[PATCH v4 2/6] dma-buf/heaps: Don't assert held reservation lock for dma-buf mmapping

Dmitry Osipenko
2023-05-29T22:46:21Z

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 1131fb943992..28fb04eccdd0 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 e8bd10e60998..fcf836ba9c1f 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>
@@ -202,8 +201,6 @@ 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