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Eric W. Biederman 893d4d9c62 s390/exit: remove dead reference to do_exit from copy_thread 
My s390 assembly is not particularly good so I have read the history
of the reference to do_exit copy_thread and have been able to
verify that do_exit is not used.

The general argument is that s390 has been changed to use the generic
kernel_thread and kernel_execve and the generic versions do not call
do_exit.  So it is strange to see a do_exit reference sitting there.

The history of the do_exit reference in s390's version of copy_thread
seems conclusive that the do_exit reference is something that lingers
and should have been removed several years ago.

Up through 8d19f15a60be ("[PATCH] s390 update (1/27): arch.")  the
s390 code made a call to the exit(2) system call when a kernel thread
finished.  Then kernel_thread_starter was added which branched
directly to the value in register 11 when the kernel thread finshed.
The value in register 11 was set in kernel_thread to
"regs.gprs[11] = (unsigned long) do_exit"

In commit 37fe5d41f6 ("s390: fold kernel_thread_helper() into
ret_from_fork()") kernel_thread_starter was moved into entry.S and
entry64.S unchanged (except for the syntax differences between inline
assemly and in the assembly file).

In commit f9a7e025df ("s390: switch to generic kernel_thread()") the
assignment to "gprs[11]" was moved into copy_thread from the old
kernel_thread.  The helper kernel_thread_starter was still being used
and was still branching to "%r11" at the end.

In commit 30dcb0996e ("s390: switch to saner kernel_execve()
semantics") kernel_thread_starter was changed to unconditionally
branch to sysc_tracenogo instead to %r11 which held the value of
do_exit.  Unfortunately copy_thread was not updated to stop passing
do_exit in "gprs[11]".

In commit 56e62a7370 ("s390: convert to generic entry")
kernel_thread_starter was replaced by __ret_from_fork.  And the code
still continued to pass do_exit in "gprs[11]" despite __ret_from_fork
not caring in the slightest.

Remove this dead reference to do_exit to make it clear that s390 is
not doing anything with do_exit in copy_thread.

History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git

Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Fixes: 30dcb0996e ("s390: switch to saner kernel_execve() semantics")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/20211208202532.16409-1-ebiederm@xmission.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2021-12-16 19:58:06 +01:00
arch s390/exit: remove dead reference to do_exit from copy_thread 2021-12-16 19:58:06 +01:00
block block: call rq_qos_done() before ref check in batch completions 2021-11-26 09:53:23 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
Documentation Power management fixes for 5.16-rc4 2021-12-03 12:22:56 -08:00
drivers s390/vfio-ap: add status attribute to AP queue device's sysfs dir 2021-12-06 14:42:26 +01:00
fs Fixes for 5.16-rc3: 2021-12-04 17:22:53 -08:00
include - Properly init uclamp_flags of a runqueue, on first enqueuing 2021-12-05 08:53:31 -08:00
init kbuild: Fix -Wimplicit-fallthrough=5 error for GCC 5.x and 6.x 2021-11-14 18:59:49 -08:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-11-20 10:35:54 -08:00
kernel - Prevent a tick storm when a dedicated timekeeper CPU in nohz_full 2021-12-05 08:58:52 -08:00
lib siphash: use _unaligned version by default 2021-11-29 19:50:50 -08:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm Fixes for 5.16 folios: 2021-11-25 10:13:56 -08:00
net Networking fixes for 5.16-rc4, including fixes from wireless, 2021-12-02 11:22:06 -08:00
samples s390 updates for 5.16-rc2 2021-11-20 10:55:50 -08:00
scripts Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid 2021-11-24 09:44:13 -08:00
security selinux: fix NULL-pointer dereference when hashtab allocation fails 2021-11-19 16:11:39 -05:00
sound sound fixes for 5.16-rc4 2021-12-01 10:07:39 -08:00
tools - Fix a couple of SWAPGS fencing issues in the x86 entry code 2021-12-05 08:43:35 -08:00
usr initramfs: Check timestamp to prevent broken cpio archive 2021-10-24 13:48:40 +09:00
virt KVM: downgrade two BUG_ONs to WARN_ON_ONCE 2021-11-26 06:43:28 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap MAINTAINERS: update email address of Christian Borntraeger 2021-11-18 17:50:54 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS TTY/Serial fixes for 5.16-rc4 2021-12-05 09:13:20 -08:00
Makefile Linux 5.16-rc4 2021-12-05 14:08:22 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.