commit 9a447c6472947bce97e8b90b7f3f97bd7cd9f3ed
Author: mjw <mjw@a5019735-40e9-0310-863c-91ae7b9d1cf9>
Date:   Wed Feb 17 20:53:34 2016 +0000

    Bug 359201 futex syscall skips argument 5 if op is FUTEX_WAIT_BITSET
    
    git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15793 a5019735-40e9-0310-863c-91ae7b9d1cf9

diff --git a/coregrind/m_syswrap/syswrap-linux.c b/coregrind/m_syswrap/syswrap-linux.c
index f796969..b57436c 100644
--- a/coregrind/m_syswrap/syswrap-linux.c
+++ b/coregrind/m_syswrap/syswrap-linux.c
@@ -1154,13 +1154,16 @@ PRE(sys_futex)
             return;
       }
       if (*(vki_u32 *)ARG1 != ARG3) {
-         PRE_REG_READ5(long, "futex",
+         PRE_REG_READ4(long, "futex",
                        vki_u32 *, futex, int, op, int, val,
-                       struct timespec *, utime, int, dummy);
+                       struct timespec *, utime);
       } else {
-         PRE_REG_READ6(long, "futex",
+        /* Note argument 5 is unused, but argument 6 is used.
+           So we cannot just PRE_REG_READ6. Read argument 6 separately.  */
+         PRE_REG_READ4(long, "futex",
                        vki_u32 *, futex, int, op, int, val,
-                       struct timespec *, utime, int, dummy, int, val3);
+                       struct timespec *, utime);
+         PRA6("futex",int,val3);
       }
       break;
    case VKI_FUTEX_WAKE_BITSET: