Compiler memory barriers do not prevent the CPU from executing the code
out of order. Switch to C11 atomics. This also lets us get rid of the
mutex; instead, loop until the compare_exchange succeeds.
While here, change the return value of at_quick_exit() on failure to
the more traditional -1, matching atexit().
Sponsored by: Klara, Inc.
Reviewed by: Olivier Certner, kevans, kib
Differential Revision: https://reviews.freebsd.org/D41936
(cherry picked from commit 1dc3abb052430279e47c8922d22b30922adcf0f6)
libc: Add a rudimentary test for quick_exit(3).
Sponsored by: Klara, Inc.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D41937
(cherry picked from commit c7dd4601aeebbc1bbe131cbe6747476c124b47fe)
The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.
Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
__noreturn macro and modify the other exiting functions to use it.
The __noreturn macro, unlike __dead2, must be used BEFORE the function.
This is in line with the C and C++ specifications that place _Noreturn (c1x)
and [[noreturn]] (C++11) in front of the functions. As with __dead2, this
macro falls back to using the GCC attribute.
Unfortunately, clang currently sets the same value for the C version macro
in C99 and C1x modes, so these functions are hidden by default. At some
point before 10.0, I need to go through the headers and clean up the C1x /
C++11 visibility.
Reviewed by: brooks (mentor)
