Anna-Maria Gleixner
f61eff83ce
hrtimer: Prepare support for PREEMPT_RT
...
When PREEMPT_RT is enabled, the soft interrupt thread can be preempted. If
the soft interrupt thread is preempted in the middle of a timer callback,
then calling hrtimer_cancel() can lead to two issues:
- If the caller is on a remote CPU then it has to spin wait for the timer
handler to complete. This can result in unbound priority inversion.
- If the caller originates from the task which preempted the timer
handler on the same CPU, then spin waiting for the timer handler to
complete is never going to end.
To avoid these issues, add a new lock to the timer base which is held
around the execution of the timer callbacks. If hrtimer_cancel() detects
that the timer callback is currently running, it blocks on the expiry
lock. When the callback is finished, the expiry lock is dropped by the
softirq thread which wakes up the waiter and the system makes progress.
This addresses both the priority inversion and the life lock issues.
The same issue can happen in virtual machines when the vCPU which runs a
timer callback is scheduled out. If a second vCPU of the same guest calls
hrtimer_cancel() it will spin wait for the other vCPU to be scheduled back
in. The expiry lock mechanism would avoid that. It'd be trivial to enable
this when paravirt spinlocks are enabled in a guest, but it's not clear
whether this is an actual problem in the wild, so for now it's an RT only
mechanism.
[ tglx: Refactored it for mainline ]
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185753.737767218@linutronix.de
2019-08-01 20:51:22 +02:00
..
bpf
Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2019-07-20 10:45:15 -07:00
cgroup
Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2019-07-19 10:42:02 -07:00
configs
debug
treewide: Add SPDX license identifier - Makefile/Kconfig
2019-05-21 10:50:46 +02:00
dma
dma-mapping fixes for 5.3-rc1
2019-07-20 12:09:52 -07:00
events
perf/core: Mark hrtimers to expire in hard interrupt context
2019-08-01 20:51:20 +02:00
gcov
gcov: no need to check return value of debugfs_create functions
2019-06-03 16:18:12 +02:00
irq
Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2019-07-08 11:22:57 -07:00
livepatch
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching
2019-07-11 15:30:05 -07:00
locking
docs: locking: convert docs to ReST and rename to *.rst
2019-07-15 08:53:27 -03:00
power
pci-v5.3-changes
2019-07-15 20:44:49 -07:00
printk
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13
2019-05-21 11:28:45 +02:00
rcu
Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
2019-06-28 19:46:47 +02:00
sched
sched: Mark hrtimers to expire in hard interrupt context
2019-08-01 20:51:19 +02:00
time
hrtimer: Prepare support for PREEMPT_RT
2019-08-01 20:51:22 +02:00
trace
Eiichi Tsukata found a small bug from the fixup of the stack code
2019-07-19 12:18:46 -07:00
.gitignore
Provide in-kernel headers to make extending kernel easier
2019-04-29 16:48:03 +02:00
acct.c
acct_on(): don't mess with freeze protection
2019-04-04 21:04:13 -04:00
async.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441
2019-06-05 17:37:17 +02:00
audit.c
audit/stable-5.3 PR 20190702
2019-07-08 18:55:42 -07:00
audit.h
audit/stable-5.3 PR 20190702
2019-07-08 18:55:42 -07:00
audit_fsnotify.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
2019-05-30 11:26:37 -07:00
audit_tree.c
fsnotify: switch send_to_group() and ->handle_event to const struct qstr *
2019-04-26 13:51:03 -04:00
audit_watch.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156
2019-05-30 11:26:35 -07:00
auditfilter.c
audit/stable-5.3 PR 20190702
2019-07-08 18:55:42 -07:00
auditsc.c
audit: enforce op for string fields
2019-05-28 17:46:43 -04:00
backtracetest.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441
2019-06-05 17:37:17 +02:00
bounds.c
capability.c
compat.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500
2019-06-19 17:09:55 +02:00
configs.c
kernel/configs: use .incbin directive to embed config_data.gz
2019-03-07 18:32:02 -08:00
context_tracking.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
cpu.c
Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2019-07-08 10:39:56 -07:00
cpu_pm.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282
2019-06-05 17:36:37 +02:00
crash_core.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 230
2019-06-19 17:09:06 +02:00
crash_dump.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
cred.c
request_key improvements
2019-07-08 19:19:37 -07:00
delayacct.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 25
2019-05-21 11:52:39 +02:00
dma.c
elfcore.c
exec_domain.c
exit.c
pidfd: fix a poll race when setting exit_state
2019-07-22 16:02:03 +02:00
extable.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156
2019-05-30 11:26:35 -07:00
fail_function.c
fail_function: no need to check return value of debugfs_create functions
2019-06-03 15:49:06 +02:00
fork.c
for-linus-20190715
2019-07-16 11:30:07 -07:00
freezer.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
futex.c
hrtimer/treewide: Use hrtimer_sleeper_start_expires()
2019-08-01 17:43:16 +02:00
gen_kheaders.sh
kheaders: include only headers into kheaders_data.tar.xz
2019-07-09 10:10:52 +09:00
groups.c
hung_task.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
iomem.c
mm/nvdimm: add is_ioremap_addr and use that to check ioremap address
2019-07-12 11:05:40 -07:00
irq_work.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
jump_label.c
jump_label: Batch updates if arch supports it
2019-06-17 12:09:22 +02:00
kallsyms.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
kcmp.c
Kconfig.freezer
treewide: Add SPDX license identifier - Makefile/Kconfig
2019-05-21 10:50:46 +02:00
Kconfig.hz
treewide: Add SPDX license identifier - Makefile/Kconfig
2019-05-21 10:50:46 +02:00
Kconfig.locks
treewide: Add SPDX license identifier - Makefile/Kconfig
2019-05-21 10:50:46 +02:00
Kconfig.preempt
sched/rt, Kconfig: Unbreak def/oldconfig with CONFIG_PREEMPT=y
2019-07-22 18:05:11 +02:00
kcov.c
kcov: convert kcov.refcount to refcount_t
2019-03-07 18:32:02 -08:00
kexec.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 230
2019-06-19 17:09:06 +02:00
kexec_core.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 230
2019-06-19 17:09:06 +02:00
kexec_file.c
Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity
2019-07-08 20:28:59 -07:00
kexec_internal.h
kheaders.c
kheaders: Move from proc to sysfs
2019-05-24 20:16:01 +02:00
kmod.c
kprobes.c
The main changes in this release include:
2019-07-18 11:51:00 -07:00
ksysfs.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 170
2019-05-30 11:26:39 -07:00
kthread.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
latencytop.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441
2019-06-05 17:37:17 +02:00
Makefile
kheaders: Move from proc to sysfs
2019-05-24 20:16:01 +02:00
memremap.c
mm/devm_memremap_pages: enable sub-section remap
2019-07-18 17:08:07 -07:00
module-internal.h
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36
2019-05-24 17:27:11 +02:00
module.c
Modules updates for v5.3
2019-07-18 12:06:57 -07:00
module_signing.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36
2019-05-24 17:27:11 +02:00
notifier.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
nsproxy.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441
2019-06-05 17:37:17 +02:00
padata.c
padata: use smp_mb in padata_reorder to avoid orphaned padata jobs
2019-07-18 13:39:54 +08:00
panic.c
docs: admin-guide: move sysctl directory to it
2019-07-15 11:03:01 -03:00
params.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156
2019-05-30 11:26:35 -07:00
pid.c
kernel/pid.c: convert struct pid count to refcount_t
2019-07-16 19:23:24 -07:00
pid_namespace.c
proc/sysctl: add shared variables for range check
2019-07-18 17:08:07 -07:00
profile.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
ptrace.c
ptrace: add PTRACE_GET_SYSCALL_INFO request
2019-07-16 19:23:24 -07:00
range.c
reboot.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
relay.c
Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2019-03-12 13:27:20 -07:00
resource.c
resource: avoid unnecessary lookups in find_next_iomem_res()
2019-07-18 17:08:06 -07:00
rseq.c
signal: Remove task parameter from force_sig
2019-05-27 09:36:28 -05:00
seccomp.c
signal: Remove the signal number and task parameters from force_sig_info
2019-05-29 09:31:44 -05:00
signal.c
signal: simplify set_user_sigmask/restore_user_sigmask
2019-07-16 19:23:24 -07:00
smp.c
smp: Warn on function calls from softirq context
2019-07-20 11:27:16 +02:00
smpboot.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
smpboot.h
softirq.c
Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2019-07-08 11:01:13 -07:00
stackleak.c
stacktrace.c
stacktrace: Force USER_DS for stack_trace_save_user()
2019-07-18 16:47:24 +02:00
stop_machine.c
processor: get rid of cpu_relax_yield
2019-06-15 12:25:55 +02:00
sys.c
prctl_set_mm: downgrade mmap_sem to read lock
2019-06-01 15:51:31 -07:00
sys_ni.c
arch: handle arches who do not yet define clone3
2019-06-21 01:54:53 +02:00
sysctl.c
proc/sysctl: add shared variables for range check
2019-07-18 17:08:07 -07:00
sysctl_binary.c
task_work.c
taskstats.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
2019-05-30 11:26:37 -07:00
test_kprobes.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 25
2019-05-21 11:52:39 +02:00
torture.c
torture: Allow inter-stutter interval to be specified
2019-05-28 09:06:09 -07:00
tracepoint.c
The main changes in this release include:
2019-07-18 11:51:00 -07:00
tsacct.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
2019-05-30 11:26:37 -07:00
ucount.c
proc/sysctl: add shared variables for range check
2019-07-18 17:08:07 -07:00
uid16.c
uid16.h
umh.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
up.c
smp: Remove smp_call_function() and on_each_cpu() return values
2019-06-23 14:26:26 +02:00
user-return-notifier.c
treewide: Add SPDX license identifier for missed files
2019-05-21 10:50:45 +02:00
user.c
Keyrings namespacing
2019-07-08 19:36:47 -07:00
user_namespace.c
Keyrings namespacing
2019-07-08 19:36:47 -07:00
utsname.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441
2019-06-05 17:37:17 +02:00
utsname_sysctl.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441
2019-06-05 17:37:17 +02:00
watchdog.c
watchdog: Mark watchdog_hrtimer to expire in hard interrupt context
2019-08-01 20:51:20 +02:00
watchdog_hld.c
kernel/watchdog_hld.c: hard lockup message should end with a newline
2019-04-19 09:46:05 -07:00
workqueue.c
workqueue: Remove GPF argument from alloc_workqueue_attrs()
2019-06-27 14:12:19 -07:00
workqueue_internal.h
sched/core, workqueues: Distangle worker accounting from rq lock
2019-04-16 16:55:15 +02:00