Fix discrepancy between VDSO based gettimeofday() and sys_gettimeofday().

On platforms that copy sys_tz into the vdso (currently only x86_64, soon to
include powerpc), it is possible for the vdso to get out of sync if a user
calls (admittedly unusual) settimeofday(NULL, ptr).

This patch adds a hook for architectures that set
CONFIG_GENERIC_TIME_VSYSCALL to ensure when sys_tz is updated they can also
updatee their copy in the vdso.

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Tony Luck <tony.luck@intel.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/time.c b/kernel/time.c
index 2d5b6a682138..d9725bdcd045 100644
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -30,6 +30,7 @@
 #include <linux/module.h>
 #include <linux/timex.h>
 #include <linux/capability.h>
+#include <linux/clocksource.h>
 #include <linux/errno.h>
 #include <linux/syscalls.h>
 #include <linux/security.h>
@@ -158,6 +159,7 @@ int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
         if (tz) {
                 /* SMP safe, global irq locking makes it work. */
                 sys_tz = *tz;
+                update_vsyscall_tz();
                 if (firsttime) {
                         firsttime = 0;
                         if (!tv)