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.  CKPT_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 CKPT_COPY_ARRAY
    Feb 27:
            . Changed CKPT_COPY() to use assignment, eliminating the need
              for the CKPT_COPY_BIT() macro
            . Add CKPT_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>
Acked-by: Serge E. Hallyn <se...@us.ibm.com>
Tested-by: Serge E. Hallyn <se...@us.ibm.com>

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 81e2150..9eeb71c 100644
--- a/include/linux/checkpoint.h
+++ b/include/linux/checkpoint.h
@@ -260,6 +260,34 @@ static inline int ckpt_validate_errno(int errno)
        return (errno >= 0) && (errno < MAX_ERRNO);
 }
 
+/* useful macros to copy fields and buffers to/from ckpt_hdr_xxx structures */
+#define CKPT_CPT 1
+#define CKPT_RST 2
+
+#define CKPT_COPY(op, SAVE, LIVE)                                      \
+       do {                                                    \
+               if (op == CKPT_CPT)                             \
+                       SAVE = LIVE;                            \
+               else                                            \
+                       LIVE = SAVE;                            \
+       } while (0)
+
+/*
+ * Copy @count items from @LIVE to @SAVE if op is CKPT_CPT (otherwise,
+ * copy in the reverse direction)
+ */
+#define CKPT_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 == CKPT_CPT)                                     \
+                       memcpy(SAVE, LIVE, count * sizeof(*SAVE));      \
+               else                                                    \
+                       memcpy(LIVE, SAVE, count * sizeof(*SAVE));      \
+       } while (0)
+
+
 /* debugging flags */
 #define CKPT_DBASE     0x1             /* anything */
 #define CKPT_DSYS      0x2             /* generic (system) */
-- 
1.6.3.3

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