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Masahiro Yamada 527edbc18a build_bug.h: remove most of dummy BUILD_BUG_ON stubs for Sparse 
The introduction of these dummy BUILD_BUG_ON stubs dates back to commmit
903c0c7cdc ("sparse: define dummy BUILD_BUG_ON definition for
sparse").

At that time, BUILD_BUG_ON() was implemented with the negative array
trick *and* the link-time trick, like this:

  extern int __build_bug_on_failed;
  #define BUILD_BUG_ON(condition)                                \
          do {                                                   \
                  ((void)sizeof(char[1 - 2*!!(condition)]));     \
                  if (condition) __build_bug_on_failed = 1;      \
          } while(0)

Sparse is more strict about the negative array trick than GCC because
Sparse requires the array length to be really constant.

Here is the simple test code for the macro above:

  static const int x = 0;
  BUILD_BUG_ON(x);

GCC is absolutely fine with it (-Wvla was enabled only very recently),
but Sparse warns like this:

  error: bad constant expression
  error: cannot size expression

(If you are using a newer version of Sparse, you will see a different
warning message, "warning: Variable length array is used".)

Anyway, Sparse was producing many false positives, and noisier than it
should be at that time.

With the previous commit, the leftover negative array trick is gone.
Sparse is fine with the current BUILD_BUG_ON(), which is implemented by
using the 'error' attribute.

I am keeping the stub for BUILD_BUG_ON_ZERO().  Otherwise, Sparse would
complain about the following code, which GCC is fine with:

  static const int x = 0;
  int y = BUILD_BUG_ON_ZERO(x);

Link: http://lkml.kernel.org/r/1542856462-18836-3-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-04 13:13:45 -08:00
arch Merge branch 'for-linus-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2019-01-02 18:39:22 -08:00
block for-4.21/block-20190102 2019-01-02 18:49:58 -08:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto Kconfig updates for v4.21 2018-12-29 13:03:29 -08:00
Documentation Documentation/process/coding-style.rst: don't use "extern" with function prototypes 2019-01-04 13:13:45 -08:00
drivers Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2019-01-02 18:56:59 -08:00
firmware firmware: refactor firmware/Makefile 2018-12-23 10:10:32 +09:00
fs fs/proc/base.c: slightly faster /proc/*/limits 2019-01-04 13:13:45 -08:00
include build_bug.h: remove most of dummy BUILD_BUG_ON stubs for Sparse 2019-01-04 13:13:45 -08:00
init Merge tag 'devicetree-for-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux 2018-12-28 20:08:34 -08:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel proc/sysctl: fix return error for proc_doulongvec_minmax() 2019-01-04 13:13:45 -08:00
lib s390 updates for the 4.21 merge window 2019-01-02 18:37:01 -08:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
mm block: don't use un-ordered __set_current_state(TASK_UNINTERRUPTIBLE) 2019-01-02 10:46:03 -08:00
net NFS client updates for Linux 4.21 2019-01-02 16:35:23 -08:00
samples Merge branch 'next-seccomp' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-01-02 09:48:13 -08:00
scripts Tracing changes for v4.21: 2018-12-31 11:46:59 -08:00
security Merge branch 'next-tpm' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-01-02 11:05:43 -08:00
sound xen: features and fixes for 4.21 2018-12-26 11:35:07 -08:00
tools Merge branch 'next-seccomp' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-01-02 09:48:13 -08:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt mm/mmu_notifier: use structure for invalidate_range_start/end callback 2018-12-28 12:11:50 -08:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore kbuild: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap Merge tag 'nand/for-4.21' of git://git.infradead.org/linux-mtd into mtd/next 2018-12-18 19:59:16 +01:00
COPYING
CREDITS MAINTAINERS: update entry for MMP platform 2018-12-03 12:39:57 -08:00
Kbuild kbuild: remove unused cmd_gentimeconst 2018-12-25 00:10:30 +09:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Merge branch 'for-linus-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2019-01-02 18:39:22 -08:00
Makefile Kbuild updates for v4.21 2018-12-29 12:03:17 -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.