Liang Chen 1c263d0e54 kthread: Do not preempt current task if it is going to call schedule() ... commit 26c7295be0 upstream. when we create a kthread with ktrhead_create_on_cpu(),the child thread entry is ktread.c:ktrhead() which will be preempted by the parent after call complete(done) while schedule() is not called yet,then the parent will call wait_task_inactive(child) but the child is still on the runqueue, so the parent will schedule_hrtimeout() for 1 jiffy,it will waste a lot of time,especially on startup. parent child ktrhead_create_on_cpu() wait_fo_completion(&done) -----> ktread.c:ktrhead() |----- complete(done);--wakeup and preempted by parent kthread_bind() <------------| |-> schedule();--dequeue here wait_task_inactive(child) | schedule_hrtimeout(1 jiffy) -| So we hope the child just wakeup parent but not preempted by parent, and the child is going to call schedule() soon,then the parent will not call schedule_hrtimeout(1 jiffy) as the child is already dequeue. The same issue for ktrhead_park()&&kthread_parkme(). This patch can save 120ms on rk312x startup with CONFIG_HZ=300. Signed-off-by: Liang Chen <cl@rock-chips.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Link: https://lkml.kernel.org/r/20200306070133.18335-2-cl@rock-chips.com Signed-off-by: Chanho Park <chanho61.park@samsung.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-08-26 10:31:00 +02:00
..
bpf	bpf: Fix map leak in HASH_OF_MAPS map	2020-08-05 10:06:03 +02:00
cgroup	cgroup: add missing skcd->no_refcnt check in cgroup_sk_clone()	2020-08-19 08:14:47 +02:00
configs	kconfig: tinyconfig: remove stale stack protector fixups	2018-06-15 07:15:28 +09:00
debug	kgdb: Avoid suspicious RCU usage warning	2020-07-09 09:37:10 +02:00
dma	dma-debug: add a schedule point in debug_dma_dump_mappings()	2020-01-04 19:12:43 +01:00
events	uprobes: Change handle_swbp() to send SIGTRAP with si_code=SI_KERNEL, to fix GDB regression	2020-07-29 10:16:47 +02:00
gcov	kernel/gcov/fs.c: gcov_seq_next() should increase position index	2020-04-29 16:31:12 +02:00
irq	genirq/affinity: Make affinity setting if activated opt-in	2020-08-21 11:05:28 +02:00
livepatch	livepatch: Nullify obj->mod in klp_module_coming()'s error path	2019-10-07 18:57:10 +02:00
locking	locktorture: Print ratio of acquisitions, not failures	2020-04-23 10:30:23 +02:00
power	PM: hibernate: Freeze kernel threads in software_resume()	2020-05-06 08:13:28 +02:00
printk	printk: queue wake_up_klogd irq_work only if per-CPU areas are ready	2020-07-22 09:32:13 +02:00
rcu	rcu: Avoid data-race in rcu_gp_fqs_check_wake()	2020-02-11 04:33:55 -08:00
sched	sched: correct SD_flags returned by tl->sd_flags()	2020-08-19 08:14:47 +02:00
time	random32: update the net random state on interrupt and activity	2020-08-07 09:36:20 +02:00
trace	tracing: Use trace_sched_process_free() instead of exit() for pid tracing	2020-08-21 11:05:33 +02:00
.gitignore
acct.c	acct_on(): don't mess with freeze protection	2019-05-31 06:46:05 -07:00
async.c
audit.c	audit: fix a net reference leak in audit_list_rules_send()	2020-06-22 09:05:13 +02:00
audit.h	audit: fix a net reference leak in audit_list_rules_send()	2020-06-22 09:05:13 +02:00
audit_fsnotify.c
audit_tree.c	audit: Embed key into chunk	2019-12-13 08:51:11 +01:00
audit_watch.c	audit_get_nd(): don't unlock parent too early	2019-12-13 08:51:02 +01:00
auditfilter.c	audit: fix a net reference leak in audit_list_rules_send()	2020-06-22 09:05:13 +02:00
auditsc.c	audit: print empty EXECVE args	2019-12-01 09:17:17 +01:00
backtracetest.c
bounds.c	kbuild: fix kernel/bounds.c 'W=1' warning	2018-11-13 11:08:47 -08:00
capability.c	LSM: generalize flag passing to security_capable	2020-01-23 08:21:29 +01:00
compat.c	make 'user_access_begin()' do 'access_ok()'	2020-06-22 09:04:58 +02:00
configs.c
context_tracking.c
cpu.c	sched/core: Fix illegal RCU from offline CPUs	2020-06-22 09:05:14 +02:00
cpu_pm.c	kernel/cpu_pm: Fix uninitted local in cpu_pm	2020-06-22 09:05:28 +02:00
crash_core.c	kernel/crash_core.c: print timestamp using time64_t	2018-08-22 10:52:47 -07:00
crash_dump.c
cred.c	memcg: account security cred as well to kmemcg	2020-01-09 10:19:00 +01:00
delayacct.c
dma.c
elfcore.c	kernel/elfcore.c: include proper prototypes	2019-10-11 18:21:23 +02:00
exec_domain.c
exit.c	exit: Move preemption fixup up, move blocking operations down	2020-06-22 09:05:14 +02:00
extable.c
fail_function.c	bpf/error-inject/kprobes: Clear current_kprobe and enable preempt in kprobe	2018-06-21 12:33:19 +02:00
fork.c	fork,memcg: alloc_thread_stack_node needs to set tsk->stack	2020-01-27 14:50:58 +01:00
freezer.c	PM / reboot: Eliminate race between reboot and suspend	2018-08-06 12:35:20 +02:00
futex.c	futex: Unbreak futex hashing	2020-03-25 08:06:14 +01:00
groups.c
hung_task.c	kernel: hung_task.c: disable on suspend	2019-04-20 09:16:02 +02:00
iomem.c
irq_work.c	irq_work: Do not raise an IPI when queueing work on the local CPU	2019-05-31 06:46:19 -07:00
jump_label.c	jump_label: move 'asm goto' support test to Kconfig	2019-06-04 08:02:34 +02:00
kallsyms.c	kallsyms: Refactor kallsyms_show_value() to take cred	2020-07-16 08:17:26 +02:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt	kconfig: include kernel/Kconfig.preempt from init/Kconfig	2018-08-02 08:06:54 +09:00
kcov.c	kernel/kcov.c: mark write_comp_data() as notrace	2019-02-12 19:47:20 +01:00
kexec.c	kexec: add call to LSM hook in original kexec_load syscall	2018-07-16 12:31:57 -07:00
kexec_core.c	kexec: Allocate decrypted control pages for kdump if SME is enabled	2019-11-24 08:20:29 +01:00
kexec_file.c	treewide: Use array_size() in vzalloc()	2018-06-12 16:19:22 -07:00
kexec_internal.h
kmod.c	kmod: make request_module() return an error when autoloading is disabled	2020-04-17 10:48:52 +02:00
kprobes.c	kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler	2020-08-21 11:05:33 +02:00
ksysfs.c
kthread.c	kthread: Do not preempt current task if it is going to call schedule()	2020-08-26 10:31:00 +02:00
latencytop.c
Makefile	y2038: futex: Move compat implementation into futex.c	2019-12-01 09:17:38 +01:00
memremap.c	mm/memory_hotplug: shrink zones when offlining memory	2020-01-29 16:43:27 +01:00
module-internal.h	modsign: log module name in the event of an error	2018-07-02 11:36:17 +02:00
module.c	module: Correctly truncate sysfs sections output	2020-08-21 11:05:34 +02:00
module_signing.c	modsign: log module name in the event of an error	2018-07-02 11:36:17 +02:00
notifier.c	x86/mm: split vmalloc_sync_all()	2020-03-25 08:06:13 +01:00
nsproxy.c
padata.c	padata: purge get_cpu and reorder_via_wq from padata_do_serial	2020-05-27 17:37:36 +02:00
panic.c	kernel/panic.c: do not append newline to the stack protector panic string	2019-12-01 09:17:10 +01:00
params.c
pid.c	Fix failure path in alloc_pid()	2019-01-13 09:51:06 +01:00
pid_namespace.c	signal/pid_namespace: Fix reboot_pid_ns to use send_sig not force_sig	2019-07-26 09:14:01 +02:00
profile.c
ptrace.c	ptrace: reintroduce usage of subjective credentials in ptrace_has_cap()	2020-01-23 08:21:29 +01:00
range.c
reboot.c	PM / reboot: Eliminate race between reboot and suspend	2018-08-06 12:35:20 +02:00
relay.c	kernel/relay.c: fix memleak on destroy relay channel	2020-08-26 10:30:59 +02:00
resource.c	resource: fix locking in find_next_iomem_res()	2019-09-16 08:22:20 +02:00
rseq.c	rseq: uapi: Declare rseq_cs field as union, update includes	2018-07-10 22:18:52 +02:00
seccomp.c	LSM: generalize flag passing to security_capable	2020-01-23 08:21:29 +01:00
signal.c	signal: Extend exec_id to 64bits	2020-04-17 10:48:47 +02:00
smp.c	cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM	2019-02-12 19:47:25 +01:00
smpboot.c	smpboot: Remove cpumask from the API	2018-07-03 09:20:44 +02:00
smpboot.h
softirq.c	nohz: Fix missing tick reprogram when interrupting an inline softirq	2018-08-03 15:52:10 +02:00
stacktrace.c
stop_machine.c	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-08-13 11:25:07 -07:00
sys.c	kernel/sys.c: prctl: fix false positive in validate_prctl_map()	2019-06-15 11:54:01 +02:00
sys_ni.c	Merge branch 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-06-10 10:17:09 -07:00
sysctl.c	kernel: sysctl: make drop_caches write-only	2020-01-04 19:13:17 +01:00
sysctl_binary.c
task_work.c
taskstats.c	taskstats: fix data-race	2020-01-09 10:18:59 +01:00
test_kprobes.c	kprobes: Remove jprobe API implementation	2018-06-21 12:33:05 +02:00
torture.c	torture: Keep old-school dmesg format	2018-06-25 11:30:10 -07:00
tracepoint.c	tracepoint: Fix tracepoint array element size mismatch	2018-10-17 15:35:29 -04:00
tsacct.c
ucount.c
uid16.c
uid16.h
umh.c	coredump: fix crash when umh is disabled	2020-05-14 07:57:21 +02:00
up.c
user-return-notifier.c
user.c	userns: use irqsave variant of refcount_dec_and_lock()	2018-08-22 10:52:47 -07:00
user_namespace.c	userns: also map extents in the reverse map to kernel IDs	2018-11-13 11:09:00 -08:00
utsname.c
utsname_sysctl.c	sys: don't hold uts_sem while accessing userspace memory	2018-08-11 02:05:53 -05:00
watchdog.c	watchdog/softlockup: Enforce that timestamp is valid on boot	2020-02-24 08:34:49 +01:00
watchdog_hld.c	watchdog: Mark watchdog touch functions as notrace	2018-08-30 12:56:40 +02:00
workqueue.c	workqueue: don't use wq_select_unbound_cpu() for bound works	2020-03-18 07:14:20 +01:00
workqueue_internal.h