Re: [PATCH v3 9/9] dma-buf: Remove internal lock

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Am 24.08.22 um 12:22 schrieb Dmitry Osipenko:
The internal dma-buf lock isn't needed anymore because the updated
locking specification claims that dma-buf reservation must be locked
by importers, and thus, the internal data is already protected by the
reservation lock. Remove the obsoleted internal lock.

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

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

---
  drivers/dma-buf/dma-buf.c | 14 ++++----------
  include/linux/dma-buf.h   |  9 ---------
  2 files changed, 4 insertions(+), 19 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 696d132b02f4..a0406254f0ae 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -656,7 +656,6 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
dmabuf->file = file; - mutex_init(&dmabuf->lock);
  	INIT_LIST_HEAD(&dmabuf->attachments);
mutex_lock(&db_list.lock);
@@ -1503,7 +1502,7 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_mmap_unlocked, DMA_BUF);
  int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
  {
  	struct iosys_map ptr;
-	int ret = 0;
+	int ret;
iosys_map_clear(map); @@ -1515,28 +1514,25 @@ int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
  	if (!dmabuf->ops->vmap)
  		return -EINVAL;
- mutex_lock(&dmabuf->lock);
  	if (dmabuf->vmapping_counter) {
  		dmabuf->vmapping_counter++;
  		BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
  		*map = dmabuf->vmap_ptr;
-		goto out_unlock;
+		return 0;
  	}
BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr)); ret = dmabuf->ops->vmap(dmabuf, &ptr);
  	if (WARN_ON_ONCE(ret))
-		goto out_unlock;
+		return ret;
dmabuf->vmap_ptr = ptr;
  	dmabuf->vmapping_counter = 1;
*map = dmabuf->vmap_ptr; -out_unlock:
-	mutex_unlock(&dmabuf->lock);
-	return ret;
+	return 0;
  }
  EXPORT_SYMBOL_NS_GPL(dma_buf_vmap, DMA_BUF);
@@ -1578,13 +1574,11 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
  	BUG_ON(dmabuf->vmapping_counter == 0);
  	BUG_ON(!iosys_map_is_equal(&dmabuf->vmap_ptr, map));
- mutex_lock(&dmabuf->lock);
  	if (--dmabuf->vmapping_counter == 0) {
  		if (dmabuf->ops->vunmap)
  			dmabuf->ops->vunmap(dmabuf, map);
  		iosys_map_clear(&dmabuf->vmap_ptr);
  	}
-	mutex_unlock(&dmabuf->lock);
  }
  EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap, DMA_BUF);
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index d48d534dc55c..aed6695bbb50 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -326,15 +326,6 @@ struct dma_buf {
  	/** @ops: dma_buf_ops associated with this buffer object. */
  	const struct dma_buf_ops *ops;
- /**
-	 * @lock:
-	 *
-	 * Used internally to serialize list manipulation, attach/detach and
-	 * vmap/unmap. Note that in many cases this is superseeded by
-	 * dma_resv_lock() on @resv.
-	 */
-	struct mutex lock;
-
  	/**
  	 * @vmapping_counter:
  	 *

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