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    Subject[PATCH v3 2/6] dma-buf/heaps: Don't assert held reservation lock for dma-buf mmapping
    Date
    Don't assert held dma-buf reservation lock on memory mapping of exported
    buffer.

    We're going to change dma-buf mmap() locking policy such that exporters
    will have to handle the lock. The previous locking policy caused deadlock
    problem for DRM drivers in a case of self-imported dma-bufs once these
    drivers are moved to use reservation lock universally. The problem
    solved by moving the lock down to exporters. This patch prepares dma-buf
    heaps for the locking policy update.

    Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
    Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
    ---
    drivers/dma-buf/heaps/cma_heap.c | 3 ---
    drivers/dma-buf/heaps/system_heap.c | 3 ---
    2 files changed, 6 deletions(-)

    diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
    index a7f048048864..ee899f8e6721 100644
    --- a/drivers/dma-buf/heaps/cma_heap.c
    +++ b/drivers/dma-buf/heaps/cma_heap.c
    @@ -13,7 +13,6 @@
    #include <linux/dma-buf.h>
    #include <linux/dma-heap.h>
    #include <linux/dma-map-ops.h>
    -#include <linux/dma-resv.h>
    #include <linux/err.h>
    #include <linux/highmem.h>
    #include <linux/io.h>
    @@ -183,8 +182,6 @@ static int cma_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
    {
    struct cma_heap_buffer *buffer = dmabuf->priv;

    - dma_resv_assert_held(dmabuf->resv);
    -
    if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
    return -EINVAL;

    diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
    index ee7059399e9c..9076d47ed2ef 100644
    --- a/drivers/dma-buf/heaps/system_heap.c
    +++ b/drivers/dma-buf/heaps/system_heap.c
    @@ -13,7 +13,6 @@
    #include <linux/dma-buf.h>
    #include <linux/dma-mapping.h>
    #include <linux/dma-heap.h>
    -#include <linux/dma-resv.h>
    #include <linux/err.h>
    #include <linux/highmem.h>
    #include <linux/mm.h>
    @@ -201,8 +200,6 @@ static int system_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
    struct sg_page_iter piter;
    int ret;

    - dma_resv_assert_held(dmabuf->resv);
    -
    for_each_sgtable_page(table, &piter, vma->vm_pgoff) {
    struct page *page = sg_page_iter_page(&piter);

    --
    2.40.1
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