[PATCH] dma-buf: Use dma_fence_unwrap_for_each when importing fences

[Jason Ekstrand]

Ever since 68129f431faa ("dma-buf: warn about containers in dma_resv object"),
dma_resv_add_shared_fence will warn if you attempt to add a container fence.
While most drivers were fine, fences can also be added to a dma_resv via the
recently added DMA_BUF_IOCTL_IMPORT_SYNC_FILE.  Use dma_fence_unwrap_for_each
to add each fence one at a time.

Fixes: 594740497e99 ("dma-buf: Add an API for importing sync files (v10)")
Signed-off-by: Jason Ekstrand <jason.ekstr...@collabora.com>
Reported-by: Sarah Walker <sarah.wal...@imgtec.com>
Cc: Christian König <christian.koe...@amd.com>
---
 drivers/dma-buf/dma-buf.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 630133284e2b..8d5d45112f52 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -15,6 +15,7 @@
 #include <linux/slab.h>
 #include <linux/dma-buf.h>
 #include <linux/dma-fence.h>
+#include <linux/dma-fence-unwrap.h>
 #include <linux/anon_inodes.h>
 #include <linux/export.h>
 #include <linux/debugfs.h>
@@ -391,8 +392,10 @@ static long dma_buf_import_sync_file(struct dma_buf 
*dmabuf,
                                     const void __user *user_data)
 {
        struct dma_buf_import_sync_file arg;
-       struct dma_fence *fence;
+       struct dma_fence *fence, *f;
        enum dma_resv_usage usage;
+       struct dma_fence_unwrap iter;
+       unsigned int num_fences;
        int ret = 0;
 
        if (copy_from_user(&arg, user_data, sizeof(arg)))
@@ -411,13 +414,21 @@ static long dma_buf_import_sync_file(struct dma_buf 
*dmabuf,
        usage = (arg.flags & DMA_BUF_SYNC_WRITE) ? DMA_RESV_USAGE_WRITE :
                                                   DMA_RESV_USAGE_READ;
 
-       dma_resv_lock(dmabuf->resv, NULL);
+       num_fences = 0;
+       dma_fence_unwrap_for_each(f, &iter, fence)
+               ++num_fences;
 
-       ret = dma_resv_reserve_fences(dmabuf->resv, 1);
-       if (!ret)
-               dma_resv_add_fence(dmabuf->resv, fence, usage);
+       if (num_fences > 0) {
+               dma_resv_lock(dmabuf->resv, NULL);
 
-       dma_resv_unlock(dmabuf->resv);
+               ret = dma_resv_reserve_fences(dmabuf->resv, num_fences);
+               if (!ret) {
+                       dma_fence_unwrap_for_each(f, &iter, fence)
+                               dma_resv_add_fence(dmabuf->resv, f, usage);
+               }
+
+               dma_resv_unlock(dmabuf->resv);
+       }
 
        dma_fence_put(fence);
 
-- 
2.36.1