On 11/30/2022 4:29 AM, Jason Gunthorpe wrote:
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
new file mode 100644
index 00000000000000..d1817472c27373
--- /dev/null
+++ b/include/linux/iommufd.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Intel Corporation
+ * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES
+ */
+#ifndef __LINUX_IOMMUFD_H
+#define __LINUX_IOMMUFD_H
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+
+struct iommufd_ctx;
+struct file;
+
+void iommufd_ctx_get(struct iommufd_ctx *ictx);
+
+#if IS_ENABLED(CONFIG_IOMMUFD)
+struct iommufd_ctx *iommufd_ctx_from_file(struct file *file);
+void iommufd_ctx_put(struct iommufd_ctx *ictx);
+#else /* !CONFIG_IOMMUFD */
+static inline struct iommufd_ctx *iommufd_ctx_from_file(struct file *file)
+{
+ return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline void iommufd_ctx_put(struct iommufd_ctx *ictx)
+{
+}
Although iommufd_ctx_get is not callded when !CONFIG_IOMMUFD, but from
the view of code iommufd_ctx_get and iommufd_ctx_put are not symmetric
when !CONFIG_IOMMUFD.
I am not sure if it is a common style in kernel code.
+#endif /* CONFIG_IOMMUFD */
+#endif
