Am 23.05.2018 um 15:13 schrieb Qiang Yu:
On Wed, May 23, 2018 at 5:35 PM, Christian König
<ckoenig.leichtzumerken@xxxxxxxxx> wrote:
Well NAK, that brings back a callback we worked quite hard on getting rid
of.
It looks like the problem isn't that you need the preclose callback, but you
rather seem to misunderstood how TTM works.
All you need to do is to cleanup your command submission path so that the
caller of lima_sched_context_queue_task() adds the resulting scheduler fence
to TTMs buffer objects.
You mean adding the finished dma fence to the buffer's reservation object then
waiting it before unmap the buffer from GPU VM in the drm_release()'s buffer
close callback?
That is one possibility, but also not necessary.
TTM has a destroy callback which is called from a workqueue when all
fences on that BOs have signaled.
Depending on your VM management you can use it to delay unmapping the
buffer until it is actually not used any more.
Adding fence is done already, and I did wait it before unmap. But then
I see when
the buffer is shared between processes, the "perfect wait" is just
wait the fence
from this process's task, so it's better to also distinguish fences.
If so, I just think
why we don't just wait tasks from this process in the preclose before unmap/free
buffer in the drm_release()?
Well it depends on your VM management. When userspace expects that the
VM space the BO used is reusable immediately than the TTM callback won't
work.
On the other hand you can just grab the list of fences on a BO and
filter out the ones from your current process and wait for those. See
amdgpu_sync_resv() as an example how to do that.
Christian.
Regards,
Qiang
Am 18.05.2018 um 11:27 schrieb Qiang Yu:
This reverts commit 45c3d213a400c952ab7119f394c5293bb6877e6b.
lima driver need preclose to wait all task in the context
created within closing file to finish before free all the
buffer object. Otherwise pending tesk may fail and get
noisy MMU fault message.
Move this wait to each buffer object free function can
achieve the same result but some buffer object is shared
with other file context, but we only want to wait the
closing file context's tasks. So the implementation is
not that straight forword compared to the preclose one.
Signed-off-by: Qiang Yu <yuq825@xxxxxxxxx>
---
drivers/gpu/drm/drm_file.c | 8 ++++----
include/drm/drm_drv.h | 23 +++++++++++++++++++++--
2 files changed, 25 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index e394799979a6..0a43107396b9 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -361,8 +361,9 @@ void drm_lastclose(struct drm_device * dev)
*
* This function must be used by drivers as their
&file_operations.release
* method. It frees any resources associated with the open file, and
calls the
- * &drm_driver.postclose driver callback. If this is the last open file
for the
- * DRM device also proceeds to call the &drm_driver.lastclose driver
callback.
+ * &drm_driver.preclose and &drm_driver.lastclose driver callbacks. If
this is
+ * the last open file for the DRM device also proceeds to call the
+ * &drm_driver.lastclose driver callback.
*
* RETURNS:
*
@@ -382,8 +383,7 @@ int drm_release(struct inode *inode, struct file
*filp)
list_del(&file_priv->lhead);
mutex_unlock(&dev->filelist_mutex);
- if (drm_core_check_feature(dev, DRIVER_LEGACY) &&
- dev->driver->preclose)
+ if (dev->driver->preclose)
dev->driver->preclose(dev, file_priv);
/* ========================================================
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index d23dcdd1bd95..8d6080f97ed4 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -107,6 +107,23 @@ struct drm_driver {
*/
int (*open) (struct drm_device *, struct drm_file *);
+ /**
+ * @preclose:
+ *
+ * One of the driver callbacks when a new &struct drm_file is
closed.
+ * Useful for tearing down driver-private data structures
allocated in
+ * @open like buffer allocators, execution contexts or similar
things.
+ *
+ * Since the display/modeset side of DRM can only be owned by
exactly
+ * one &struct drm_file (see &drm_file.is_master and
&drm_device.master)
+ * there should never be a need to tear down any modeset related
+ * resources in this callback. Doing so would be a driver design
bug.
+ *
+ * FIXME: It is not really clear why there's both @preclose and
+ * @postclose. Without a really good reason, use @postclose only.
+ */
+ void (*preclose) (struct drm_device *, struct drm_file
*file_priv);
+
/**
* @postclose:
*
@@ -118,6 +135,9 @@ struct drm_driver {
* one &struct drm_file (see &drm_file.is_master and
&drm_device.master)
* there should never be a need to tear down any modeset related
* resources in this callback. Doing so would be a driver design
bug.
+ *
+ * FIXME: It is not really clear why there's both @preclose and
+ * @postclose. Without a really good reason, use @postclose only.
*/
void (*postclose) (struct drm_device *, struct drm_file *);
@@ -134,7 +154,7 @@ struct drm_driver {
* state changes, e.g. in conjunction with the
:ref:`vga_switcheroo`
* infrastructure.
*
- * This is called after @postclose hook has been called.
+ * This is called after @preclose and @postclose have been called.
*
* NOTE:
*
@@ -601,7 +621,6 @@ struct drm_driver {
/* List of devices hanging off this driver with stealth attach. */
struct list_head legacy_dev_list;
int (*firstopen) (struct drm_device *);
- void (*preclose) (struct drm_device *, struct drm_file
*file_priv);
int (*dma_ioctl) (struct drm_device *dev, void *data, struct
drm_file *file_priv);
int (*dma_quiescent) (struct drm_device *);
int (*context_dtor) (struct drm_device *dev, int context);
--
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