Re: [PATCH v4 16/21] dma-buf: Move dma_buf_attach() to dynamic locking specification

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Am 31.08.22 um 17:37 schrieb Dmitry Osipenko:
Move dma-buf attachment API functions to the dynamic locking specification
by taking the reservation lock around the mapping operations. The strict
locking convention prevents deadlock situations for dma-buf importers and
exporters.

Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>

Reviewed-by: Christian König <christian.koenig@xxxxxxx>

---
  drivers/dma-buf/dma-buf.c | 20 ++++++++------------
  1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index ceea4839c641..073942bf5ae9 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -858,8 +858,8 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
  	    dma_buf_is_dynamic(dmabuf)) {
  		struct sg_table *sgt;
+ dma_resv_lock(attach->dmabuf->resv, NULL);
  		if (dma_buf_is_dynamic(attach->dmabuf)) {
-			dma_resv_lock(attach->dmabuf->resv, NULL);
  			ret = dmabuf->ops->pin(attach);
  			if (ret)
  				goto err_unlock;
@@ -872,8 +872,7 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
  			ret = PTR_ERR(sgt);
  			goto err_unpin;
  		}
-		if (dma_buf_is_dynamic(attach->dmabuf))
-			dma_resv_unlock(attach->dmabuf->resv);
+		dma_resv_unlock(attach->dmabuf->resv);
  		attach->sgt = sgt;
  		attach->dir = DMA_BIDIRECTIONAL;
  	}
@@ -889,8 +888,7 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
  		dmabuf->ops->unpin(attach);
err_unlock:
-	if (dma_buf_is_dynamic(attach->dmabuf))
-		dma_resv_unlock(attach->dmabuf->resv);
+	dma_resv_unlock(attach->dmabuf->resv);
dma_buf_detach(dmabuf, attach);
  	return ERR_PTR(ret);
@@ -936,21 +934,19 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
  	if (WARN_ON(!dmabuf || !attach))
  		return;
+ dma_resv_lock(attach->dmabuf->resv, NULL);
+
  	if (attach->sgt) {
-		if (dma_buf_is_dynamic(attach->dmabuf))
-			dma_resv_lock(attach->dmabuf->resv, NULL);
__unmap_dma_buf(attach, attach->sgt, attach->dir); - if (dma_buf_is_dynamic(attach->dmabuf)) {
+		if (dma_buf_is_dynamic(attach->dmabuf))
  			dmabuf->ops->unpin(attach);
-			dma_resv_unlock(attach->dmabuf->resv);
-		}
  	}
-
-	dma_resv_lock(dmabuf->resv, NULL);
  	list_del(&attach->node);
+
  	dma_resv_unlock(dmabuf->resv);
+
  	if (dmabuf->ops->detach)
  		dmabuf->ops->detach(dmabuf, attach);




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