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chenqiwu 57e86fa16a mm: replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

    struct foo {
        int stuff;
        struct boo array[];
    };

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied.  As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

[akpm@linux-foundation.org: fix build]
Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Baoquan He <bhe@redhat.com>
Link: http://lkml.kernel.org/r/1586599916-15456-1-git-send-email-qiwuchen55@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 19:06:23 -07:00
arch powerpc/pseries/hotplug-memory: stop checking is_mem_section_removable() 2020-06-04 19:06:23 -07:00
block
certs
crypto
Documentation mm/debug: add tests validating architecture page table helpers 2020-06-04 19:06:21 -07:00
drivers device-dax: add memory via add_memory_driver_managed() 2020-06-04 19:06:23 -07:00
fs Merge branch 'akpm' (patches from Andrew) 2020-06-03 20:24:15 -07:00
include mm: replace zero-length array with flexible-array member 2020-06-04 19:06:23 -07:00
init Merge branch 'akpm' (patches from Andrew) 2020-06-03 20:24:15 -07:00
ipc
kernel kexec_file: don't place kexec images on IORESOURCE_MEM_DRIVER_MANAGED 2020-06-04 19:06:23 -07:00
lib mm/debug: add tests validating architecture page table helpers 2020-06-04 19:06:21 -07:00
LICENSES
mm mm/memory_hotplug: disable the functionality for 32b 2020-06-04 19:06:23 -07:00
net
samples
scripts
security mm: add kvfree_sensitive() for freeing sensitive data objects 2020-06-04 19:06:22 -07:00
sound
tools Merge branch 'akpm' (patches from Andrew) 2020-06-03 20:24:15 -07:00
usr
virt
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.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
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MAINTAINERS media updates for v5.8-rc1 2020-06-03 20:59:38 -07:00
Makefile
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.