lkml.org 
[lkml]   [2020]   [May]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v2 03/21] drm: armada: fix sg_table nents vs. orig_nents misuse
    Date
    The Documentation/DMA-API-HOWTO.txt states that dma_map_sg returns the
    numer of the created entries in the DMA address space. However the
    subsequent calls to dma_sync_sg_for_{device,cpu} and dma_unmap_sg must be
    called with the original number of entries passed to dma_map_sg. The
    sg_table->nents in turn holds the result of the dma_map_sg call as stated
    in include/linux/scatterlist.h. Adapt the code to obey those rules.

    Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
    ---
    For more information, see '[PATCH v2 00/21] DRM: fix struct sg_table nents
    vs. orig_nents misuse' thread: https://lkml.org/lkml/2020/5/4/373
    ---
    drivers/gpu/drm/armada/armada_gem.c | 14 +++++++++-----
    1 file changed, 9 insertions(+), 5 deletions(-)

    diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada/armada_gem.c
    index 976685f..749647f 100644
    --- a/drivers/gpu/drm/armada/armada_gem.c
    +++ b/drivers/gpu/drm/armada/armada_gem.c
    @@ -407,8 +407,10 @@ int armada_gem_pwrite_ioctl(struct drm_device *dev, void *data,
    sg_set_page(sg, page, PAGE_SIZE, 0);
    }

    - if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0) {
    - num = sgt->nents;
    + sgt->nents = dma_map_sg(attach->dev, sgt->sgl, sgt->orig_nents,
    + dir);
    + if (sgt->nents == 0) {
    + num = sgt->orig_nents;
    goto release;
    }
    } else if (dobj->page) {
    @@ -418,7 +420,9 @@ int armada_gem_pwrite_ioctl(struct drm_device *dev, void *data,

    sg_set_page(sgt->sgl, dobj->page, dobj->obj.size, 0);

    - if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0)
    + sgt->nents = dma_map_sg(attach->dev, sgt->sgl, sgt->orig_nents,
    + dir);
    + if (sgt->nents == 0)
    goto free_table;
    } else if (dobj->linear) {
    /* Single contiguous physical region - no struct page */
    @@ -449,11 +453,11 @@ static void armada_gem_prime_unmap_dma_buf(struct dma_buf_attachment *attach,
    int i;

    if (!dobj->linear)
    - dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
    + dma_unmap_sg(attach->dev, sgt->sgl, sgt->orig_nents, dir);

    if (dobj->obj.filp) {
    struct scatterlist *sg;
    - for_each_sg(sgt->sgl, sg, sgt->nents, i)
    + for_each_sg(sgt->sgl, sg, sgt->orig_nents, i)
    put_page(sg_page(sg));
    }

    --
    1.9.1
    \
     
     \ /
      Last update: 2020-05-04 14:56    [W:2.626 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site