Claude review: drm/tegra: Fix iommu_map_sgtable() return value check

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

**Status: Good**

This patch introduces a local `ssize_t size` to capture the return value, checks `< 0`, and only assigns to `bo->size` on success:

```c
+	size = iommu_map_sgtable(tegra->domain, bo->iova, bo->sgt, prot);
+	if (size < 0) {
 		dev_err(tegra->drm->dev, "failed to map buffer\n");
-		err = -ENOMEM;
+		err = size;
 		goto remove;
 	}
+
+	bo->size = size;
```

The deferral of `bo->size = size` to after the error check is a nice improvement -- the old code would write zero into `bo->size` on the error path (since it checked `!bo->size`), which was harmless but sloppy. Now `bo->size` is only set on success.

One minor note: `bo->size` is declared as `size_t` in `gem.h:68`. Assigning from `ssize_t` to `size_t` is safe here because it only happens after the `< 0` check, so the value is guaranteed non-negative. This is fine.

Similarly, `err = size` narrows `ssize_t` to `int` but only on the error path (negative errno), which is safe.

No issues.

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Generated by Claude Code Patch Reviewer