net: atm: bring back zatm uAPI

Jiri reports that linux-atm does not build without this header.
Bring it back. It's completely dead code but we can't break
the build for user space :(

Reported-by: Jiri Slaby <jirislaby@kernel.org>
Fixes: 052e1f01bfae ("net: atm: remove support for ZeitNet ZN122x ATM devices")
Link: https://lore.kernel.org/all/8576aef3-37e4-8bae-bab5-08f82a78efd3@kernel.org/
Link: https://lore.kernel.org/r/20220810164547.484378-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

License cleanup: add SPDX license identifier to uapi header files with no license

Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.

By default are files without license information under the default
license of the kernel, which is GPLV2. Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:

NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".

otherwise syscall usage would not be possible.

Update the files which contain no license information with an SPDX
license identifier. The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception. SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Revert "include/uapi/linux/atm_zatm.h: include linux/time.h"

This reverts commit cf00713a655d ("include/uapi/linux/atm_zatm.h: include
linux/time.h").

This attempted to fix userspace breakage that no longer existed when
the patch was merged. Almost one year earlier, commit 70ba07b675b5
("atm: remove 'struct zatm_t_hist'") deleted the struct in question.

After this patch was merged, we now have to deal with people being
unable to include this header in conjunction with standard C library
headers like stdlib.h (which linux-atm does). Example breakage:
x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I. -I../.. -I./../q2931 -I./../saal \
-I. -DCPPFLAGS_TEST -I../../src/include -O2 -march=native -pipe -g \
-frecord-gcc-switches -freport-bug -Wimplicit-function-declaration \
-Wnonnull -Wstrict-aliasing -Wparentheses -Warray-bounds \
-Wfree-nonheap-object -Wreturn-local-addr -fno-strict-aliasing -Wall \
-Wshadow -Wpointer-arith -Wwrite-strings -Wstrict-prototypes -c zntune.c
In file included from /usr/include/linux/atm_zatm.h:17:0,
from zntune.c:17:
/usr/include/linux/time.h:9:8: error: redefinition of ‘struct timespec’
struct timespec {
^
In file included from /usr/include/sys/select.h:43:0,
from /usr/include/sys/types.h:219,
from /usr/include/stdlib.h:314,
from zntune.c:9:
/usr/include/time.h:120:8: note: originally defined here
struct timespec
^

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Mikko Rapeli <mikko.rapeli@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/atm_zatm.h: include linux/time.h

Fixes userspace compile error:

error: field ‘real’ has incomplete type
struct timeval real; /* real (wall-clock) time */

Signed-off-by: Mikko Rapeli <mikko.rapeli@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

atm: remove 'struct zatm_t_hist'

The zatm_t_hist structure is not used anywhere in the kernel, but is
exported to user space. As we are trying to eliminate uses of time_t
in the kernel for y2038 compatibility, the current definition triggers
checking tools because it contains 'struct timeval'.

As pointed out by Chas Williams, the only user of this structure was
the ZATM_GETHIST ioctl command that has been removed a long time ago,
and we can remove the structure as well without breaking any user
space.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Chas Williams <3chas3@gmail.com>
Cc: linux-atm-general@lists.sourceforge.net
Signed-off-by: David S. Miller <davem@davemloft.net>

UAPI: (Scripted) Disintegrate include/linux

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>