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Huacai Chen e031a5f3f1 LoongArch: Support dbar with different hints
Traditionally, LoongArch uses "dbar 0" (full completion barrier) for
everything. But the full completion barrier is a performance killer, so
Loongson-3A6000 and newer processors have made finer granularity hints
available:

Bit4: ordering or completion (0: completion, 1: ordering)
Bit3: barrier for previous read (0: true, 1: false)
Bit2: barrier for previous write (0: true, 1: false)
Bit1: barrier for succeeding read (0: true, 1: false)
Bit0: barrier for succeeding write (0: true, 1: false)

Hint 0x700: barrier for "read after read" from the same address, which
is needed by LL-SC loops on old models (dbar 0x700 behaves the same as
nop if such reordering is disabled on new models).

This patch makes use of the various new hints for different kinds of
memory barriers. It brings performance improvements on Loongson-3A6000
series, while not affecting the existing models because all variants are
treated as 'dbar 0' there.

Why override queued_spin_unlock()?
After commit 01e3b958ef ("drivers: Remove explicit invocations
of mmiowb()") we need a completion barrier in queued_spin_unlock(), but
the generic implementation use smp_store_release() which only provide an
ordering barrier.

Signed-off-by: Jun Yi <yijun@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2023-06-29 20:58:44 +08:00
arch LoongArch: Support dbar with different hints 2023-06-29 20:58:44 +08:00
block block: make sure local irq is disabled when calling __blkcg_rstat_flush 2023-06-22 07:44:00 -06:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto KEYS: asymmetric: Copy sig and digest in public_key_verify_signature() 2023-06-02 15:36:23 +02:00
Documentation Merge 'irq/loongarch-fixes-6.5' into loongarch-next 2023-06-27 15:01:09 +08:00
drivers LoongArch: Add SMT (Simultaneous Multi-Threading) support 2023-06-29 20:58:43 +08:00
fs for-6.4-rc7-tag 2023-06-23 16:09:53 -07:00
include - Drop the __weak attribute from a function prototype as it otherwise 2023-06-25 10:13:17 -07:00
init Objtool changes for v6.4: 2023-04-28 14:02:54 -07:00
io_uring io_uring/net: use the correct msghdr union member in io_sendmsg_copy_hdr 2023-06-21 07:34:17 -06:00
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 workqueue: clean up WORK_* constant types, clarify masking 2023-06-23 12:08:14 -07:00
lib 19 hotfixes. 14 are cc:stable and the remainder address issues which were 2023-06-12 16:14:34 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm 19 hotfixes. 8 of these are cc:stable. 2023-06-20 17:20:22 -07:00
net netfilter pull request 23-06-21 2023-06-22 14:39:06 +02:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples samples/bpf: Drop unnecessary fallthrough 2023-05-16 19:44:05 +02:00
scripts Makefile: Add loongarch target flag for Clang compilation 2023-06-29 20:58:43 +08:00
security selinux: don't use make's grouped targets feature yet 2023-06-01 13:56:13 -04:00
sound ASoC: Fix for v6.4 2023-06-21 15:23:23 +02:00
tools Networking fixes for 6.4-rc8, including fixes from ipsec, bpf, 2023-06-22 17:59:51 -07:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Avoid illegal stage2 mapping on invalid memory slot 2023-06-22 15:14:57 -04:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig
.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
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 2023-06-25 16:29:58 -07:00
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.