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9d4646d14d
kernel_optimize_test/kernel
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Will Deacon 9d4646d14d locking/qspinlock: Elide back-to-back RELEASE operations with smp_wmb() 
The qspinlock slowpath must ensure that the MCS node is fully initialised
before it can be reached by another other CPU. This is currently enforced
by using a RELEASE operation when updating the tail and also when linking
the node into the waitqueue, since the control dependency off xchg_tail
is insufficient to enforce sufficient ordering, see:

  95bcade33a ("locking/qspinlock: Ensure node is initialised before updating prev->next")

Back-to-back RELEASE operations may be expensive on some architectures,
particularly those that implement them using fences under the hood. We
can replace the two RELEASE operations with a single smp_wmb() fence and
use RELAXED operations for the subsequent publishing of the node.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: boqun.feng@gmail.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1524738868-31318-12-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27 09:48:52 +02:00
..
bpf bpf: sockmap remove dead check 2018-04-20 22:09:51 +02:00
cgroup Merge branch 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2018-04-03 18:00:13 -07:00
configs KVM changes for 4.16 2018-02-10 13:16:35 -08:00
debug * Fix 2032 time access issues and new compiler warnings 2018-04-12 10:21:19 -07:00
events perf: Remove superfluous allocation error check 2018-04-17 09:47:40 -03:00
gcov License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
irq genirq/affinity: Spread irq vectors among present CPUs as far as possible 2018-04-06 12:19:51 +02:00
livepatch livepatch: Allow to call a custom callback when freeing shadow variables 2018-04-17 13:42:48 +02:00
locking locking/qspinlock: Elide back-to-back RELEASE operations with smp_wmb() 2018-04-27 09:48:52 +02:00
power PM / QoS: mark expected switch fall-throughs 2018-04-09 13:49:40 +02:00
printk New features: 2018-04-10 11:27:30 -07:00
rcu Merge branches 'fixes.2018.02.23a', 'srcu.2018.02.20a' and 'torture.2018.02.20a' into HEAD 2018-02-23 15:15:41 -08:00
sched Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-15 12:43:30 -07:00
time posix-cpu-timers: Ensure set_process_cpu_timer is always evaluated 2018-04-19 12:54:57 +02:00
trace Following tracing fixes: 2018-04-26 16:22:47 -07:00
.gitignore
acct.c kernel/acct.c: fix the acct->needcheck check in check_free_space() 2018-01-04 16:45:09 -08:00
async.c kernel/async.c: revert "async: simplify lowest_in_progress()" 2018-02-06 18:32:44 -08:00
audit_fsnotify.c
audit_tree.c audit: track the owner of the command mutex ourselves 2018-02-23 11:22:22 -05:00
audit_watch.c
audit.c audit/stable-4.17 PR 20180403 2018-04-06 15:01:25 -07:00
audit.h audit: track the owner of the command mutex ourselves 2018-02-23 11:22:22 -05:00
auditfilter.c audit: deprecate the AUDIT_FILTER_ENTRY filter 2018-02-15 14:36:29 -05:00
auditsc.c audit: bail before bug check if audit disabled 2018-02-15 14:40:25 -05:00
backtracetest.c
bounds.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
capability.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compat.c mm: add kernel_move_pages() helper, move compat syscall to mm/migrate.c 2018-04-02 20:15:32 +02:00
configs.c
context_tracking.c
cpu_pm.c
cpu.c cpu/hotplug: Fix unused function warning 2018-03-15 20:34:40 +01:00
crash_core.c kexec: export PG_swapbacked to VMCOREINFO 2018-04-13 17:10:27 -07:00
crash_dump.c
cred.c
delayacct.c delayacct: Account blkio completion on the correct task 2018-01-16 03:29:36 +01:00
dma.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
elfcore.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
exec_domain.c get rid of pointless includes of fs_struct.h 2018-02-22 14:28:50 -05:00
exit.c kernel: use kernel_wait4() instead of sys_wait4() 2018-04-02 20:14:51 +02:00
extable.c extable: Make init_kernel_text() global 2018-02-21 16:54:06 +01:00
fail_function.c error-injection: Fix to prohibit jump optimization 2018-03-12 16:16:00 +01:00
fork.c fork: unconditionally clear stack on fork 2018-04-20 17:18:35 -07:00
freezer.c
futex_compat.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
futex.c pids: introduce find_get_task_by_vpid() helper 2018-02-06 18:32:46 -08:00
groups.c kernel: make groups_sort calling a responsibility group_info allocators 2017-12-14 16:00:49 -08:00
hung_task.c
irq_work.c irq/work: Improve the flag definitions 2018-01-08 19:43:15 +01:00
jump_label.c jump_label: Disable jump labels in __exit code 2018-03-20 08:57:17 +01:00
kallsyms.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk 2018-02-01 13:36:15 -08:00
kcmp.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c kcov: detect double association with a single task 2018-02-06 18:32:46 -08:00
kexec_core.c
kexec_file.c kernel/kexec_file.c: allow archs to set purgatory load address 2018-04-13 17:10:28 -07:00
kexec_internal.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kexec.c kexec: call do_kexec_load() in compat syscall directly 2018-04-02 20:15:01 +02:00
kmod.c
kprobes.c kprobes: Fix random address output of blacklist file 2018-04-25 10:27:56 -04:00
ksysfs.c
kthread.c treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts 2017-11-21 16:35:54 -08:00
latencytop.c
Makefile error-injection: Support fault injection framework 2018-01-12 17:33:38 -08:00
memremap.c kernel/memremap: Remove stale devres_free() call 2018-03-06 10:58:54 -08:00
module_signing.c
module-internal.h
module.c arch: remove obsolete architecture ports 2018-04-02 20:20:12 -07:00
notifier.c
nsproxy.c
padata.c padata: add SPDX identifier 2018-01-05 18:43:00 +11:00
panic.c taint: add taint for randstruct 2018-04-11 10:28:35 -07:00
params.c kernel/params.c: downgrade warning for unsafe parameters 2018-04-11 10:28:37 -07:00
pid_namespace.c Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-04-03 19:15:32 -07:00
pid.c xarray: add the xa_lock to the radix_tree_root 2018-04-11 10:28:39 -07:00
profile.c
ptrace.c pids: introduce find_get_task_by_vpid() helper 2018-02-06 18:32:46 -08:00
range.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
reboot.c kernel/reboot.c: add devm_register_reboot_notifier() 2017-11-17 16:10:04 -08:00
relay.c kernel/relay.c: limit kmalloc size to KMALLOC_MAX_SIZE 2018-02-21 15:35:43 -08:00
resource.c resource: fix integer overflow at reallocation 2018-04-13 17:10:27 -07:00
seccomp.c - Fix seccomp GET_METADATA to deal with field sizes correctly (Tycho Andersen) 2018-02-22 10:50:24 -08:00
signal.c Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2018-04-07 11:11:41 -07:00
smp.c smp/core: Use lockdep to assert IRQs are disabled/enabled 2017-11-08 11:13:50 +01:00
smpboot.c
smpboot.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
softirq.c softirq: Consolidate common code in tasklet_[hi]_action() 2018-03-09 11:50:55 +01:00
stacktrace.c
stop_machine.c
sys_ni.c syscalls/core: Prepare CONFIG_ARCH_HAS_SYSCALL_WRAPPER=y for compat syscalls 2018-04-05 16:59:38 +02:00
sys.c kernel: add ksys_setsid() helper; remove in-kernel call to sys_setsid() 2018-04-02 20:16:06 +02:00
sysctl_binary.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sysctl.c kernel/sysctl.c: add kdoc comments to do_proc_do{u}intvec_minmax_conv_param 2018-04-11 10:28:38 -07:00
task_work.c locking/barriers: Convert users of lockless_dereference() to READ_ONCE() 2017-12-17 13:57:15 +01:00
taskstats.c pids: introduce find_get_task_by_vpid() helper 2018-02-06 18:32:46 -08:00
test_kprobes.c kprobes: Disable the jprobes test code 2017-10-20 11:02:54 +02:00
torture.c torture: Save a line in stutter_wait(): while -> for 2017-12-11 09:18:30 -08:00
tracepoint.c tracepoint: Remove smp_read_barrier_depends() from comment 2017-12-04 10:52:56 -08:00
tsacct.c
ucount.c headers: untangle kmemleak.h from mm.h 2018-04-05 21:36:27 -07:00
uid16.c fs: add do_fchownat(), ksys_fchown() helpers and ksys_{,l}chown() wrappers 2018-04-02 20:15:59 +02:00
uid16.h kernel: provide ksys_*() wrappers for syscalls called by kernel/uid16.c 2018-04-02 20:15:30 +02:00
umh.c kernel: use kernel_wait4() instead of sys_wait4() 2018-04-02 20:14:51 +02:00
up.c
user_namespace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-11-16 12:20:15 -08:00
user-return-notifier.c
user.c efivarfs: Limit the rate for non-root to read files 2018-02-22 10:21:02 -08:00
utsname_sysctl.c
utsname.c uts: create "struct uts_namespace" from kmem_cache 2018-04-11 10:28:35 -07:00
watchdog_hld.c Merge branch 'linus' into core/urgent, to pick up dependent commits 2017-11-04 08:53:04 +01:00
watchdog.c Merge branch 'linus' into sched/core, to pick up fixes 2017-11-08 10:17:15 +01:00
workqueue_internal.h Merge branch 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2017-11-06 12:26:49 -08:00
workqueue.c Merge branch 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2018-04-03 18:00:13 -07:00