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Arnd Bergmann 65df5d2ecc mtd: spi-nor: avoid holes in struct spi_mem_op 
[ Upstream commit 71c8f9cf26 ]

gcc gets confused when -ftrivial-auto-var-init=pattern is used on sparse
bit fields such as 'struct spi_mem_op', which caused the previous false
positive warning about an uninitialized variable:

drivers/mtd/spi-nor/spansion.c: error: 'op' is used uninitialized [-Werror=uninitialized]

In fact, the variable is fully initialized and gcc does not see it being
used, so the warning is entirely bogus. The problem appears to be
a misoptimization in the initialization of single bit fields when the
rest of the bytes are not initialized.

A previous workaround added another initialization, which ended up
shutting up the warning in spansion.c, though it apparently still happens
in other files as reported by Peter Foley in the gcc bugzilla. The
workaround of adding a fake initialization seems particularly bad
because it would set values that can never be correct but prevent the
compiler from warning about actually missing initializations.

Revert the broken workaround and instead pad the structure to only
have bitfields that add up to full bytes, which should avoid this
behavior in all drivers.

I also filed a new bug against gcc with what I found, so this can
hopefully be addressed in future gcc releases. At the moment, only
gcc-12 and gcc-13 are affected.

Cc: Peter Foley <pefoley2@pefoley.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110743
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108402
Link: https://godbolt.org/z/efMMsG1Kx
Fixes: 420c4495b5 ("mtd: spi-nor: spansion: make sure local struct does not contain garbage")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230719190045.4007391-1-arnd@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-08-11 12:14:26 +02:00
arch arm64/ptrace: Don't enable SVE when setting streaming SVE 2023-08-11 12:14:23 +02:00
block blk-mq: Fix stall due to recursive flush plug 2023-08-03 10:25:41 +02:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:36:19 +02:00
Documentation Documentation: kdump: Add va_kernel_pa_offset for RISCV64 2023-08-11 12:14:19 +02:00
drivers mtd: spi-nor: avoid holes in struct spi_mem_op 2023-08-11 12:14:26 +02:00
fs f2fs: fix to do sanity check on direct node in truncate_dnode() 2023-08-11 12:14:26 +02:00
include mtd: spi-nor: avoid holes in struct spi_mem_op 2023-08-11 12:14:26 +02:00
init init, x86: Move mem_encrypt_init() into arch_cpu_finalize_init() 2023-08-08 20:04:49 +02:00
io_uring io_uring: annotate offset timeout races 2023-08-11 12:14:26 +02:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel bpf: Disable preemption in bpf_event_output 2023-08-11 12:14:22 +02:00
lib debugobjects: Recheck debug_objects_enabled before reporting 2023-08-11 12:14:25 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/gup: do not return 0 from pin_user_pages_fast() for bad args 2023-08-11 12:14:25 +02:00
net Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_ready_cb 2023-08-11 12:14:24 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:14:18 +02:00
samples samples: ftrace: Save required argument registers in sample trampolines 2023-07-23 13:54:09 +02:00
scripts kbuild: rust: avoid creating temporary files 2023-07-27 08:57:06 +02:00
security security: keys: Modify mismatched function name 2023-07-27 08:56:59 +02:00
sound ASoC: wm8904: Fill the cache for WM8904_ADC_TEST_0 register 2023-08-03 10:26:12 +02:00
tools test/vsock: remove vsock_perf executable on make clean 2023-08-11 12:14:18 +02:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-08-03 10:26:01 +02:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Ben Dooks 2023-06-19 13:19:35 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 6.4-rc8, including fixes from ipsec, bpf, 2023-06-22 17:59:51 -07:00
Makefile Linux 6.4.9 2023-08-08 20:04:53 +02:00
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.