On Thu, Apr 18, 2019 at 08:28:51AM +0000, Koenig, Christian wrote:
Am 18.04.19 um 10:08 schrieb Daniel Vetter:
On Wed, Apr 17, 2019 at 09:13:22PM +0200, Christian König wrote:
Am 17.04.19 um 21:07 schrieb Daniel Vetter:
On Tue, Apr 16, 2019 at 08:38:33PM +0200, Christian König wrote:
Each importer can now provide an invalidate_mappings callback.
This allows the exporter to provide the mappings without the need to pin the backing store.
v2: don't try to invalidate mappings when the callback is NULL, lock the reservation obj while using the attachments, add helper to set the callback v3: move flag for invalidation support into the DMA-buf, use new attach_info structure to set the callback v4: use importer_priv field instead of mangling exporter priv. v5: drop invalidation_supported flag
Signed-off-by: Christian König christian.koenig@amd.com
drivers/dma-buf/dma-buf.c | 37 +++++++++++++++++++++++++++++++++++++ include/linux/dma-buf.h | 33 +++++++++++++++++++++++++++++++-- 2 files changed, 68 insertions(+), 2 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 83c92bfd964c..a3738fab3927 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -563,6 +563,8 @@ struct dma_buf_attachment *dma_buf_attach(const struct dma_buf_attach_info *info attach->dev = info->dev; attach->dmabuf = dmabuf;
- attach->importer_priv = info->importer_priv;
- attach->invalidate = info->invalidate; mutex_lock(&dmabuf->lock);
@@ -571,7 +573,9 @@ struct dma_buf_attachment *dma_buf_attach(const struct dma_buf_attach_info *info if (ret) goto err_attach; }
- reservation_object_lock(dmabuf->resv, NULL); list_add(&attach->node, &dmabuf->attachments);
- reservation_object_unlock(dmabuf->resv); mutex_unlock(&dmabuf->lock);
@@ -615,7 +619,9 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) DMA_BIDIRECTIONAL); mutex_lock(&dmabuf->lock);
- reservation_object_lock(dmabuf->resv, NULL); list_del(&attach->node);
- reservation_object_unlock(dmabuf->resv); if (dmabuf->ops->detach) dmabuf->ops->detach(dmabuf, attach);
@@ -653,7 +659,16 @@ dma_buf_map_attachment_locked(struct dma_buf_attachment *attach, if (attach->sgt) return attach->sgt;
- /*
* Mapping a DMA-buf can trigger its invalidation, prevent sending this* event to the caller by temporary removing this attachment from the* list.*/- if (attach->invalidate)
list_del(&attach->node);Just noticed this: Why do we need this? invalidate needs the reservation lock, as does map_attachment. It should be impssoble to have someone else sneak in here.
I was having problems with self triggered invalidations.
E.g. client A tries to map an attachment, that in turn causes the buffer to move to a new place and client A is informed about that movement with an invalidation.
Uh, that sounds like a bug in ttm or somewhere else in the exporter. If you evict the bo that you're trying to map, that's bad.
Or maybe it's a framework bug, and we need to track whether an attachment has a map or not. That would make more sense ...
Well neither, as far as I can see this is perfectly normal behavior.
We just don't want any invalidation send to a driver which is currently making a mapping.
If you want I can do this in the driver as well, but at least of hand it looks like a good idea to have that in common code.
Hm. This sounds like we'd want to invalidate a specific mapping.
Tracking the mappings could work as well, but the problem here is that I actually want the lifetime of old and new mappings to overlap for pipelining.
Aside: Overlapping mappings being explicitly allowed should be in the docs. The current kerneldoc for invalidate leaves that up for interpretation. This answers one of the questions I had overnight, about whether we expect ->invalidate to tear down the mapping or not.
Imo a better semantics would be that ->invalidate must tear down the mapping, but the exporter must delay actual unmap until all fences have cleared. Otherwise you could end up with fun stuff where the exporter releases the memory (it wanted to invalidate after all), while the importer still has a mapping around. That's not going to end well I think.
That would also solve the issue of getting an invalidate while you map, at least if we filter per attachment. -Daniel