On Fri, Jun 01, 2018 at 02:00:18PM +0200, Christian König wrote:
First step towards unpinned DMA buf operation.
I've checked the DRM drivers to potential locking of the reservation object, but essentially we need to audit all implementations of the dma_buf _ops for this to work.
Signed-off-by: Christian König christian.koenig@amd.com
Agreed in principle, but I expect a fireworks show with just this patch applied. It's not just that we need to audit all the implementations of dma-buf-ops, we also need to audit all the callers.
No idea yet how to go about merging this, but for a start might be good to throw this at the intel-gfx CI (just Cc: the intel-gfx mailing lists, but make sure your series applies without amd-staging-next stuff which isn't in drm.git yet). -Daniel
drivers/dma-buf/dma-buf.c | 4 ++++ include/linux/dma-buf.h | 4 ++++ 2 files changed, 8 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index e4c657d9fad7..4f0708cb58a7 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -631,7 +631,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, if (WARN_ON(!attach || !attach->dmabuf)) return ERR_PTR(-EINVAL);
- reservation_object_lock(attach->dmabuf->resv, NULL); sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
- reservation_object_unlock(attach->dmabuf->resv); if (!sg_table) sg_table = ERR_PTR(-ENOMEM);
@@ -658,8 +660,10 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, if (WARN_ON(!attach || !attach->dmabuf || !sg_table)) return;
- reservation_object_lock(attach->dmabuf->resv, NULL); attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
- reservation_object_unlock(attach->dmabuf->resv);
} EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index d17cadd76802..d2ba7a027a78 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -118,6 +118,8 @@ struct dma_buf_ops { * any other kind of sharing that the exporter might wish to make * available to buffer-users. *
* This is called with the dmabuf->resv object locked.*
- Returns:
- A &sg_table scatter list of or the backing storage of the DMA buffer,
@@ -138,6 +140,8 @@ struct dma_buf_ops { * It should also unpin the backing storage if this is the last mapping * of the DMA buffer, it the exporter supports backing storage * migration.
** This is called with the dmabuf->resv object locked.-- 2.14.1
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