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Diffstat (limited to 'include/uapi/asm-generic/sembuf.h')
-rw-r--r--include/uapi/asm-generic/sembuf.h26
1 files changed, 16 insertions, 10 deletions
diff --git a/include/uapi/asm-generic/sembuf.h b/include/uapi/asm-generic/sembuf.h
index cbf9cfe977d6..0bae010f1b64 100644
--- a/include/uapi/asm-generic/sembuf.h
+++ b/include/uapi/asm-generic/sembuf.h
@@ -13,23 +13,29 @@
* everyone just ended up making identical copies without specific
* optimizations, so we may just as well all use the same one.
*
- * 64 bit architectures typically define a 64 bit __kernel_time_t,
+ * 64 bit architectures use a 64-bit __kernel_time_t here, while
+ * 32 bit architectures have a pair of unsigned long values.
* so they do not need the first two padding words.
- * On big-endian systems, the padding is in the wrong place.
*
- * Pad space is left for:
- * - 64-bit time_t to solve y2038 problem
- * - 2 miscellaneous 32-bit values
+ * On big-endian systems, the padding is in the wrong place for
+ * historic reasons, so user space has to reconstruct a time_t
+ * value using
+ *
+ * user_semid_ds.sem_otime = kernel_semid64_ds.sem_otime +
+ * ((long long)kernel_semid64_ds.sem_otime_high << 32)
+ *
+ * Pad space is left for 2 miscellaneous 32-bit values
*/
struct semid64_ds {
struct ipc64_perm sem_perm; /* permissions .. see ipc.h */
+#if __BITS_PER_LONG == 64
__kernel_time_t sem_otime; /* last semop time */
-#if __BITS_PER_LONG != 64
- unsigned long __unused1;
-#endif
__kernel_time_t sem_ctime; /* last change time */
-#if __BITS_PER_LONG != 64
- unsigned long __unused2;
+#else
+ unsigned long sem_otime; /* last semop time */
+ unsigned long sem_otime_high;
+ unsigned long sem_ctime; /* last change time */
+ unsigned long sem_ctime_high;
#endif
unsigned long sem_nsems; /* no. of semaphores in array */
unsigned long __unused3;