Peter Zijlstra 6428671bae locking/mutex: Optimize mutex_trylock() fast-path ...

A while back Viro posted a number of 'interesting' mutex_is_locked()
users on IRC, one of those was RCU.

RCU seems to use mutex_is_locked() to avoid doing mutex_trylock(), the
regular load before modify pattern.

While the use isn't wrong per se, its curious in that its needed at all,
mutex_trylock() should be good enough on its own to avoid the pointless
cacheline bounces.

So fix those and remove the mutex_is_locked() (ab)use from RCU.

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paul McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <Waiman.Long@hpe.com>
Link: http://lkml.kernel.org/r/20160601185815.GW3190@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2016-06-08 15:17:01 +02:00

..

bpf

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2016-05-31 22:28:28 -07:00

configs

kconfig: add xenconfig defconfig helper

2015-06-16 11:04:29 +01:00

debug

mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings

2016-02-22 08:51:37 +01:00

events

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-05-25 17:05:40 -07:00

gcov

gcov: disable for COMPILE_TEST

2016-05-10 17:12:49 +02:00

irq

radix-tree: introduce radix_tree_empty

2016-05-20 17:58:30 -07:00

livepatch

Merge branches 'for-4.7/core', 'for-4.7/livepatching-doc' and 'for-4.7/livepatching-ppc64' into for-linus

2016-05-17 12:06:35 +02:00

locking

locking/rwsem: Streamline the rwsem_optimistic_spin() code

2016-06-08 15:17:00 +02:00

power

PM / Hibernate: Call flush_icache_range() on pages restored in-place

2016-04-28 13:35:48 +01:00

printk

printk/nmi: flush NMI messages on the system panic

2016-05-20 17:58:30 -07:00

rcu

locking/mutex: Optimize mutex_trylock() fast-path

2016-06-08 15:17:01 +02:00

sched

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-05-25 17:11:43 -07:00

time

timer: Export destroy_hrtimer_on_stack()

2016-05-31 11:44:08 -07:00

trace

Merge tag 'trace-v4.7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2016-05-22 19:40:39 -07:00

.gitignore

certs: add .gitignore to stop git nagging about x509_certificate_list

2015-10-21 15:18:35 +01:00

acct.c

acct: check FMODE_CAN_WRITE

2015-04-11 22:27:55 -04:00

async.c

async: export current_is_async()

2015-11-19 17:51:48 +01:00

audit_fsnotify.c

wrappers for ->i_mutex access

2016-01-22 18:04:28 -05:00

audit_tree.c

audit: cleanup prune_tree_thread

2016-04-04 09:46:47 -04:00

audit_watch.c

don't bother with ->d_inode->i_sb - it's always equal to ->d_sb

2016-04-10 17:11:51 -04:00

audit.c

Merge branch 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit

2016-05-18 18:46:55 -07:00

audit.h

security: Make inode argument of inode_getsecid non-const

2015-12-24 11:09:39 -05:00

auditfilter.c

audit: Fix typo in comment

2016-02-08 11:25:39 -05:00

auditsc.c

Merge branch 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit

2016-05-18 18:46:55 -07:00

backtracetest.c

…

bounds.c

page-cgroup: get rid of NR_PCG_FLAGS

2014-08-08 15:57:18 -07:00

capability.c

kernel: conditionally support non-root users, groups and capabilities

2015-04-15 16:35:22 -07:00

cgroup_freezer.c

cgroup: kill cgrp_ss_priv[CGROUP_CANFORK_COUNT] and friends

2015-12-03 10:24:08 -05:00

cgroup_pids.c

cgroup_pids: fix a typo.

2015-12-14 14:54:37 -05:00

cgroup.c

cgroup: fix compile warning

2016-05-12 11:05:27 -04:00

compat.c

compat: cleanup coding in compat_get_bitmap() and compat_put_bitmap()

2015-06-04 23:57:18 +02:00

configs.c

…

context_tracking.c

context_tracking: Switch to new static_branch API

2015-11-24 09:56:43 +01:00

cpu_pm.c

kernel/cpu_pm: fix cpu_cluster_pm_exit comment

2015-09-03 02:42:20 +02:00

cpu.c

sched/hotplug: Make activate() the last hotplug step

2016-05-06 14:58:25 +02:00

cpuset.c

cpuset: use static key better and convert to new API

2016-05-19 19:12:14 -07:00

crash_dump.c

crash_dump: Make is_kdump_kernel() accessible from modules

2014-08-25 15:42:19 -07:00

cred.c

kmemcg: account certain kmem allocations to memcg

2016-01-14 16:00:49 -08:00

delayacct.c

kmemcg: account certain kmem allocations to memcg

2016-01-14 16:00:49 -08:00

dma.c

…

elfcore.c

…

exec_domain.c

Remove rest of exec domains.

2015-04-12 21:03:31 +02:00

exit.c

wait: allow sys_waitid() to accept __WNOTHREAD/__WCLONE/__WALL

2016-05-23 17:04:14 -07:00

extable.c

kernel/extable.c: remove duplicated include

2015-09-10 13:29:01 -07:00

fork.c

mm: oom_reaper: remove some bloat

2016-05-26 15:35:44 -07:00

freezer.c

freezer: remove obsolete comments in __thaw_task()

2014-10-21 23:44:20 +02:00

futex_compat.c

ptrace: use fsuid, fsgid, effective creds for fs access checks

2016-01-20 17:09:18 -08:00

futex.c

x86: remove more uaccess_32.h complexity

2016-05-22 17:21:27 -07:00

groups.c

kernel: conditionally support non-root users, groups and capabilities

2015-04-15 16:35:22 -07:00

hung_task.c

kernel/hung_task.c: use timeout diff when timeout is updated

2016-03-22 15:36:02 -07:00

irq_work.c

treewide: Remove old email address

2015-11-23 09:44:58 +01:00

jump_label.c

treewide: Remove old email address

2015-11-23 09:44:58 +01:00

kallsyms.c

kallsyms: add support for relative offsets in kallsyms address table

2016-03-15 16:55:16 -07:00

kcmp.c

ptrace: use fsuid, fsgid, effective creds for fs access checks

2016-01-20 17:09:18 -08:00

Kconfig.freezer

…

Kconfig.hz

…

Kconfig.locks

locking/qrwlock: Rename QUEUE_RWLOCK to QUEUED_RWLOCKS

2015-05-12 09:46:00 +02:00

Kconfig.preempt

…

kcov.c

kcov: don't profile branches in kcov

2016-04-28 19:34:04 -07:00

kexec_core.c

s390/kexec: consolidate crash_map/unmap_reserved_pages() and arch_kexec_protect(unprotect)_crashkres()

2016-05-23 17:04:14 -07:00

kexec_file.c

kexec: introduce a protection mechanism for the crashkernel reserved memory

2016-05-23 17:04:14 -07:00

kexec_internal.h

kexec: move some memembers and definitions within the scope of CONFIG_KEXEC_FILE

2016-01-20 17:09:18 -08:00

kexec.c

s390/kexec: consolidate crash_map/unmap_reserved_pages() and arch_kexec_protect(unprotect)_crashkres()

2016-05-23 17:04:14 -07:00

kmod.c

kmod: don't run async usermode helper as a child of kworker thread

2015-10-23 17:55:10 +09:00

kprobes.c

perf/x86/hw_breakpoints: Disallow kernel breakpoints unless kprobe-safe

2015-08-04 10:16:54 +02:00

ksysfs.c

rcu: Remove TINY_RCU bloat from pointless boot parameters

2015-12-07 16:59:37 -08:00

kthread.c

kernel/kthread.c:kthread_create_on_node(): clarify documentation

2015-09-04 16:54:41 -07:00

latencytop.c

sched/debug: Make schedstats a runtime tunable that is disabled by default

2016-02-09 11:54:23 +01:00

Makefile

ELF/MIPS build fix

2016-05-23 17:04:14 -07:00

membarrier.c

sys_membarrier(): system-wide memory barrier (generic, x86)

2015-09-11 15:21:34 -07:00

memremap.c

memremap: add arch specific hook for MEMREMAP_WB mappings

2016-04-04 10:26:41 +02:00

module_signing.c

KEYS: Move the point of trust determination to __key_link()

2016-04-11 22:43:43 +01:00

module-internal.h

…

module.c

module: preserve Elf information for livepatch modules

2016-04-01 15:00:10 +02:00

notifier.c

Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-09-01 08:40:25 -07:00

nsproxy.c

cgroup: introduce cgroup namespaces

2016-02-16 13:04:58 -05:00

padata.c

kernel/padata.c: hide unused functions

2016-05-19 19:12:14 -07:00

panic.c

printk/nmi: flush NMI messages on the system panic

2016-05-20 17:58:30 -07:00

params.c

Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

2015-11-09 15:53:39 -08:00

pid_namespace.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2014-12-16 15:53:03 -08:00

pid.c

remove lots of IS_ERR_VALUE abuses

2016-05-27 15:26:11 -07:00

profile.c

profile: hide unused functions when !CONFIG_PROC_FS

2016-03-22 15:36:02 -07:00

ptrace.c

ptrace: change __ptrace_unlink() to clear ->ptrace under ->siglock

2016-03-22 15:36:02 -07:00

range.c

kernel: avoid overflow in cmp_range

2015-01-17 10:02:23 +13:00

reboot.c

kexec: split kexec_load syscall from kexec core code

2015-09-10 13:29:01 -07:00

relay.c

wrappers for ->i_mutex access

2016-01-22 18:04:28 -05:00

resource.c

/proc/iomem: only expose physical resource addresses to privileged users

2016-04-14 12:56:09 -07:00

seccomp.c

Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus

2016-05-19 10:02:26 -07:00

signal.c

kernel/signal.c: convert printk(KERN_<LEVEL> ...) to pr_<level>(...)

2016-05-23 17:04:14 -07:00

smp.c

Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-03-15 13:50:29 -07:00

smpboot.c

cpu/hotplug: Unpark smpboot threads from the state machine

2016-03-01 20:36:56 +01:00

smpboot.h

cpu/hotplug: Create hotplug threads

2016-03-01 20:36:56 +01:00

softirq.c

arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections

2016-03-25 16:37:42 -07:00

stacktrace.c

stacktrace: introduce snprint_stack_trace for buffer output

2014-12-13 12:42:48 -08:00

stop_machine.c

kernel/stop_machine.c: remove CONFIG_SMP dependencies

2016-01-16 11:17:24 -08:00

sys_ni.c

vfs: add copy_file_range syscall and vfs helper

2015-12-01 14:00:53 -05:00

sys.c

prctl: make PR_SET_THP_DISABLE wait for mmap_sem killable

2016-05-23 17:04:14 -07:00

sysctl_binary.c

kernel/sysctl_binary.c: use generic UUID library

2016-05-20 17:58:30 -07:00

sysctl.c

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-05-25 17:05:40 -07:00

task_work.c

task_work: remove fifo ordering guarantee

2015-09-05 13:46:58 -07:00

taskstats.c

taskstats: use the libnl API to align nlattr on 64-bit

2016-04-23 20:13:25 -04:00

test_kprobes.c

kernel/test_kprobes.c: use current logging functions

2014-08-08 15:57:18 -07:00

torture.c

rcutorture: Dump trace buffer upon shutdown

2016-04-21 13:47:04 -07:00

tracepoint.c

kernel/...: convert pr_warning to pr_warn

2016-03-22 15:36:02 -07:00

tsacct.c

time, acct: Drop irq save & restore from __acct_update_integrals()

2016-02-29 09:53:09 +01:00

uid16.c

groups: Consolidate the setgroups permission checks

2014-12-05 17:19:27 -06:00

up.c

…

user_namespace.c

kernel/*: switch to memdup_user_nul()

2016-01-04 10:27:55 -05:00

user-return-notifier.c

scheduler: Replace __get_cpu_var with this_cpu_ptr

2014-08-26 13:45:45 -04:00

user.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2014-12-17 12:31:40 -08:00

utsname_sysctl.c

sysctl: convert use of typedef ctl_table to struct ctl_table

2014-06-06 16:08:16 -07:00

utsname.c

copy address of proc_ns_ops into ns_common

2014-12-04 14:34:47 -05:00

watchdog.c

watchdog: don't run proc_watchdog_update if new value is same as old

2016-03-17 15:09:34 -07:00

workqueue_internal.h

sched/core: Get rid of 'cpu' argument in wq_worker_sleeping()

2016-03-02 10:28:47 -05:00

workqueue.c

debugobjects: insulate non-fixup logic related to static obj from fixup callbacks

2016-05-19 19:12:14 -07:00