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, 5 insertions, 0 deletions

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 16ea3374dddf..107787aacb64 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -221,10 +221,15 @@ extern void clocksource_resume(void);
 
 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
 extern void update_vsyscall(struct timespec *ts, struct clocksource *c);
+extern void update_vsyscall_tz(void);
 #else
 static inline void update_vsyscall(struct timespec *ts, struct clocksource *c)
 {
 }
+
+static inline void update_vsyscall_tz(void)
+{
+}
 #endif
 
 #endif /* _LINUX_CLOCKSOURCE_H */