y2038: rename itimerval to __kernel_old_itimerval

Take the renaming of timeval and timespec one level further,
also renaming itimerval to __kernel_old_itimerval, to avoid
namespace conflicts with the user-space structure that may
use 64-bit time_t members.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

y2038: uapi: change __kernel_time_t to __kernel_old_time_t

This is mainly a patch for clarification, and to let us remove
the time_t definition from the kernel to prevent new users from
creeping in that might not be y2038-safe.

All remaining uses of 'time_t' or '__kernel_time_t' are part of
the user API that cannot be changed by that either have a
replacement or that do not suffer from the y2038 overflow.

Acked-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

y2038: add __kernel_old_timespec and __kernel_old_time_t

The 'struct timespec' definition can no longer be part of the uapi headers
because it conflicts with a a now incompatible libc definition. Also,
we really want to remove it in order to prevent new uses from creeping in.

The same namespace conflict exists with time_t, which should also be
removed. __kernel_time_t could be used safely, but adding 'old' in the
name makes it clearer that this should not be used for new interfaces.

Add a replacement __kernel_old_timespec structure and __kernel_old_time_t
along the lines of __kernel_old_timeval.

Acked-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

time: Add time_types.h

sys/time.h is the mandated include for many time related
defines. However, linux/time.h overlaps sys/time.h
significantly and this makes including both from userspace
or one from the other impossible.

This also means that userspace can get away with including
sys/time.h whenever it needs linux/time.h and this is what's
been happening in the user world usually.

But, we have new data types that we plan to use in the uapi time
interfaces also defined in the linux/time.h. But, we are unable
to use these types when sys/time.h is included.

Hence, move the new types to a new header, time_types.h.
We intend to eventually have all the uapi defines that the kernel
uses defined in this header.
Note that the plan is to replace uapi interfaces with timeval to
use __kernel_old_timeval, timespec to use __kernel_old_timespec etc.

Reported-by: Ran Rozenstein <ranro@mellanox.com>
Fixes: 9718475e6908 ("socket: Add SO_TIMESTAMPING_NEW")
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>