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

Dmitry Osipenko
2022-11-10T20:15:12Z

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 <daniel@ffwll.ch>
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 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