Make use of the FAULT_FLAG_ALLOW_RETRY flag to allow dropping the
mmap_sem while waiting for bo idle.
FAULT_FLAG_ALLOW_RETRY appears to be primarily designed for disk waits
but should work just as fine for GPU waits..
Only compile-tested so far pending comments.
Signed-off-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 61 ++++++++++++++++++++++++++++++---------
1 file changed, 48 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 1006c15..6510ce2 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -41,6 +41,50 @@
#define TTM_BO_VM_NUM_PREFAULT 16
+static int ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
+ struct vm_area_struct *vma,
+ struct vm_fault *vmf)
+{
+ struct ttm_bo_device *bdev = bo->bdev;
+ int ret = 0;
+
+ spin_lock(&bdev->fence_lock);
+ if (likely(!test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)))
+ goto out_unlock;
+
+ /*
+ * Quick non-stalling check for idle.
+ */
+ ret = ttm_bo_wait(bo, false, false, true);
+ if (likely(ret == 0))
+ goto out_unlock;
+
+ /*
+ * If possible, avoid waiting for GPU with mmap_sem
+ * held.
+ */
+ if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) {
+ ret = VM_FAULT_RETRY;
+ if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
+ goto out_unlock;
+
+ up_read(&vma->vm_mm->mmap_sem);
+ (void) ttm_bo_wait(bo, false, true, false);
+ goto out_unlock;
+ }
+
+ /*
+ * Ordinary wait.
+ */
+ ret = ttm_bo_wait(bo, false, true, false);
+ if (unlikely(ret != 0))
+ ret = (ret == -ERESTARTSYS) ? VM_FAULT_SIGBUS :
+ VM_FAULT_NOPAGE;
+out_unlock:
+ spin_unlock(&bdev->fence_lock);
+ return ret;
+}
+
static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct ttm_buffer_object *bo = (struct ttm_buffer_object *)
@@ -91,19 +135,10 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
* Wait for buffer data in transit, due to a pipelined
* move.
*/
-
- spin_lock(&bdev->fence_lock);
- if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) {
- ret = ttm_bo_wait(bo, false, true, false);
- spin_unlock(&bdev->fence_lock);
- if (unlikely(ret != 0)) {
- retval = (ret != -ERESTARTSYS) ?
- VM_FAULT_SIGBUS : VM_FAULT_NOPAGE;
- goto out_unlock;
- }
- } else
- spin_unlock(&bdev->fence_lock);
-
+ retval = ttm_bo_vm_fault_idle(bo, vma, vmf);
+ if (unlikely(retval != 0))
+ goto out_unlock;
+
ret = ttm_mem_io_lock(man, true);
if (unlikely(ret != 0)) {
retval = VM_FAULT_NOPAGE;
--
1.7.10.4
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