[PATCH v1 4/6] dma-buf/heaps: Assert held reservation lock for dma-buf mmapping

[Dmitry Osipenko]

When userspace mmaps dma-buf's fd, the dma-buf reservation lock must be
held. Add locking sanity checks to the dma-buf mmaping callbacks to ensure
that the locking assumptions won't regress in the future.

Suggested-by: Daniel Vetter <dan...@ffwll.ch>
Signed-off-by: Dmitry Osipenko <dmitry.osipe...@collabora.com>
---
 drivers/dma-buf/heaps/cma_heap.c    | 3 +++
 drivers/dma-buf/heaps/system_heap.c | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
index 28fb04eccdd0..1131fb943992 100644
--- a/drivers/dma-buf/heaps/cma_heap.c
+++ b/drivers/dma-buf/heaps/cma_heap.c
@@ -13,6 +13,7 @@
 #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>
@@ -182,6 +183,8 @@ 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 fcf836ba9c1f..e8bd10e60998 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -13,6 +13,7 @@
 #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>
@@ -201,6 +202,8 @@ 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);
 
-- 
2.37.3