drm/i915: Fix runtime pm handling in i915_gem_shrink

We forgot to call intel_runtime_pm_put on error, fix it!
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: cf41a8f1 ("drm/i915: Finally remove obj->mm.lock.")
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: <stable@vger.kernel.org> # v5.13+
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210830121006.2978297-9-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/i915/gem/i915_gem_shrinker.c

@@ -118,7 +118,7 @@ i915_gem_shrink(struct i915_gem_ww_ctx *ww,
 	intel_wakeref_t wakeref = 0;
 	unsigned long count = 0;
 	unsigned long scanned = 0;
-	int err;
+	int err = 0;
 
 	/* CHV + VTD workaround use stop_machine(); need to trylock vm->mutex */
 	bool trylock_vm = !ww && intel_vm_no_concurrent_access_wa(i915);
@@ -242,12 +242,15 @@ i915_gem_shrink(struct i915_gem_ww_ctx *ww,
 		list_splice_tail(&still_in_list, phase->list);
 		spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
 		if (err)
-			return err;
+			break;
 	}
 
 	if (shrink & I915_SHRINK_BOUND)
 		intel_runtime_pm_put(&i915->runtime_pm, wakeref);
 
+	if (err)
+		return err;
+
 	if (nr_scanned)
 		*nr_scanned += scanned;
 	return count;