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Filename Latest commit message Latest commit date
Marco Elver 06a9030363 seqlock: Require WRITE_ONCE surrounding raw_seqcount_barrier
[ Upstream commit bf07132f96d426bcbf2098227fb680915cf44498 ]

This patch proposes to require marked atomic accesses surrounding
raw_write_seqcount_barrier. We reason that otherwise there is no way to
guarantee propagation nor atomicity of writes before/after the barrier
[1]. For example, consider the compiler tears stores either before or
after the barrier; in this case, readers may observe a partial value,
and because readers are unaware that writes are going on (writes are not
in a seq-writer critical section), will complete the seq-reader critical
section while having observed some partial state.
[1] https://lwn.net/Articles/793253/

This came up when designing and implementing KCSAN, because KCSAN would
flag these accesses as data-races. After careful analysis, our reasoning
as above led us to conclude that the best thing to do is to propose an
amendment to the raw_seqcount_barrier usage.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01 13:17:25 +02:00
arch arm64: insn: consistently handle exit text 2020-10-01 13:17:23 +02:00
block block: only call sched requeue_request() for scheduled requests 2020-09-23 12:40:37 +02:00
certs
crypto crypto: af_alg - Work around empty control messages without MSG_MORE 2020-09-03 11:27:05 +02:00
Documentation affs: fix basic permission bits to actually work 2020-09-09 19:12:34 +02:00
drivers drm/mcde: Handle pending vblank while disabling display 2020-10-01 13:17:25 +02:00
fs xfs: fix log reservation overflows when allocating large rt extents 2020-10-01 13:17:24 +02:00
include seqlock: Require WRITE_ONCE surrounding raw_seqcount_barrier 2020-10-01 13:17:25 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc
kernel module: Remove accidental change of module_enable_x() 2020-10-01 13:17:24 +02:00
lib kernel/sysctl-test: Add null pointer test for sysctl.c:proc_dointvec() 2020-10-01 13:17:10 +02:00
LICENSES
mm mm: fix double page fault on arm64 if PTE_AF is cleared 2020-10-01 13:17:12 +02:00
net ipv6_route_seq_next should increase position index 2020-10-01 13:17:25 +02:00
samples bpf: Fix fds_example SIGSEGV error 2020-08-19 08:16:03 +02:00
scripts checkpatch: fix the usage of capture group ( ... ) 2020-09-09 19:12:37 +02:00
security selinux: allow labeling before policy is loaded 2020-10-01 13:17:10 +02:00
sound ALSA: hda: enable regmap internal locking 2020-10-01 13:17:24 +02:00
tools selftests/bpf: De-flake test_tcpbpf 2020-10-01 13:17:23 +02:00
usr
virt KVM: arm/arm64: vgic: Fix potential double free dist->spis in __kvm_vgic_destroy() 2020-10-01 13:17:23 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.68 2020-09-26 18:03:16 +02:00
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.