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dd04140531
linux/kernel
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Paul E. McKenney dd04140531 rcu: Make polled grace-period API account for expedited grace periods 
Currently, this code could splat:

	oldstate = get_state_synchronize_rcu();
	synchronize_rcu_expedited();
	WARN_ON_ONCE(!poll_state_synchronize_rcu(oldstate));

This situation is counter-intuitive and user-unfriendly.  After all, there
really was a perfectly valid full grace period right after the call to
get_state_synchronize_rcu(), so why shouldn't poll_state_synchronize_rcu()
know about it?

This commit therefore makes the polled grace-period API aware of expedited
grace periods in addition to the normal grace periods that it is already
aware of.  With this change, the above code is guaranteed not to splat.

Please note that the above code can still splat due to counter wrap on the
one hand and situations involving partially overlapping normal/expedited
grace periods on the other.  On 64-bit systems, the second is of course
much more likely than the first.  It is possible to modify this approach
to prevent overlapping grace periods from causing splats, but only at
the expense of greatly increasing the probability of counter wrap, as
in within milliseconds on 32-bit systems and within minutes on 64-bit
systems.

This commit is in preparation for polled expedited grace periods.

Link: https://lore.kernel.org/all/20220121142454.1994916-1-bfoster@redhat.com/
Link: https://docs.google.com/document/d/1RNKWW9jQyfjxw2E8dsXVTdvZYh0HnYeSHDKog9jhdN8/edit?usp=sharing
Cc: Brian Foster <bfoster@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-07-21 17:41:56 -07:00
..
bpf bpf: Fix calling global functions from BPF_PROG_TYPE_EXT programs 2022-06-07 10:41:20 -07:00
cgroup Merge branch 'for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2022-05-25 11:47:25 -07:00
configs x86/configs: Add x86 debugging Kconfig fragment plus docs 2022-04-06 19:56:29 +02:00
debug Modules updates for v5.19-rc1 2022-05-26 17:13:43 -07:00
dma swiotlb: fix setting ->force_bounce 2022-06-02 07:17:59 +02:00
entry * Fix syzkaller NULL pointer dereference 2022-06-08 09:16:31 -07:00
events Two small perf updates: 2022-06-05 10:40:31 -07:00
futex drm for 5.19-rc1 2022-05-25 16:18:27 -07:00
gcov gcov: Remove compiler version check 2021-12-02 17:25:21 +09:00
irq genirq: PM: Use runtime PM for chained interrupts 2022-06-09 15:58:13 +01:00
kcsan linux-kselftest-kunit-5.19-rc1 2022-05-25 11:32:53 -07:00
livepatch Livepatching changes for 5.19 2022-06-02 08:55:01 -07:00
locking locking/lockdep: Use sched_clock() for random numbers 2022-06-13 10:29:57 +02:00
module module: Fix prefix for module.sig_enforce module param 2022-06-02 12:44:33 -07:00
power cxl for 5.19 2022-05-27 21:24:19 -07:00
printk printk: Wait for the global console lock when the system is going down 2022-06-15 22:04:15 +02:00
rcu rcu: Make polled grace-period API account for expedited grace periods 2022-07-21 17:41:56 -07:00
sched sched: Fix balance_push() vs __sched_setscheduler() 2022-06-13 10:15:07 +02:00
time While looking at the ptrace problems with PREEMPT_RT and the problems 2022-06-03 16:13:25 -07:00
trace Networking fixes for 5.19-rc2, including fixes from bpf and netfilter. 2022-06-09 12:06:52 -07:00
.gitignore
acct.c kernel/acct: move acct sysctls to its own file 2022-04-06 13:43:44 -07:00
async.c Revert "module, async: async_synchronize_full() on module init iff async is used" 2022-02-03 11:20:34 -08:00
audit_fsnotify.c fsnotify: make allow_dups a property of the group 2022-04-25 14:37:18 +02:00
audit_tree.c audit: use fsnotify group lock helpers 2022-04-25 14:37:28 +02:00
audit_watch.c fsnotify: pass flags argument to fsnotify_alloc_group() 2022-04-25 14:37:12 +02:00
audit.c audit: improve audit queue handling when "audit=1" on cmdline 2022-01-25 13:22:51 -05:00
audit.h audit: log AUDIT_TIME_* records only from rules 2022-02-22 13:51:40 -05:00
auditfilter.c audit/stable-5.17 PR 20220110 2022-01-11 13:08:21 -08:00
auditsc.c audit: free module name 2022-06-15 19:28:44 -04:00
backtracetest.c
bounds.c
capability.c xfs: don't generate selinux audit messages for capability testing 2022-03-09 10:32:06 -08:00
cfi.c cfi: Fix __cfi_slowpath_diag RCU usage with cpuidle 2022-06-13 09:18:46 -07:00
compat.c
configs.c
context_tracking.c
cpu_pm.c
cpu.c Intel Trust Domain Extensions 2022-05-23 17:51:12 -07:00
crash_core.c Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
crash_dump.c
cred.c x86: Mark __invalid_creds() __noreturn 2022-03-15 10:32:44 +01:00
delayacct.c delayacct: track delays from write-protect copy 2022-06-01 15:55:25 -07:00
dma.c
exec_domain.c
exit.c ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
extable.c lkdtm: Really write into kernel text in WRITE_KERN 2022-02-16 23:25:12 +11:00
fail_function.c
fork.c This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
freezer.c
gen_kheaders.sh kheaders: Have cpio unconditionally replace files 2022-05-08 03:16:59 +09:00
groups.c
hung_task.c Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
iomem.c
irq_work.c irq_work: use kasan_record_aux_stack_noalloc() record callstack 2022-04-15 14:49:55 -07:00
jump_label.c
kallsyms.c ftrace: Add ftrace_lookup_symbols function 2022-05-10 14:42:06 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels" 2022-03-31 10:36:55 +02:00
kcov.c kcov: update pos before writing pc in trace function 2022-05-25 13:05:42 -07:00
kexec_core.c Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
kexec_elf.c
kexec_file.c RISC-V Patches for the 5.19 Merge Window, Part 1 2022-05-31 14:10:54 -07:00
kexec_internal.h
kexec.c
kheaders.c
kmod.c
kprobes.c tracing updates for 5.19: 2022-05-29 10:31:36 -07:00
ksysfs.c kernel/ksysfs.c: use helper macro __ATTR_RW 2022-03-23 19:00:33 -07:00
kthread.c kthread: unexport kthread_blkcg 2022-05-02 14:06:20 -06:00
latencytop.c latencytop: move sysctl to its own file 2022-04-21 11:40:59 -07:00
Makefile kernel: add platform_has() infrastructure 2022-06-06 08:06:00 +02:00
module_signature.c
notifier.c notifier: Add blocking/atomic_notifier_chain_register_unique_prio() 2022-05-19 19:30:30 +02:00
nsproxy.c
padata.c padata: replace cpumask_weight with cpumask_empty in padata.c 2022-01-31 11:21:46 +11:00
panic.c Merge branch 'rework/kthreads' into for-linus 2022-06-17 16:36:48 +02:00
params.c kobject: remove kset from struct kset_uevent_ops callbacks 2021-12-28 11:26:18 +01:00
pid_namespace.c kernel: pid_namespace: use NULL instead of using plain integer as pointer 2022-04-29 14:38:00 -07:00
pid.c
platform-feature.c kernel: add platform_has() infrastructure 2022-06-06 08:06:00 +02:00
profile.c exit: Remove profile_handoff_task 2022-01-08 12:43:57 -06:00
ptrace.c While looking at the ptrace problems with PREEMPT_RT and the problems 2022-06-03 16:13:25 -07:00
range.c
reboot.c printk fixes for 5.19-rc3 2022-06-17 14:57:42 -05:00
regset.c
relay.c relay: remove redundant assignment to pointer buf 2022-05-12 20:38:37 -07:00
resource_kunit.c
resource.c kernel/resource: fix kfree() of bootmem memory again 2022-03-23 19:00:35 -07:00
rseq.c rseq: Remove broken uapi field layout on 32-bit little endian 2022-02-02 13:11:34 +01:00
scftorture.c scftorture: Fix distribution of short handler delays 2022-04-11 17:07:29 -07:00
scs.c kasan, vmalloc: only tag normal vmalloc allocations 2022-03-24 19:06:48 -07:00
seccomp.c seccomp: Add wait_killable semantic to seccomp user notifier 2022-05-03 14:11:58 -07:00
signal.c While looking at the ptrace problems with PREEMPT_RT and the problems 2022-06-03 16:13:25 -07:00
smp.c Scheduler changes in this cycle were: 2022-05-24 11:11:13 -07:00
smpboot.c cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again. 2022-04-12 14:13:01 +02:00
smpboot.h
softirq.c smp: Make softirq handling RT safe in flush_smp_call_function_queue() 2022-05-01 10:03:43 +02:00
stackleak.c stackleak: add on/off stack variants 2022-05-08 01:33:09 -07:00
stacktrace.c uaccess: remove CONFIG_SET_FS 2022-02-25 09:36:06 +01:00
static_call_inline.c static_call: Don't make __static_call_return0 static 2022-04-05 09:59:38 +02:00
static_call.c static_call: Don't make __static_call_return0 static 2022-04-05 09:59:38 +02:00
stop_machine.c Scheduler changes in this cycle were: 2022-05-24 11:11:13 -07:00
sys_ni.c mm/mempolicy: wire up syscall set_mempolicy_home_node 2022-01-15 16:30:30 +02:00
sys.c arm64/sme: Implement vector length configuration prctl()s 2022-04-22 18:50:54 +01:00
sysctl-test.c
sysctl.c sysctl changes for v5.19-rc1 2022-05-26 16:57:20 -07:00
task_work.c task_work: allow TWA_SIGNAL without a rescheduling IPI 2022-04-30 08:39:32 -06:00
taskstats.c kernel: make taskstats available from all net namespaces 2022-04-29 14:38:03 -07:00
torture.c torture: Wake up kthreads after storing task_struct pointer 2022-02-01 17:24:39 -08:00
tracepoint.c
tsacct.c taskstats: version 12 with thread group and exe info 2022-04-29 14:38:03 -07:00
ucount.c ucounts: Handle wrapping in is_ucounts_overlimit 2022-02-17 09:11:57 -06:00
uid16.c
uid16.h
umh.c kthread: Don't allocate kthread_struct for init and umh 2022-05-06 14:49:44 -05:00
up.c
user_namespace.c ucounts: Fix systemd LimitNPROC with private users regression 2022-02-25 10:40:14 -06:00
user-return-notifier.c
user.c
usermode_driver.c blob_to_mnt(): kern_unmount() is needed to undo kern_mount() 2022-05-19 23:25:47 -04:00
utsname_sysctl.c
utsname.c
watch_queue.c watch_queue: Free the page array when watch_queue is dismantled 2022-04-02 10:37:39 -07:00
watchdog_hld.c printk: add functions to prefer direct printing 2022-04-22 21:30:58 +02:00
watchdog.c Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
workqueue_internal.h
workqueue.c workqueue: Wrap flush_workqueue() using a macro 2022-06-07 07:07:14 -10:00