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724a86881d
linux/kernel
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Peter Zijlstra 724a86881d smp/hotplug: Callback vs state-machine consistency 
While the generic callback functions have an 'int' return and thus
appear to be allowed to return error, this is not true for all states.

Specifically, what used to be STARTING/DYING are ran with IRQs
disabled from critical parts of CPU bringup/teardown and are not
allowed to fail. Add WARNs to enforce this rule.

But since some callbacks are indeed allowed to fail, we have the
situation where a state-machine rollback encounters a failure, in this
case we're stuck, we can't go forward and we can't go back. Also add a
WARN for that case.

AFAICT this is a fundamental 'problem' with no real obvious solution.
We want the 'prepare' callbacks to allow failure on either up or down.
Typically on prepare-up this would be things like -ENOMEM from
resource allocations, and the typical usage in prepare-down would be
something like -EBUSY to avoid CPUs being taken away.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: bigeasy@linutronix.de
Cc: efault@gmx.de
Cc: rostedt@goodmis.org
Cc: max.byungchul.park@gmail.com
Link: https://lkml.kernel.org/r/20170920170546.819539119@infradead.org
2017-09-25 22:11:43 +02:00
..
bpf bpf: fix ri->map_owner pointer on bpf_prog_realloc 2017-09-19 16:38:53 -07:00
cgroup Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-12 11:30:56 -07:00
configs ANDROID: binder: add hwbinder,vndbinder to BINDER_DEVICES. 2017-08-22 18:43:23 -07:00
debug sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
events bpf: one perf event close won't free bpf program attached by another perf event 2017-09-20 14:10:29 -07:00
gcov gcov: support GCC 7.1 2017-05-12 15:57:15 -07:00
irq genirq: Fix cpumask check in __irq_startup_managed() 2017-09-16 20:20:56 +02:00
livepatch livepatch: Fix stacking of patches with respect to RCU 2017-06-20 10:42:19 +02:00
locking mm: treewide: remove GFP_TEMPORARY allocation flag 2017-09-13 18:53:16 -07:00
power Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-12 11:30:56 -07:00
printk Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk 2017-09-07 21:00:52 -07:00
rcu treewide: make "nr_cpu_ids" unsigned 2017-09-08 18:26:48 -07:00
sched sched/wait: Introduce wakeup boomark in wake_up_page_bit 2017-09-14 09:56:18 -07:00
time drivers/pps: aesthetic tweaks to PPS-related content 2017-09-08 18:26:51 -07:00
trace This includes 3 minor fixes. 2017-09-20 06:38:07 -10:00
.gitignore
acct.c fs: make the buf argument to __kernel_write a void pointer 2017-09-04 19:05:15 -04:00
async.c async: Adjust system_state checks 2017-05-23 10:01:37 +02:00
audit_fsnotify.c Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2017-05-03 11:05:15 -07:00
audit_tree.c Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2017-05-03 11:05:15 -07:00
audit_watch.c audit/stable-4.13 PR 20170816 2017-08-16 16:48:34 -07:00
audit.c audit: update the function comments 2017-09-05 09:46:59 -04:00
audit.h ipc: mqueue: Replace timespec with timespec64 2017-09-03 20:21:24 -04:00
auditfilter.c audit: kernel generated netlink traffic should have a portid of 0 2017-05-02 10:16:05 -04:00
auditsc.c Merge branch 'work.ipc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-09-14 17:37:26 -07:00
backtracetest.c
bounds.c
capability.c
compat.c semtimedop(): move compat to native 2017-07-15 20:46:47 -04:00
configs.c
context_tracking.c
cpu_pm.c PM / CPU: replace raw_notifier with atomic_notifier 2017-07-31 13:09:49 +02:00
cpu.c smp/hotplug: Callback vs state-machine consistency 2017-09-25 22:11:43 +02:00
crash_core.c kdump: protect vmcoreinfo data under the crash memory 2017-07-12 16:26:00 -07:00
crash_dump.c
cred.c doc: ReSTify credentials.txt 2017-05-18 10:30:19 -06:00
delayacct.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
dma.c
elfcore.c
exec_domain.c
exit.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-09-11 18:34:47 -07:00
extable.c lib/extable.c: use bsearch() library function in search_extable() 2017-07-10 16:32:35 -07:00
fork.c selinux/stable-4.14 PR 20170831 2017-09-12 13:21:00 -07:00
freezer.c
futex_compat.c
futex.c futex: Remove duplicated code and fix undefined behaviour 2017-08-25 22:49:59 +02:00
groups.c kernel/groups.c: use sort library function 2017-07-10 16:32:34 -07:00
hung_task.c kernel/hung_task.c: defer showing held locks 2017-05-08 17:15:10 -07:00
irq_work.c
jump_label.c jump_label: Provide hotplug context variants 2017-08-10 12:28:59 +02:00
kallsyms.c kernel/kallsyms.c: replace all_var with IS_ENABLED(CONFIG_KALLSYMS_ALL) 2017-07-10 16:32:34 -07:00
kcmp.c kcmp: add KCMP_EPOLL_TFD mode to compare epoll target files 2017-07-12 16:26:01 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c kcov: support compat processes 2017-09-08 18:26:51 -07:00
kexec_core.c x86/mm, kexec: Allow kexec to be used with SME 2017-07-18 11:38:04 +02:00
kexec_file.c kexec_file: adjust declaration of kexec_purgatory 2017-07-12 16:26:02 -07:00
kexec_internal.h kexec_file: adjust declaration of kexec_purgatory 2017-07-12 16:26:02 -07:00
kexec.c kdump: protect vmcoreinfo data under the crash memory 2017-07-12 16:26:00 -07:00
kmod.c kmod: move #ifdef CONFIG_MODULES wrapper to Makefile 2017-09-08 18:26:51 -07:00
kprobes.c kprobes: Ensure that jprobe probepoints are at function entry 2017-07-08 11:05:35 +02:00
ksysfs.c kexec: move vmcoreinfo out of the kernel's .bss section 2017-07-12 16:25:59 -07:00
kthread.c kernel/kthread.c: kthread_worker: don't hog the cpu 2017-08-31 16:33:15 -07:00
latencytop.c sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h> 2017-03-02 08:42:39 +01:00
Makefile kmod: move #ifdef CONFIG_MODULES wrapper to Makefile 2017-09-08 18:26:51 -07:00
memremap.c mm/device-public-memory: device memory cache coherent with CPU 2017-09-08 18:26:46 -07:00
module_signing.c
module-internal.h
module.c module: fix ddebug_remove_module() 2017-07-25 15:08:32 +02:00
notifier.c kernel/notifier.c: simplify expression 2017-02-24 17:46:56 -08:00
nsproxy.c perf: Add PERF_RECORD_NAMESPACES to include namespaces related info 2017-03-13 15:57:41 -03:00
padata.c padata: Avoid nested calls to cpus_read_lock() in pcrypt_init_padata() 2017-05-26 10:10:37 +02:00
panic.c locking/refcounts, x86/asm: Implement fast refcount overflow protection 2017-08-17 10:40:26 +02:00
params.c boot/param: Move next_arg() function to lib/cmdline.c for later reuse 2017-04-18 10:37:13 +02:00
pid_namespace.c userns,pidns: Verify the userns for new pid namespaces 2017-07-20 07:43:58 -05:00
pid.c pids: make task_tgid_nr_ns() safe 2017-08-21 12:47:31 -07:00
profile.c sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h> 2017-03-02 08:42:39 +01:00
ptrace.c signal: Remove kernel interal si_code magic 2017-07-24 14:30:28 -05:00
range.c
reboot.c
relay.c Merge branch 'work.splice' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-02 11:38:06 -07:00
resource.c
seccomp.c seccomp: Implement SECCOMP_RET_KILL_PROCESS action 2017-08-14 13:46:50 -07:00
signal.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-09-11 18:34:47 -07:00
smp.c treewide: make "nr_cpu_ids" unsigned 2017-09-08 18:26:48 -07:00
smpboot.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
smpboot.h
softirq.c sched/core: Remove 'task' parameter and rename tsk_restore_flags() to current_restore_flags() 2017-04-11 09:06:32 +02:00
stacktrace.c stacktrace/x86: add function for detecting reliable stack traces 2017-03-08 09:18:02 +01:00
stop_machine.c stop_machine: Provide stop_machine_cpuslocked() 2017-05-26 10:10:36 +02:00
sys_ni.c
sys.c prctl: Allow local CAP_SYS_ADMIN changing exe_file 2017-07-20 07:46:07 -05:00
sysctl_binary.c fs: fix kernel_write prototype 2017-09-04 19:05:15 -04:00
sysctl.c kernel/watchdog: split up config options 2017-07-12 16:26:02 -07:00
task_work.c task_work: Replace spin_unlock_wait() with lock/unlock pair 2017-07-25 10:08:58 -07:00
taskstats.c taskstats: add e/u/stime for TGID command 2017-05-08 17:15:12 -07:00
test_kprobes.c
torture.c torture: Fix typo suppressing CPU-hotplug statistics 2017-07-25 13:04:45 -07:00
tracepoint.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
tsacct.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
ucount.c ucount: Remove the atomicity from ucount->count 2017-03-06 15:26:37 -06:00
uid16.c sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
umh.c kmod: split out umh code into its own file 2017-09-08 18:26:50 -07:00
up.c smp: Avoid using two cache lines for struct call_single_data 2017-08-29 15:14:38 +02:00
user_namespace.c userns,pidns: Verify the userns for new pid namespaces 2017-07-20 07:43:58 -05:00
user-return-notifier.c
user.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/user.h> 2017-03-02 08:42:29 +01:00
utsname_sysctl.c sched/headers: Remove <linux/rwsem.h> from <linux/sched.h> 2017-03-03 01:45:36 +01:00
utsname.c sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h> 2017-03-02 08:42:38 +01:00
watchdog_hld.c kernel/watchdog: Prevent false positives with turbo modes 2017-08-18 12:35:02 +02:00
watchdog.c kernel/watchdog: Prevent false positives with turbo modes 2017-08-18 12:35:02 +02:00
workqueue_internal.h
workqueue.c Merge branch 'for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2017-09-06 21:59:31 -07:00