drm/ttm: alter cpu_writers to return -EBUSY in ttm_execbuf_util reservations

This is similar to other platforms that don't allow command submission
to buffers locked on the cpu.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 5f61f133b4193a0f0bbea747dd32f599dc66fb7e..7426fe59108e65485b5bd45f5c2aa1c462518b63 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1053,16 +1053,6 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 }
 EXPORT_SYMBOL(ttm_bo_mem_space);
 
-int ttm_bo_wait_cpu(struct ttm_buffer_object *bo, bool no_wait)
-{
-       if ((atomic_read(&bo->cpu_writers) > 0) && no_wait)
-               return -EBUSY;
-
-       return wait_event_interruptible(bo->event_queue,
-                                       atomic_read(&bo->cpu_writers) == 0);
-}
-EXPORT_SYMBOL(ttm_bo_wait_cpu);
-
 int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
                        struct ttm_placement *placement,
                        bool interruptible, bool no_wait_reserve,
@@ -1788,8 +1778,7 @@ EXPORT_SYMBOL(ttm_bo_synccpu_write_grab);
 
 void ttm_bo_synccpu_write_release(struct ttm_buffer_object *bo)
 {
-       if (atomic_dec_and_test(&bo->cpu_writers))
-               wake_up_all(&bo->event_queue);
+       atomic_dec(&bo->cpu_writers);
 }
 EXPORT_SYMBOL(ttm_bo_synccpu_write_release);
 

diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
index b227a9961a07b97d3bbcfd094d6db280d212baa5..1986d006c2641750fa1b4202a5d200fbf6df898f 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
+++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
@@ -185,10 +185,7 @@ retry_this_bo:
                        ttm_eu_backoff_reservation_locked(list);
                        spin_unlock(&glob->lru_lock);
                        ttm_eu_list_ref_sub(list);
-                       ret = ttm_bo_wait_cpu(bo, false);
-                       if (ret)
-                               return ret;
-                       goto retry;
+                       return -EBUSY;
                }
        }
 

diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 5ff938df5fce762406d770013235e641c974965f..c6cae733ddefcf3ade54fbc3a647a9b2a80582d9 100644 (file)
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -424,8 +424,9 @@ extern void ttm_bo_unlock_delayed_workqueue(struct ttm_bo_device *bdev,
  * @no_wait: Return immediately if buffer is busy.
  *
  * Synchronizes a buffer object for CPU RW access. This means
- * blocking command submission that affects the buffer and
- * waiting for buffer idle. This lock is recursive.
+ * command submission that affects the buffer will return -EBUSY
+ * until ttm_bo_synccpu_write_release is called.
+ *
  * Returns
  * -EBUSY if the buffer is busy and no_wait is true.
  * -ERESTARTSYS if interrupted by a signal.

diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index 4789beee3b770783c68d5f8252bc96e45d60e6f2..dd96442cdc2a4d3ba64f2467037fd8518928054d 100644 (file)
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -726,20 +726,6 @@ extern void ttm_bo_mem_put(struct ttm_buffer_object *bo,
 extern void ttm_bo_mem_put_locked(struct ttm_buffer_object *bo,
                                  struct ttm_mem_reg *mem);
 
-/**
- * ttm_bo_wait_for_cpu
- *
- * @bo: Pointer to a struct ttm_buffer_object.
- * @no_wait: Don't sleep while waiting.
- *
- * Wait until a buffer object is no longer sync'ed for CPU access.
- * Returns:
- * -EBUSY: Buffer object was sync'ed for CPU access. (only if no_wait == 1).
- * -ERESTARTSYS: An interruptible sleep was interrupted by a signal.
- */
-
-extern int ttm_bo_wait_cpu(struct ttm_buffer_object *bo, bool no_wait);
-
 extern void ttm_bo_global_release(struct drm_global_reference *ref);
 extern int ttm_bo_global_init(struct drm_global_reference *ref);