 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
struct yuv_playback_info *yi = &itv->yuv_info;
u8 frame = yi->draw_frame;
struct yuv_frame_info *f = &yi->new_frame_info[frame];
- int i;
int y_pages, uv_pages;
unsigned long y_buffer_offset, uv_buffer_offset;
int y_decode_height, uv_decode_height, y_size;
@@ -62,12 +61,12 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
ivtv_udma_get_page_info (&y_dma, (unsigned long)args->y_source, 720 * y_decode_height);
ivtv_udma_get_page_info (&uv_dma, (unsigned long)args->uv_source, 360 * uv_decode_height);

- /* Get user pages for DMA Xfer */
- y_pages = get_user_pages_unlocked(y_dma.uaddr,
+ /* Pin user pages for DMA Xfer */
+ y_pages = pin_user_pages_unlocked(y_dma.uaddr,
y_dma.page_count, &dma->map[0], FOLL_FORCE);
uv_pages = 0; /* silence gcc. value is set and consumed only if: */
if (y_pages == y_dma.page_count) {
- uv_pages = get_user_pages_unlocked(uv_dma.uaddr,
+ uv_pages = pin_user_pages_unlocked(uv_dma.uaddr,
uv_dma.page_count, &dma->map[y_pages],
FOLL_FORCE);
}
@@ -81,8 +80,7 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
uv_pages, uv_dma.page_count);

if (uv_pages >= 0) {
- for (i = 0; i < uv_pages; i++)
- put_page(dma->map[y_pages + i]);
+ unpin_user_pages(&dma->map[y_pages], uv_pages);
rc = -EFAULT;
} else {
rc = uv_pages;
@@ -93,8 +91,7 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
y_pages, y_dma.page_count);
}
if (y_pages >= 0) {
- for (i = 0; i < y_pages; i++)
- put_page(dma->map[i]);
+ unpin_user_pages(dma->map, y_pages);
/*
* Inherit the -EFAULT from rc's
* initialization, but allow it to be
@@ -112,9 +109,7 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
/* Fill & map SG List */
if (ivtv_udma_fill_sg_list (dma, &uv_dma, ivtv_udma_fill_sg_list (dma, &y_dma, 0)) < 0) {
IVTV_DEBUG_WARN("could not allocate bounce buffers for highmem userspace buffers\n");
- for (i = 0; i < dma->page_count; i++) {
- put_page(dma->map[i]);
- }
+ unpin_user_pages(dma->map, dma->page_count);
dma->page_count = 0;
return -ENOMEM;
}
diff --git a/drivers/media/pci/ivtv/ivtvfb.c b/drivers/media/pci/ivtv/ivtvfb.c
index 0c2859844081..e2d56dca5be4 100644
--- a/drivers/media/pci/ivtv/ivtvfb.c
+++ b/drivers/media/pci/ivtv/ivtvfb.c
@@ -281,10 +281,10 @@ static int ivtvfb_prep_dec_dma_to_device(struct ivtv *itv,
/* Map User DMA */
if (ivtv_udma_setup(itv, ivtv_dest_addr, userbuf, size_in_bytes) <= 0) {
mutex_unlock(&itv->udma.lock);
- IVTVFB_WARN("ivtvfb_prep_dec_dma_to_device, Error with get_user_pages: %d bytes, %d pages returned\n",
+ IVTVFB_WARN("ivtvfb_prep_dec_dma_to_device, Error with pin_user_pages: %d bytes, %d pages returned\n",
size_in_bytes, itv->udma.page_count);

- /* get_user_pages must have failed completely */
+ /* pin_user_pages must have failed completely */
return -EIO;
}

--
2.26.2
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