From: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Date: Mon, 29 May 2023 22:39:31 +0000 (+0300)
Subject: dma-buf/heaps: Don't assert held reservation lock for dma-buf mmapping
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=30b5144ca41266ffc6071c33eea4076b66ac5eb9;p=linux.git

dma-buf/heaps: Don't assert held reservation lock for dma-buf mmapping

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>
Link: https://patchwork.freedesktop.org/patch/msgid/20230529223935.2672495-3-dmitry.osipenko@collabora.com
---

diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
index a7f048048864a..ee899f8e67215 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 ee7059399e9c7..9076d47ed2ef4 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);