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>

1 files changed, 4 insertions, 24 deletions

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 5342ac64ed1a..47cefca59c89 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -5,7 +5,7 @@
  * Copyright (c) 2004 Topspin Corporation.  All rights reserved.
  * Copyright (c) 2004 Voltaire Corporation.  All rights reserved.
  * Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
- * Copyright (c) 2005, 2006 Cisco Systems.  All rights reserved.
+ * Copyright (c) 2005, 2006, 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
@@ -710,6 +710,7 @@ struct ib_ucontext {
         struct list_head        qp_list;
         struct list_head        srq_list;
         struct list_head        ah_list;
+        int                     closing;
 };
 
 struct ib_uobject {
@@ -723,23 +724,6 @@ struct ib_uobject {
         int                     live;
 };
 
-struct ib_umem {
-        unsigned long           user_base;
-        unsigned long           virt_base;
-        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];
-};
-
 struct ib_udata {
         void __user *inbuf;
         void __user *outbuf;
@@ -752,11 +736,6 @@ struct ib_udata {
          ((void *) &((struct ib_umem_chunk *) 0)->page_list[1] -        \
           (void *) &((struct ib_umem_chunk *) 0)->page_list[0]))
 
-struct ib_umem_object {
-        struct ib_uobject       uobject;
-        struct ib_umem          umem;
-};
-
 struct ib_pd {
         struct ib_device       *device;
         struct ib_uobject      *uobject;
@@ -1003,7 +982,8 @@ struct ib_device {
                                                   int mr_access_flags,
                                                   u64 *iova_start);
         struct ib_mr *             (*reg_user_mr)(struct ib_pd *pd,
-                                                  struct ib_umem *region,
+                                                  u64 start, u64 length,
+                                                  u64 virt_addr,
                                                   int mr_access_flags,
                                                   struct ib_udata *udata);
         int                        (*query_mr)(struct ib_mr *mr,