ivtv: convert get_user_pages() --> pin_user_pages()

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Walls <awalls@md.metrocast.net>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Link: http://lkml.kernel.org/r/20200518012157.1178336-3-jhubbard@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/media/pci/ivtv/ivtv-udma.c b/drivers/media/pci/ivtv/ivtv-udma.c
index 5f88830..0d8372c 100644 (file)
--- 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 cd2fe2d..5f7dc97 100644 (file)
--- 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 0c28598..e2d56dc 100644 (file)
--- 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;
        }