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Petr Mladek 37be45d49d kthread: allow to cancel kthread work 
We are going to use kthread workers more widely and sometimes we will need
to make sure that the work is neither pending nor running.

This patch implements cancel_*_sync() operations as inspired by
workqueues.  Well, we are synchronized against the other operations via
the worker lock, we use del_timer_sync() and a counter to count parallel
cancel operations.  Therefore the implementation might be easier.

First, we check if a worker is assigned.  If not, the work has newer been
queued after it was initialized.

Second, we take the worker lock.  It must be the right one.  The work must
not be assigned to another worker unless it is initialized in between.

Third, we try to cancel the timer when it exists.  The timer is deleted
synchronously to make sure that the timer call back is not running.  We
need to temporary release the worker->lock to avoid a possible deadlock
with the callback.  In the meantime, we set work->canceling counter to
avoid any queuing.

Fourth, we try to remove the work from a worker list. It might be
the list of either normal or delayed works.

Fifth, if the work is running, we call kthread_flush_work().  It might
take an arbitrary time.  We need to release the worker-lock again.  In the
meantime, we again block any queuing by the canceling counter.

As already mentioned, the check for a pending kthread work is done under a
lock.  In compare with workqueues, we do not need to fight for a single
PENDING bit to block other operations.  Therefore we do not suffer from
the thundering storm problem and all parallel canceling jobs might use
kthread_flush_work().  Any queuing is blocked until the counter gets zero.

Link: http://lkml.kernel.org/r/1470754545-17632-10-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
..
bpf Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-10-10 20:16:43 -07:00
configs config: android: enable CONFIG_SECCOMP 2016-10-11 15:06:32 -07:00
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 git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2016-10-05 10:11:24 -07:00
gcov gcov: add support for gcc version >= 6 2016-07-15 14:54:27 +09:00
irq genirq: Make function __irq_do_set_handler() static 2016-09-25 16:46:52 -04:00
livepatch livepatch/module: make TAINT_LIVEPATCH module-specific 2016-08-26 14:42:08 +02:00
locking locking/lglock: Remove lglock implementation 2016-09-22 15:25:56 +02:00
power oom, suspend: fix oom_killer_disable vs. pm suspend properly 2016-10-07 18:46:27 -07:00
printk Merge branch 'printk-cleanups' 2016-10-10 09:29:50 -07:00
rcu Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-10-03 12:15:00 -07:00
sched nmi_backtrace: generate one-line reports for idle cpus 2016-10-07 18:46:30 -07:00
time timekeeping: Fix __ktime_get_fast_ns() regression 2016-10-05 15:44:46 +02:00
trace Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2016-10-07 12:24:08 -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.c Merge branch 'stable-4.9' of git://git.infradead.org/users/pcmoore/audit 2016-10-04 14:21:41 -07:00
audit.h Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit 2016-07-29 17:54:17 -07:00
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 Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit 2016-09-01 15:55:56 -07:00
auditfilter.c audit: add fields to exclude filter by reusing user filter 2016-06-27 11:01:00 -04:00
auditsc.c Merge branch 'stable-4.9' of git://git.infradead.org/users/pcmoore/audit 2016-10-04 14:21:41 -07:00
backtracetest.c
bounds.c
capability.c kernel: Add noaudit variant of ns_capable() 2016-06-06 20:16:18 +10:00
cgroup.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2016-10-06 09:52:23 -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: Use lld instead of ld when printing pids controller events_limit 2016-06-21 15:03:36 -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.c Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-10-03 19:43:08 -07:00
cpu_pm.c kernel/cpu_pm: fix cpu_cluster_pm_exit comment 2015-09-03 02:42:20 +02:00
cpuset.c cpuset: fix non static symbol warning 2016-09-16 11:31:17 -04:00
crash_dump.c
cred.c cred: Reject inodes with invalid ids in set_create_file_as() 2016-06-30 18:05:09 -05:00
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 mm, oom: enforce exit_oom_victim on current task 2016-10-07 18:46:28 -07:00
extable.c kernel/extable.c: remove duplicated include 2015-09-10 13:29:01 -07:00
fork.c thp: reduce usage of huge zero page's atomic counter 2016-10-07 18:46:28 -07:00
freezer.c freezer, oom: check TIF_MEMDIE on the correct task 2016-07-28 16:07:41 -07:00
futex.c futex: Add some more function commentry 2016-09-05 17:20:18 +02:00
futex_compat.c ptrace: use fsuid, fsgid, effective creds for fs access checks 2016-01-20 17:09:18 -08:00
groups.c cred: simpler, 1D supplementary groups 2016-10-07 18:46:30 -07:00
hung_task.c locking/hung_task: Show all locks 2016-08-24 12:16:13 +02:00
irq_work.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
jump_label.c powerpc updates for 4.8 #2 2016-08-05 09:00:54 -04:00
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 kernel/kcov: unproxify debugfs file's fops 2016-06-15 04:56:35 -07:00
kexec.c kexec: allow architectures to override boot mapping 2016-08-02 19:35:27 -04:00
kexec_core.c kexec: add restriction on kexec_load() segment sizes 2016-08-02 19:35:31 -04:00
kexec_file.c kexec: fix double-free when failing to relocate the purgatory 2016-09-01 17:52:01 -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
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 kprobes: include <asm/sections.h> instead of <asm-generic/sections.h> 2016-10-11 15:06:31 -07:00
ksysfs.c kexec: add a kexec_crash_loaded() function 2016-08-02 19:35:30 -04:00
kthread.c kthread: allow to cancel kthread work 2016-10-11 15:06:33 -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 userns: Add per user namespace sysctls. 2016-08-08 13:18:58 -05:00
membarrier.c sys_membarrier(): system-wide memory barrier (generic, x86) 2015-09-11 15:21:34 -07:00
memremap.c mm: fix cache mode of dax pmd mappings 2016-09-09 17:34:46 -07:00
module-internal.h
module.c livepatch/module: make TAINT_LIVEPATCH module-specific 2016-08-26 14:42:08 +02:00
module_signing.c KEYS: Move the point of trust determination to __key_link() 2016-04-11 22:43:43 +01:00
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 padata: Convert to hotplug state machine 2016-09-19 21:44:30 +02:00
panic.c x86/panic: replace smp_send_stop() with kdump friendly version in panic path 2016-10-11 15:06:32 -07:00
params.c Nothing exciting, minor tweaks and cleanups. 2015-11-09 15:53:39 -08:00
pid.c remove lots of IS_ERR_VALUE abuses 2016-05-27 15:26:11 -07:00
pid_namespace.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
profile.c profile: Convert to hotplug state machine 2016-07-15 10:41:42 +02:00
ptrace.c ptrace: clear TIF_SYSCALL_TRACE on ptrace detach 2016-10-11 15:06:32 -07:00
range.c
reboot.c kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
relay.c relay: Use irq_work instead of plain timer for deferred wakeup 2016-10-11 15:06:32 -07:00
resource.c /proc/iomem: only expose physical resource addresses to privileged users 2016-04-14 12:56:09 -07:00
seccomp.c seccomp: Fix tracer exit notifications during fatal signals 2016-08-30 16:12:46 -07:00
signal.c x86/signal: Add SA_{X32,IA32}_ABI sa_flags 2016-09-14 21:28:11 +02:00
smp.c smp: Allocate smp_call_on_cpu() workqueue on stack too 2016-09-22 14:49:10 +02:00
smpboot.c kthread/smpboot: do not park in kthread_create_on_cpu() 2016-10-11 15:06:33 -07:00
smpboot.h cpu/hotplug: Create hotplug threads 2016-03-01 20:36:56 +01:00
softirq.c Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-10-03 19:43:08 -07:00
stacktrace.c
stop_machine.c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-10-03 13:39:00 -07:00
sys.c prctl: make PR_SET_THP_DISABLE wait for mmap_sem killable 2016-05-23 17:04:14 -07:00
sys_ni.c x86/pkeys: Fix pkeys build breakage for some non-x86 arches 2016-09-13 14:41:36 +02:00
sysctl.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-10-10 13:04:49 -07:00
sysctl_binary.c kernel/sysctl_binary.c: use generic UUID library 2016-05-20 17:58:30 -07:00
task_work.c task_work: use READ_ONCE/lockless_dereference, avoid pi_lock if !task_works 2016-08-02 19:35:02 -04:00
taskstats.c taskstats: use the libnl API to align nlattr on 64-bit 2016-04-23 20:13:25 -04:00
test_kprobes.c
torture.c torture: Convert torture_shutdown() to hrtimer 2016-08-22 10:01:49 -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
ucount.c mntns: Add a limit on the number of mount namespaces. 2016-08-31 07:28:35 -05:00
uid16.c cred: simpler, 1D supplementary groups 2016-10-07 18:46:30 -07:00
up.c smp: Add function to execute a function synchronously on a CPU 2016-09-05 13:52:39 +02:00
user-return-notifier.c
user.c
user_namespace.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
utsname.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
utsname_sysctl.c
watchdog.c Revert "perf/x86/intel, watchdog: Switch NMI watchdog to ref cycles on x86" 2016-07-10 20:58:36 +02:00
workqueue.c kthread: rename probe_kthread_data() to kthread_probe_data() 2016-10-11 15:06:33 -07:00
workqueue_internal.h sched/core: Get rid of 'cpu' argument in wq_worker_sleeping() 2016-03-02 10:28:47 -05:00