[Linaro-mm-sig] Re: [PATCH v4 21/21] dma-buf: Remove obsoleted internal lock

Am 31.08.22 um 17:37 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.

Acked-by: Christian König christian.koenig@amd.com Signed-off-by: Dmitry Osipenko dmitry.osipenko@collabora.com

Reviewed-by: Christian König christian.koenig@amd.com

---

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 97ce884fad76..772fdd9eeed8 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); @@ -1502,7 +1501,7 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, 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); @@ -1514,28 +1513,25 @@ 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);

@@ -1577,13 +1573,11 @@ 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 f11b5bbc2f37..6fa8d4e29719 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: