[RFC PATCH v1 2/5] drm/gpusvm: move dma_addr allocation before the notifier lock

[Honglei Huang <honghuan@amd.com>]

The dma_addr allocation was in a lazy allocation flow, it needs unlock
and goto map_pages. The allocation only needs npages, so just do it
before taking the lock. Drop the map_pages label and the relock flow, so
the sequence becomes fault, allocate, then lock, validate, map and
unlock. No functional change intended.

Signed-off-by: Honglei Huang <honghuan@amd.com>
---
 drivers/gpu/drm/drm_gpusvm.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
index 507ef6f0a60e..3496cb568836 100644
--- a/drivers/gpu/drm/drm_gpusvm.c
+++ b/drivers/gpu/drm/drm_gpusvm.c
@@ -1551,10 +1551,18 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
 	if (err)
 		goto err_free;
 
+	if (!svm_pages->dma_addr) {
+		svm_pages->dma_addr =
+			kvmalloc_objs(*svm_pages->dma_addr, npages);
+		if (!svm_pages->dma_addr) {
+			err = -ENOMEM;
+			goto err_free;
+		}
+	}
+
 	*state = (struct dma_iova_state){};
 	svm_pages->state_offset = 0;
 
-map_pages:
 	/*
 	 * Perform all dma mappings under the notifier lock to not
 	 * access freed pages. A notifier will either block on
@@ -1575,18 +1583,6 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
 		goto retry;
 	}
 
-	if (!svm_pages->dma_addr) {
-		/* Unlock and restart mapping to allocate memory. */
-		drm_gpusvm_notifier_unlock(gpusvm);
-		svm_pages->dma_addr =
-			kvmalloc_objs(*svm_pages->dma_addr, npages);
-		if (!svm_pages->dma_addr) {
-			err = -ENOMEM;
-			goto err_free;
-		}
-		goto map_pages;
-	}
-
 	zdd = NULL;
 	pagemap = NULL;
 	num_dma_mapped = 0;
-- 
2.34.1