From: Dan Smith <da...@us.ibm.com>

As suggested by Dave[1], this provides us a way to make the copy-in and
copy-out processes symmetric.  CR_COPY_ARRAY() provides us a way to do
the same thing but for arrays.  It's not critical, but it helps us unify
the checkpoint and restart paths for some things.

Changelog:
    Mar 04:
            . Removed semicolons
            . Added build-time check for __must_be_array in CR_COPY_ARRAY
    Feb 27:
            . Changed CR_COPY() to use assignment, eliminating the need
              for the CR_COPY_BIT() macro
            . Add CR_COPY_ARRAY() macro to help copying register arrays,
              etc
            . Move the macro definitions inside the CR #ifdef
    Feb 25:
            . Changed WARN_ON() to BUILD_BUG_ON()

Signed-off-by: Dan Smith <da...@us.ibm.com>
Signed-off-by: Oren Laadan <or...@cs.columbia.edu>

1: 
https://lists.linux-foundation.org/pipermail/containers/2009-February/015821.html
 (all the way at the bottom)
---
 include/linux/checkpoint.h |   28 ++++++++++++++++++++++++++++
 1 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
index c83e448..043535c 100644
--- a/include/linux/checkpoint.h
+++ b/include/linux/checkpoint.h
@@ -129,6 +129,34 @@ extern int do_checkpoint(struct cr_ctx *ctx, pid_t pid);
 extern int do_restart(struct cr_ctx *ctx, pid_t pid);
 
 
+/* useful macros to copy fields and buffers to/from cr_hdr_xxx structures */
+#define CR_CPT 1
+#define CR_RST 2
+
+#define CR_COPY(op, SAVE, LIVE)                                        \
+       do {                                                    \
+               if (op == CR_CPT)                               \
+                       SAVE = LIVE;                            \
+               else                                            \
+                       LIVE = SAVE;                            \
+       } while (0)
+
+/*
+ * Copy @count items from @LIVE to @SAVE if op is CR_CPT (otherwise,
+ * copy in the reverse direction)
+ */
+#define CR_COPY_ARRAY(op, SAVE, LIVE, count)                           \
+       do {                                                            \
+               (void)__must_be_array(SAVE);                            \
+               (void)__must_be_array(LIVE);                            \
+               BUILD_BUG_ON(sizeof(*SAVE) != sizeof(*LIVE));           \
+               if (op == CR_CPT)                                       \
+                       memcpy(SAVE, LIVE, count * sizeof(*SAVE));      \
+               else                                                    \
+                       memcpy(LIVE, SAVE, count * sizeof(*SAVE));      \
+       } while (0)
+
+
 #define cr_debug(fmt, args...)  \
        pr_debug("[%d:c/r:%s] " fmt, task_pid_vnr(current), __func__, ## args)
 
-- 
1.5.4.3

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