Frederic Weisbecker 8d346d438f rcu/nocb: Provide basic callback offloading state machine bits ... Offloading and de-offloading RCU callback processes must be done carefully. There must never be a time at which callback processing is disabled because the task driving the offloading or de-offloading might be preempted or otherwise stalled at that point in time, which would result in OOM due to calbacks piling up indefinitely. This implies that there will be times during which a given CPU's callbacks might be concurrently invoked by both that CPU's RCU_SOFTIRQ handler (or, equivalently, that CPU's rcuc kthread) and by that CPU's rcuo kthread. This situation could fatally confuse both rcu_barrier() and the CPU-hotplug offlining process, so these must be excluded during any concurrent-callback-invocation period. In addition, during times of concurrent callback invocation, changes to ->cblist must be protected both as needed for RCU_SOFTIRQ and as needed for the rcuo kthread. This commit therefore defines and documents the states for a state machine that coordinates offloading and deoffloading. Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Neeraj Upadhyay <neeraju@codeaurora.org> Cc: Thomas Gleixner <tglx@linutronix.de> Inspired-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>		2021-01-06 16:24:19 -08:00
..
bpf	Merge branch 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	2020-12-15 19:29:43 -08:00
cgroup	Merge branch 'akpm' (patches from Andrew)	2020-12-15 12:53:37 -08:00
configs	Input: gtco - remove driver	2020-12-09 17:47:36 -08:00
debug	smp: Cleanup smp_call_function*()	2020-11-24 16:47:49 +01:00
dma	dma-mapping updates for 5.11:	2020-12-22 13:19:43 -08:00
entry	The new preemtible kmap_local() implementation:	2020-12-14 18:35:53 -08:00
events	Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	2020-12-15 19:36:48 -08:00
gcov	gcov: fix kernel-doc markup issue	2020-12-15 22:46:18 -08:00
irq	genirq: Fix export of irq_to_desc() for powerpc KVM	2020-12-25 11:02:39 -08:00
kcsan	kcsan: Fix encoding masks and regain address bit	2020-11-06 17:19:26 -08:00
livepatch	livepatch: Use the default ftrace_ops instead of REGS when ARGS is available	2020-11-13 12:15:28 -05:00
locking	A moderate set of locking updates:	2020-12-14 17:27:47 -08:00
power	Power management updates for 5.11-rc1	2020-12-15 16:30:31 -08:00
printk	printk changes for 5.11	2020-12-16 10:45:11 -08:00
rcu	rcu/nocb: Provide basic callback offloading state machine bits	2021-01-06 16:24:19 -08:00
sched	Fix a context switch performance regression.	2020-12-27 09:00:47 -08:00
time	Update/fix two CPU sanity checks in the hotplug and the boot code,	2020-12-27 09:03:41 -08:00
trace	Tracing updates for 5.11	2020-12-17 13:22:17 -08:00
.gitignore
acct.c	kernel/acct.c: use #elif instead of #end and #elif	2020-12-15 22:46:15 -08:00
async.c	treewide: Remove uninitialized_var() usage	2020-07-16 12:35:15 -07:00
audit.c	audit: replace atomic_add_return()	2020-12-02 22:52:16 -05:00
audit.h	audit: change unnecessary globals into statics	2020-08-17 20:26:58 -04:00
audit_fsnotify.c	fsnotify: generalize handle_inode_event()	2020-12-03 14:58:35 +01:00
audit_tree.c	fsnotify: generalize handle_inode_event()	2020-12-03 14:58:35 +01:00
audit_watch.c	fsnotify: generalize handle_inode_event()	2020-12-03 14:58:35 +01:00
auditfilter.c	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
auditsc.c	audit/stable-5.11 PR 20201214	2020-12-16 10:54:03 -08:00
backtracetest.c	treewide: Replace DECLARE_TASKLET() with DECLARE_TASKLET_OLD()	2020-07-30 11:15:58 -07:00
bounds.c
capability.c	LSM: Signal to SafeSetID when setting group IDs	2020-10-13 09:17:34 -07:00
compat.c	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
configs.c
context_tracking.c
cpu.c	Scheduler updates:	2020-12-14 18:29:11 -08:00
cpu_pm.c	notifier: Fix broken error handling pattern	2020-09-01 09:58:03 +02:00
crash_core.c	kdump: append uts_namespace.name offset to VMCOREINFO	2020-12-15 22:46:18 -08:00
crash_dump.c
cred.c
delayacct.c
dma.c
exec_domain.c
exit.c	Merge branch 'linus' into sched/core, to resolve semantic conflict	2020-11-27 11:10:50 +01:00
extable.c
fail_function.c	fault-injection: handle EI_ETYPE_TRUE	2020-12-15 22:46:19 -08:00
fork.c	kasan: rename (un)poison_shadow to (un)poison_range	2020-12-22 12:55:06 -08:00
freezer.c
futex.c	Merge branch 'locking/rwsem'	2020-12-09 17:08:45 +01:00
gen_kheaders.sh
groups.c	LSM: Signal to SafeSetID when setting group IDs	2020-10-13 09:17:34 -07:00
hung_task.c	kernel/hung_task.c: make type annotations consistent	2020-11-02 12:14:19 -08:00
iomem.c
irq_work.c	irq_work: Optimize irq_work_single()	2020-11-24 16:47:49 +01:00
jump_label.c	jump_label: Fix usage in module __init	2020-12-18 16:53:12 +01:00
kallsyms.c	treewide: Convert macro and uses of __section(foo) to __section("foo")	2020-10-25 14:51:49 -07:00
kcmp.c	Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	2020-12-15 19:36:48 -08:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c	kernel: make kcov_common_handle consider the current context	2020-11-02 18:00:20 -08:00
kexec.c	LSM: Introduce kernel_post_load_data() hook	2020-10-05 13:37:03 +02:00
kexec_core.c	crypto: sha - split sha.h into sha1.h and sha2.h	2020-11-20 14:45:33 +11:00
kexec_elf.c
kexec_file.c	crypto: sha - split sha.h into sha1.h and sha2.h	2020-11-20 14:45:33 +11:00
kexec_internal.h
kheaders.c
kmod.c	kmod: remove redundant "be an" in the comment	2020-08-12 10:58:01 -07:00
kprobes.c	Merge branch 'linus' into perf/kprobes	2020-11-07 13:18:49 +01:00
ksysfs.c
kthread.c	Merge branch 'akpm' (patches from Andrew)	2020-12-15 12:53:37 -08:00
latencytop.c
Makefile	kcov: don't instrument with UBSAN	2020-12-15 22:46:19 -08:00
module-internal.h
module.c	Modules updates for v5.11	2020-12-17 13:01:31 -08:00
module_signature.c
module_signing.c
notifier.c	notifier: Fix broken error handling pattern	2020-09-01 09:58:03 +02:00
nsproxy.c	fixes-v5.11	2020-12-14 16:40:27 -08:00
padata.c	padata: fix possible padata_works_lock deadlock	2020-09-04 17:51:55 +10:00
panic.c	panic: don't dump stack twice on warn	2020-11-14 11:26:04 -08:00
params.c	Modules updates for v5.11	2020-12-17 13:01:31 -08:00
pid.c	Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	2020-12-15 19:36:48 -08:00
pid_namespace.c	fixes-v5.11	2020-12-14 16:40:27 -08:00
profile.c
ptrace.c	Merge branch 'akpm' (patches from Andrew)	2020-12-15 12:53:37 -08:00
range.c	kernel.h: split out min()/max() et al. helpers	2020-10-16 11:11:19 -07:00
reboot.c	reboot: hide from sysfs not applicable settings	2020-12-15 22:46:19 -08:00
regset.c	regset: kill ->get()	2020-07-27 14:31:12 -04:00
relay.c	relay: allow the use of const callback structs	2020-12-15 22:46:18 -08:00
resource.c	kernel/resource.c: fix kernel-doc markups	2020-12-15 22:46:18 -08:00
resource_kunit.c	resource: provide meaningful MODULE_LICENSE() in test suite	2020-11-25 18:52:35 +01:00
rseq.c
scftorture.c	scftorture: Add full-test stutter capability	2020-11-06 17:13:56 -08:00
scs.c	scs: switch to vmapped shadow stacks	2020-12-01 10:30:28 +00:00
seccomp.c	seccomp updates for v5.11-rc1	2020-12-16 11:30:10 -08:00
signal.c	tif-task_work.arch-2020-12-14	2020-12-16 12:33:35 -08:00
smp.c	Merge branch 'linus' into sched/core, to resolve semantic conflict	2020-11-27 11:10:50 +01:00
smpboot.c
smpboot.h
softirq.c	Misc fixes/updates:	2020-12-27 09:06:10 -08:00
stackleak.c	stackleak: let stack_erasing_sysctl take a kernel pointer buffer	2020-09-19 13:13:39 -07:00
stacktrace.c	stacktrace: Remove reliable argument from arch_stack_walk() callback	2020-09-18 14:24:16 +01:00
static_call.c	static_call: Fix return type of static_call_init	2020-10-02 21:18:25 +02:00
stop_machine.c	Merge branch 'linus' into sched/core, to resolve semantic conflict	2020-11-27 11:10:50 +01:00
sys.c	kernel: Implement selective syscall userspace redirection	2020-12-02 15:07:56 +01:00
sys_ni.c	epoll: wire up syscall epoll_pwait2	2020-12-19 11:18:38 -08:00
sysctl-test.c
sysctl.c	rcu: Panic after fixed number of stalls	2020-11-19 19:37:16 -08:00
task_work.c	task_work: remove legacy TWA_SIGNAL path	2020-12-12 09:17:38 -07:00
taskstats.c	treewide: rename nla_strlcpy to nla_strscpy.	2020-11-16 08:08:54 -08:00
test_kprobes.c
torture.c	rcutorture: Make stutter_wait() caller restore priority	2020-11-06 17:13:54 -08:00
tracepoint.c	tracepoints: Migrate to use SYSCALL_WORK flag	2020-11-16 21:53:15 +01:00
tsacct.c
ucount.c
uid16.c
uid16.h
umh.c	usermodehelper: reset umask to default before executing user process	2020-10-06 10:31:52 -07:00
up.c
user-return-notifier.c
user.c	user: Use generic ns_common::count	2020-08-19 14:14:12 +02:00
user_namespace.c	fixes-v5.11	2020-12-14 16:40:27 -08:00
usermode_driver.c
utsname.c	uts: Use generic ns_common::count	2020-08-19 14:13:20 +02:00
utsname_sysctl.c
watch_queue.c	watch_queue: Limit the number of watches a user can hold	2020-08-17 09:39:18 -07:00
watchdog.c	kernel/watchdog: fix watchdog_allowed_mask not used warning	2020-11-14 11:26:03 -08:00
watchdog_hld.c
workqueue.c	Merge branch 'akpm' (patches from Andrew)	2020-12-15 12:53:37 -08:00
workqueue_internal.h