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Linus Torvalds 49beadbd47 gcc-12: disable '-Wdangling-pointer' warning for now
While the concept of checking for dangling pointers to local variables
at function exit is really interesting, the gcc-12 implementation is not
compatible with reality, and results in false positives.

For example, gcc sees us putting things on a local list head allocated
on the stack, which involves exactly those kinds of pointers to the
local stack entry:

  In function ‘__list_add’,
      inlined from ‘list_add_tail’ at include/linux/list.h:102:2,
      inlined from ‘rebuild_snap_realms’ at fs/ceph/snap.c:434:2:
  include/linux/list.h:74:19: warning: storing the address of local variable ‘realm_queue’ in ‘*&realm_27(D)->rebuild_item.prev’ [-Wdangling-pointer=]
     74 |         new->prev = prev;
        |         ~~~~~~~~~~^~~~~~

But then gcc - understandably - doesn't really understand the big
picture how the doubly linked list works, so doesn't see how we then end
up emptying said list head in a loop and the pointer we added has been
removed.

Gcc also complains about us (intentionally) using this as a way to store
a kind of fake stack trace, eg

  drivers/acpi/acpica/utdebug.c:40:38: warning: storing the address of local variable ‘current_sp’ in ‘acpi_gbl_entry_stack_pointer’ [-Wdangling-pointer=]
     40 |         acpi_gbl_entry_stack_pointer = &current_sp;
        |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~

which is entirely reasonable from a compiler standpoint, and we may want
to change those kinds of patterns, but not not.

So this is one of those "it would be lovely if the compiler were to
complain about us leaving dangling pointers to the stack", but not this
way.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-06-09 09:41:42 -07:00
Documentation MMC core: 2022-06-07 14:24:30 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch * Fix syzkaller NULL pointer dereference 2022-06-08 09:16:31 -07:00
block for-5.19/drivers-2022-06-02 2022-06-03 10:25:56 -07:00
certs cert host tools: Stop complaining about deprecated OpenSSL functions 2022-06-08 13:18:39 -07:00
crypto This update includes the following changes: 2022-05-27 18:06:49 -07:00
drivers drm: imx: fix compiler warning with gcc-12 2022-06-09 09:39:44 -07:00
fs fix for breakage in #work.fd this window 2022-06-05 17:14:03 -07:00
include A single featurelet for delay accounting. Delayed a bit 2022-06-05 16:58:27 -07:00
init This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
ipc These changes update the ipc sysctls so that they are fundamentally 2022-06-03 15:54:57 -07:00
kernel * Fix syzkaller NULL pointer dereference 2022-06-08 09:16:31 -07:00
lib Bitmap patches for 5.19-rc1 2022-06-04 14:04:27 -07:00
mm Hot fixes for 5.19-rc1. 2022-06-05 17:05:38 -07:00
net bluetooth: don't use bitmaps for random flag accesses 2022-06-05 16:28:41 -07:00
samples drm for 5.19-rc1 2022-05-25 16:18:27 -07:00
scripts cert host tools: Stop complaining about deprecated OpenSSL functions 2022-06-08 13:18:39 -07:00
security KEYS: trusted: tpm2: Fix migratable logic 2022-06-08 14:12:13 +03:00
sound USB / Thunderbolt changes for 5.19-rc1 2022-06-03 11:17:49 -07:00
tools * Fix syzkaller NULL pointer dereference 2022-06-08 09:16:31 -07:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt * Fix syzkaller NULL pointer dereference 2022-06-08 09:16:31 -07:00
.clang-format clang-format: Fix space after for_each macros 2022-05-20 19:27:16 +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 kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap Hot fixes for 5.19-rc1. 2022-06-05 17:05:38 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
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 Hot fixes for 5.19-rc1. 2022-06-05 17:05:38 -07:00
Makefile gcc-12: disable '-Wdangling-pointer' warning for now 2022-06-09 09:41:42 -07:00
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.