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Masahiro Yamada beaaddb625 kconfig: tests: test defconfig when two choices interact 
Commit fbe98bb9ed ("kconfig: Fix defconfig when one choice menu
selects options that another choice menu depends on") fixed defconfig
when two choices interact (i.e. calculating the visibility of a choice
requires to calculate another choice).

The test code in that commit log was based on the real world example,
and complicated.  So, I shrunk it down to the following:

defconfig.choice:
---8<---
CONFIG_CHOICE_VAL0=y
---8<---

---8<---
config MODULES
        def_bool y
        option modules

choice
        prompt "Choice"

config CHOICE_VAL0
        tristate "Choice 0"

config CHOICE_VAL1
        tristate "Choice 1"

endchoice

choice
        prompt "Another choice"
        depends on CHOICE_VAL0

config DUMMY
        bool "dummy"

endchoice
---8<---

Prior to commit fbe98bb9ed,

  $ scripts/kconfig/conf --defconfig=defconfig.choice Kconfig.choice

resulted in:

  CONFIG_MODULES=y
  CONFIG_CHOICE_VAL0=m
  # CONFIG_CHOICE_VAL1 is not set
  CONFIG_DUMMY=y

where the expected result would be:

  CONFIG_MODULES=y
  CONFIG_CHOICE_VAL0=y
  # CONFIG_CHOICE_VAL1 is not set
  CONFIG_DUMMY=y

Roughly, this weird behavior happened like this:

Symbols are calculated a couple of times.  First, all symbols are
calculated in conf_read().  The first 'choice' is evaluated to 'y'
due to the SYMBOL_DEF_USER flag, but sym_calc_choice() clears it
unless all of its choice values are explicitly set by the user.

conf_set_all_new_symbols() clears all SYMBOL_VALID flags.  Then, only
choices are calculated.  Here, the SYMBOL_DEF_USER for the first choice
has been forgotten, so it is evaluated to 'm'.  set_all_choice_values()
sets SYMBOL_DEF_USER again to choice symbols.

When calculating the second choice, due to 'depends on CHOICE_VAL0',
it triggers the calculation of CHOICE_VAL0.  As a result, SYMBOL_VALID
is set for CHOICE_VAL0.

Symbols except choices get the final chance of re-calculation in
conf_write().  In a normal case, CHOICE_VAL0 would be re-calculated,
then the first choice would be indirectly re-calculated with the
SYMBOL_DEF_USER which has been recalled by set_all_choice_values(),
which would be evaluated to 'y'.  But, in this case, CHOICE_VAL0 has
already been marked as SYMBOL_VALID, so this re-calculation does not
happen.  Then, =m from the conf_set_all_new_symbols() phase is written
out to the .config file.

Add a unit test for this naive case.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Ulf Magnusson <ulfalizer@gmail.com>
 		2018-03-26 02:04:04 +09:00
Documentation kconfig: rename silentoldconfig to syncconfig 2018-03-26 02:04:00 +09:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
arch Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-03-11 14:59:23 -07:00
block for-linus-20180302 2018-03-02 09:35:36 -08:00
certs certs/blacklist_nohashes.c: fix const confusion in certs blacklist 2018-02-21 15:35:43 -08:00
crypto X.509: fix NULL dereference when restricting key with unsupported_sig 2018-02-22 14:38:34 +00:00
drivers Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-03-11 14:55:15 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs 2018-03-09 09:46:14 -08:00
include pci-v4.16-fixes-3 2018-03-09 13:31:08 -08:00
init jump_label: Explicitly disable jump labels in __init code 2018-02-21 16:54:05 +01:00
ipc vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
kernel Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-03-11 14:49:49 -07:00
lib lib/test_kmod.c: fix limit check on number of test devices created 2018-03-09 16:40:02 -08:00
mm mm/page_alloc: fix memmap_init_zone pageblock alignment 2018-03-09 16:40:01 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-03-05 11:29:24 -08:00
samples - do not build samples when cross compiling (Michal Hocko) 2018-02-27 10:39:29 -08:00
scripts kconfig: tests: test defconfig when two choices interact 2018-03-26 02:04:04 +09:00
security integrity/security: fix digsig.c build error with header file 2018-02-22 20:09:08 -08:00
sound ALSA: hda: add dock and led support for HP ProBook 640 G2 2018-03-08 17:37:10 +01:00
tools Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-03-11 14:59:23 -07:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: mmu: Fix overlap between public and private memslots 2018-02-24 01:43:36 +01:00
.cocciconfig
…
.get_maintainer.ignore
…
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: ignore ASN.1 auto generated files 2018-02-14 21:05:38 +01:00
.mailmap mailmap: update Mark Yao's email address 2018-01-04 16:45:09 -08:00
COPYING
…
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Kbuild fixes for v4.16 2018-03-03 10:37:01 -08:00
Makefile kbuild: add PYTHON2 and PYTHON3 variables 2018-03-26 02:04:01 +09:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.