IB/uverbs: Export ib_umem_get()/ib_umem_release() to modules
Export ib_umem_get()/ib_umem_release() and put low-level drivers in
control of when to call ib_umem_get() to pin and DMA map userspace,
rather than always calling it in ib_uverbs_reg_mr() before calling the
low-level driver's reg_user_mr method.
Also move these functions to be in the ib_core module instead of
ib_uverbs, so that driver modules using them do not depend on
ib_uverbs.
This has a number of advantages:
- It is better design from the standpoint of making generic code a
library that can be used or overridden by device-specific code as
the details of specific devices dictate.
- Drivers that do not need to pin userspace memory regions do not
need to take the performance hit of calling ib_mem_get(). For
example, although I have not tried to implement it in this patch,
the ipath driver should be able to avoid pinning memory and just
use copy_{to,from}_user() to access userspace memory regions.
- Buffers that need special mapping treatment can be identified by
the low-level driver. For example, it may be possible to solve
some Altix-specific memory ordering issues with mthca CQs in
userspace by mapping CQ buffers with extra flags.
- Drivers that need to pin and DMA map userspace memory for things
other than memory regions can use ib_umem_get() directly, instead
of hacks using extra parameters to their reg_phys_mr method. For
example, the mlx4 driver that is pending being merged needs to pin
and DMA map QP and CQ buffers, but it does not need to create a
memory key for these buffers. So the cleanest solution is for mlx4
to call ib_umem_get() in the create_qp and create_cq methods.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
new file mode 100644
index 0000000..06307f7
--- /dev/null
+++ b/include/rdma/ib_umem.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2007 Cisco Systems. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef IB_UMEM_H
+#define IB_UMEM_H
+
+#include <linux/list.h>
+#include <linux/scatterlist.h>
+
+struct ib_ucontext;
+
+struct ib_umem {
+ struct ib_ucontext *context;
+ size_t length;
+ int offset;
+ int page_size;
+ int writable;
+ struct list_head chunk_list;
+};
+
+struct ib_umem_chunk {
+ struct list_head list;
+ int nents;
+ int nmap;
+ struct scatterlist page_list[0];
+};
+
+#ifdef CONFIG_INFINIBAND_USER_MEM
+
+struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
+ size_t size, int access);
+void ib_umem_release(struct ib_umem *umem);
+int ib_umem_page_count(struct ib_umem *umem);
+
+#else /* CONFIG_INFINIBAND_USER_MEM */
+
+#include <linux/err.h>
+
+static inline struct ib_umem *ib_umem_get(struct ib_ucontext *context,
+ unsigned long addr, size_t size,
+ int access) {
+ return ERR_PTR(-EINVAL);
+}
+static inline void ib_umem_release(struct ib_umem *umem) { }
+static inline int ib_umem_page_count(struct ib_umem *umem) { return 0; }
+
+#endif /* CONFIG_INFINIBAND_USER_MEM */
+
+#endif /* IB_UMEM_H */
