time: Make settimeofday error checking work again

In commit 86d3473 some of the checking for a valid timeval
was subtley changed which caused -EINVAL to be returned whenever
the timeval was null.

However, it is possible to set the timezone data while specifying
a NULL timeval, which is usually done to handle systems where the
RTC keeps local time instead of UTC. Thus the patch causes such
systems to have the time incorrectly set.

This patch addresses the issue by handling the error conditionals
in the same way as was done previously.

Fixes: 86d3473 "time: Introduce do_sys_settimeofday64()"
Reported-by: Mika Westerberg <[email protected]>
Signed-off-by: John Stultz <[email protected]>
Tested-by: Mika Westerberg <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Richard Cochran <[email protected]>
Cc: Shuah Khan <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

Author: johnstultz-work

include/linux/timekeeping.h

@@ -21,6 +21,9 @@ static inline int do_sys_settimeofday(const struct timespec *tv,
 	struct timespec64 ts64;
 
 	if (!tv)
+		return do_sys_settimeofday64(NULL, tz);
+
+	if (!timespec_valid(tv))
 		return -EINVAL;
 
 	ts64 = timespec_to_timespec64(*tv);