linux/init
Arnd Bergmann 3f2bedabb6 futex: Ensure futex_atomic_cmpxchg_inatomic() is present
The boot-time detection of futex_atomic_cmpxchg_inatomic() has a bug on
some 32-bit arm builds, and Thomas Gleixner suggested that setting
CONFIG_HAVE_FUTEX_CMPXCHG would avoid the problem, as it is always present
anyway.

Looking into which other architectures could do the same showed that almost
all architectures have it, the exceptions being:

 - some old 32-bit MIPS uniprocessor cores without ll/sc
 - one xtensa variant with no SMP
 - 32-bit SPARC when built for SMP

Fix MIPS And Xtensa by rearranging the generic code to let it be used
as a fallback.

For SPARC, the SMP definition just ends up turning off futex anyway, so
this can be done at Kconfig time instead. Note that sparc32 glibc requires
the CASA instruction for its mutexes anyway, which is only available when
running on SPARCv9 or LEON CPUs, but needs to be implemented in the sparc32
kernel for those.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Rich Felker <dalias@libc.org>
Link: https://lore.kernel.org/r/20211026100432.1730393-1-arnd@kernel.org
2021-11-25 00:02:28 +01:00
..
calibrate.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
do_mounts_initrd.c Merge branch 'hch.init_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 09:40:34 -07:00
do_mounts_rd.c init: add an init_unlink helper 2020-07-31 08:17:52 +02:00
do_mounts.c init: don't panic if mount_nodev_root failed 2021-09-19 22:24:52 -04:00
do_mounts.h init: add an init_mknod helper 2020-07-31 08:17:54 +02:00
init_task.c sched: Introduce task_struct::user_cpus_ptr to track requested affinity 2021-08-20 12:33:00 +02:00
initramfs.c memblock: use memblock_free for freeing virtual pointers 2021-11-06 13:30:41 -07:00
Kconfig futex: Ensure futex_atomic_cmpxchg_inatomic() is present 2021-11-25 00:02:28 +01:00
main.c Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
Makefile preempt: Restore preemption model selection configs 2021-11-11 13:09:33 +01:00
noinitramfs.c init: move usermodehelper_enable() to populate_rootfs() 2021-09-08 11:50:27 -07:00
version.c kbuild: add an elfnote for whether vmlinux is built with lto 2021-04-25 05:25:42 +09:00