Quite often it's a little hard to tell if reservations are already held
in code paths that unpin bo's. While our pinning/unpinning code should
be more explicit that requires a substential amount of work so instead
we can avoid the issues by making sure we try to reserve before unpinning.
Because we unpin those bo's only on destruction/error paths just that check
tells us if we're already reserved or not and allows to cleanly unpin.
Reviewed-by: Martin Krastev <krastevm@xxxxxxxxxx>
Reviewed-by: Roland Scheidegger <sroland@xxxxxxxxxx>
Fixes: d1a73c641afd ("drm/vmwgfx: Make sure we unpin no longer needed buffers")
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Zack Rusin <zackr@xxxxxxxxxx>
---
drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 11 +++++++++++
drivers/gpu/drm/vmwgfx/vmwgfx_mob.c | 18 ++++++++++++++----
2 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
index 8087a9013455..9a3133cb5cc1 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -1523,8 +1523,19 @@ static inline void vmw_bo_unreference(struct vmw_buffer_object **buf)
*buf = NULL;
if (tmp_buf != NULL) {
+ /*
+ * currently pinning requires a reservation to be held
+ * but unreference can be called either reserved or not.
+ * To avoid deadloacks we have to try to get a reservation.
+ * This is exlusively to satisfy the requirements of the
+ * unpin, ttm_bo_put will handle delayed deletion for us
+ * in case the bo is really busy.
+ */
+ bool locked = dma_resv_trylock(tmp_buf->base.base.resv);
if (tmp_buf->base.pin_count > 0)
ttm_bo_unpin(&tmp_buf->base);
+ if (locked)
+ dma_resv_unlock(tmp_buf->base.base.resv);
ttm_bo_put(&tmp_buf->base);
}
}
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c b/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c
index a0b53141dded..f2d625415458 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c
@@ -94,6 +94,16 @@ static void vmw_mob_pt_setup(struct vmw_mob *mob,
struct vmw_piter data_iter,
unsigned long num_data_pages);
+
+static inline void vmw_bo_unpin_unlocked(struct ttm_buffer_object *bo)
+{
+ int ret = ttm_bo_reserve(bo, false, true, NULL);
+ BUG_ON(ret != 0);
+ ttm_bo_unpin(bo);
+ ttm_bo_unreserve(bo);
+}
+
+
/*
* vmw_setup_otable_base - Issue an object table base setup command to
* the device
@@ -277,7 +287,7 @@ static int vmw_otable_batch_setup(struct vmw_private *dev_priv,
&batch->otables[i]);
}
- ttm_bo_unpin(batch->otable_bo);
+ vmw_bo_unpin_unlocked(batch->otable_bo);
ttm_bo_put(batch->otable_bo);
batch->otable_bo = NULL;
return ret;
@@ -341,9 +351,9 @@ static void vmw_otable_batch_takedown(struct vmw_private *dev_priv,
BUG_ON(ret != 0);
vmw_bo_fence_single(bo, NULL);
+ ttm_bo_unpin(bo);
ttm_bo_unreserve(bo);
- ttm_bo_unpin(batch->otable_bo);
ttm_bo_put(batch->otable_bo);
batch->otable_bo = NULL;
}
@@ -530,7 +540,7 @@ static void vmw_mob_pt_setup(struct vmw_mob *mob,
void vmw_mob_destroy(struct vmw_mob *mob)
{
if (mob->pt_bo) {
- ttm_bo_unpin(mob->pt_bo);
+ vmw_bo_unpin_unlocked(mob->pt_bo);
ttm_bo_put(mob->pt_bo);
mob->pt_bo = NULL;
}
@@ -646,7 +656,7 @@ int vmw_mob_bind(struct vmw_private *dev_priv,
out_no_cmd_space:
vmw_fifo_resource_dec(dev_priv);
if (pt_set_up) {
- ttm_bo_unpin(mob->pt_bo);
+ vmw_bo_unpin_unlocked(mob->pt_bo);
ttm_bo_put(mob->pt_bo);
mob->pt_bo = NULL;
}
--
2.27.0
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