Re: [PATCH v5 tip/core/rcu 4/9] completion: Replace spin_unlock_wait() with lock/unlock pair

Paul E. McKenney
2017-08-17T15:32:44Z

On Thu, Aug 17, 2017 at 07:13:04AM -0700, Paul E. McKenney wrote:
> On Thu, Aug 17, 2017 at 02:49:09PM +0200, Ingo Molnar wrote:
> >
> > * Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
> >
> > > > this change - or can I pick this up into the scheduler tree?
> > >
> > > Timely question! ;-)
> > >
> > > My current plan is to send you a pull request like the following later
> > > today, Pacific Time (but rebased adding Steve Rostedt's Reviewed-by).
> > > This patch is on one of the branches, currently v4.13-rc2..93d8d7a12090
> > > ("arch: Remove spin_unlock_wait() arch-specific definitions") in my
> > > -rcu tree.
> > >
> > > Ah, and v4.13-rc2..7391304c4959 ("membarrier: Expedited private command")
> > > is mostly outside of RCU as well.
> > >
> > > Since I will be rebasing and remerging anyway, if you would prefer that I
> > > split the spin_unlock_wait() and/or misc branches out, I am happy to do so.
> > > If I don't hear otherwise, though, I will send all seven branches using
> > > my usual approach.
> > >
> > > So, if you want something different than my usual approach, please just
> > > let me know!
> >
> > No, all branches together sounds good to me!
>
> Very good, will do!
>
> > If you are rebasing anyway, here are some (very minor) commit title nits I noticed:
> >
> > > swait: add idle variants which don't contribute to load average
> > > rcu: use idle versions of swait to make idle-hack clear
> >
> > Capitalization.
>
> Will fix! Believe it or not, I looked for these... :-/
>
> > > membarrier: Expedited private command
> >
> > Should start with a verb.
>
> OK, something like "Provide expedited private command".
>
> > > doc: RCU documentation update
> >
> > doc: Update RCU documentation
> >
> > ?
>
> Works for me!
>
> > > doc: No longer allowed to use rcu_dereference on non-pointers
> >
> > doc: Describe that it is no longer allowed to use rcu_dereference() on non-pointers
> >
> > ?
>
> Will add a real commit log.
>
> > > torture: Add --kconfig argument to kvm.sh
> > > rcutorture: Don't wait for kernel when all builds fail
> >
> > Is there a difference between 'torture: ' and 'rcutorture: ' prefixes?
>
> Yes, rcutorture is specific to RCU, while torture would also affect
> locktorture.
>
> Ah, and if I am delaying the cond_resched() patch, I need to retest,
> which means I will send you the pull request tomorrow or Monday, depending
> on how the testing goes.

And here is the updated prototype pull request, FYI. Again, moving the
cond_resched() patch requires retesting, and if all goes well, I will
send you the official pull request tomorrow morning, Pacific Time.

Thanx, Paul

------------------------------------------------------------------------

The following changes since commit 520eccdfe187591a51ea9ab4c1a024ae4d0f68d9:

Linux 4.13-rc2 (2017-07-23 16:15:17 -0700)

are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git 656e7c0c0a2e8d899f87fd7f081ea7a711146604

for you to fetch changes up to 656e7c0c0a2e8d899f87fd7f081ea7a711146604:

Merge branches 'doc.2017.08.17a', 'fixes.2017.08.17a', 'hotplug.2017.07.25b', 'misc.2017.08.17a', 'spin_unlock_wait_no.2017.08.17a', 'srcu.2017.07.27c' and 'torture.2017.07.24c' into HEAD (2017-08-17 08:10:04 -0700)

----------------------------------------------------------------
Joe Perches (1):
module: Fix pr_fmt() bug for header use of printk

Luis R. Rodriguez (2):
swait: Add idle variants which don't contribute to load average
rcu: Use idle versions of swait to make idle-hack clear

Manfred Spraul (1):
net/netfilter/nf_conntrack_core: Fix net_conntrack_lock()

Masami Hiramatsu (1):
rcu/tracing: Set disable_rcu_irq_enter on rcu_eqs_exit()

Mathieu Desnoyers (1):
membarrier: Provide expedited private command

Oleg Nesterov (1):
task_work: Replace spin_unlock_wait() with lock/unlock pair

Paul E. McKenney (55):
documentation: Fix relation between nohz_full and rcu_nocbs
init_task: Remove redundant INIT_TASK_RCU_TREE_PREEMPT() macro
srcu: Move rcu_scheduler_starting() from Tiny RCU to Tiny SRCU
rcutorture: Remove obsolete SRCU-C.boot
srcu: Make process_srcu() be static
rcutorture: Move SRCU status printing to SRCU implementations
rcutorture: Print SRCU lock/unlock totals
rcu: Remove CONFIG_TASKS_RCU ifdef from rcuperf.c
rcutorture: Select CONFIG_PROVE_LOCKING for Tiny SRCU scenario
torture: Add --kconfig argument to kvm.sh
rcutorture: Don't wait for kernel when all builds fail
rcutorture: Enable SRCU readers from timer handler
rcutorture: Place event-traced strings into trace buffer
rcutorture: Use nr_cpus rather than maxcpus to limit test size
rcutorture: Add task's CPU for rcutorture writer stalls
rcutorture: Eliminate unused ts_rem local from rcu_trace_clock_local()
rcu: Add last-CPU to GP-kthread starvation messages
rcutorture: Invoke call_rcu() from timer handler
rcu: Use timer as backstop for NOCB deferred wakeups
atomics: Revert addition of comment header to spin_unlock_wait()
rcu: Migrate callbacks earlier in the CPU-offline timeline
rcu: Make expedited GPs correctly handle hardware CPU insertion
torture: Fix typo suppressing CPU-hotplug statistics
rcu: Remove orphan/adopt event-tracing fields
rcu: Check for NOCB CPUs and empty lists earlier in CB migration
rcu: Make NOCB CPUs migrate CBs directly from outgoing CPU
rcu: Advance outgoing CPU's callbacks before migrating them
rcu: Eliminate rcu_state ->orphan_lock
rcu: Advance callbacks after migration
rcu: Localize rcu_state ->orphan_pend and ->orphan_done
rcu: Remove unused RCU list functions
rcu: Move callback-list warning to irq-disable region
srcu: Provide ordering for CPU not involved in grace period
sched: Replace spin_unlock_wait() with lock/unlock pair
rcu: Drive TASKS_RCU directly off of PREEMPT
rcu: Create reasonable API for do_exit() TASKS_RCU processing
rcu: Add TPS() to event-traced strings
rcu: Move rcu.h to new trivial-function style
rcu: Add event tracing to ->gp_tasks update at GP start
rcu: Add TPS() protection for _rcu_barrier_trace strings
rcu: Add assertions verifying blocked-tasks list
rcu: Add warning to rcu_idle_enter() for irqs enabled
rcu: Remove exports from rcu_idle_exit() and rcu_idle_enter()
doc: Update RCU documentation
doc: Update memory-barriers.txt for read-to-write dependencies
doc: Add RCU files to docbook-generation files
doc: No longer allowed to use rcu_dereference on non-pointers
doc: Set down RCU's scheduling-clock-interrupt needs
completion: Replace spin_unlock_wait() with lock/unlock pair
exit: Replace spin_unlock_wait() with lock/unlock pair
ipc: Replace spin_unlock_wait() with lock/unlock pair
drivers/ata: Replace spin_unlock_wait() with lock/unlock pair
locking: Remove spin_unlock_wait() generic definitions
arch: Remove spin_unlock_wait() arch-specific definitions
Merge branches 'doc.2017.08.17a', 'fixes.2017.08.17a', 'hotplug.2017.07.25b', 'misc.2017.08.17a', 'spin_unlock_wait_no.2017.08.17a', 'srcu.2017.07.27c' and 'torture.2017.07.24c' into HEAD

Peter Zijlstra (Intel) (1):
rcu: Make rcu_idle_enter() rely on callers disabling irqs

Tejun Heo (1):
sched: Allow migrating kthreads into online but inactive CPUs

.../RCU/Design/Requirements/Requirements.html | 130 +++++++++++
Documentation/RCU/checklist.txt | 121 +++++++----
Documentation/RCU/rcu.txt | 9 +-
Documentation/RCU/rcu_dereference.txt | 61 ++----
Documentation/RCU/rcubarrier.txt | 5 +
Documentation/RCU/torture.txt | 20 +-
Documentation/RCU/whatisRCU.txt | 5 +-
Documentation/admin-guide/kernel-parameters.txt | 7 +-
Documentation/core-api/kernel-api.rst | 49 +++++
Documentation/memory-barriers.txt | 41 ++--
MAINTAINERS | 2 +-
arch/alpha/include/asm/spinlock.h | 5 -
arch/arc/include/asm/spinlock.h | 5 -
arch/arm/include/asm/spinlock.h | 16 --
arch/arm64/include/asm/spinlock.h | 58 +----
arch/arm64/kernel/process.c | 2 +
arch/blackfin/include/asm/spinlock.h | 5 -
arch/blackfin/kernel/module.c | 39 ++--
arch/hexagon/include/asm/spinlock.h | 5 -
arch/ia64/include/asm/spinlock.h | 21 --
arch/m32r/include/asm/spinlock.h | 5 -
arch/metag/include/asm/spinlock.h | 5 -
arch/mn10300/include/asm/spinlock.h | 5 -
arch/parisc/include/asm/spinlock.h | 7 -
arch/powerpc/include/asm/spinlock.h | 33 ---
arch/s390/include/asm/spinlock.h | 7 -
arch/sh/include/asm/spinlock-cas.h | 5 -
arch/sh/include/asm/spinlock-llsc.h | 5 -
arch/sparc/include/asm/spinlock_32.h | 5 -
arch/tile/include/asm/spinlock_32.h | 2 -
arch/tile/include/asm/spinlock_64.h | 2 -
arch/tile/lib/spinlock_32.c | 23 --
arch/tile/lib/spinlock_64.c | 22 --
arch/xtensa/include/asm/spinlock.h | 5 -
drivers/ata/libata-eh.c | 8 +-
include/asm-generic/qspinlock.h | 14 --
include/linux/init_task.h | 8 +-
include/linux/rcupdate.h | 15 +-
include/linux/rcutiny.h | 8 +-
include/linux/sched.h | 5 +-
include/linux/spinlock.h | 31 ---
include/linux/spinlock_up.h | 6 -
include/linux/srcutiny.h | 13 ++
include/linux/srcutree.h | 3 +-
include/linux/swait.h | 55 +++++
include/trace/events/rcu.h | 7 +-
include/uapi/linux/membarrier.h | 23 +-
ipc/sem.c | 3 +-
kernel/Makefile | 1 -
kernel/cpu.c | 1 +
kernel/exit.c | 10 +-
kernel/locking/qspinlock.c | 117 ----------
kernel/membarrier.c | 70 ------
kernel/rcu/Kconfig | 3 +-
kernel/rcu/rcu.h | 128 ++---------
kernel/rcu/rcu_segcblist.c | 108 +++-------
kernel/rcu/rcu_segcblist.h | 28 +--
kernel/rcu/rcuperf.c | 17 +-
kernel/rcu/rcutorture.c | 83 +++----
kernel/rcu/srcutiny.c | 8 +
kernel/rcu/srcutree.c | 50 ++++-
kernel/rcu/tiny.c | 2 -
kernel/rcu/tiny_plugin.h | 47 ----
kernel/rcu/tree.c | 213 ++++++++----------
kernel/rcu/tree.h | 15 +-
kernel/rcu/tree_exp.h | 2 +-
kernel/rcu/tree_plugin.h | 238 ++++++++++++---------
kernel/rcu/update.c | 18 +-
kernel/sched/Makefile | 1 +
kernel/sched/completion.c | 11 +-
kernel/sched/core.c | 38 +++-
kernel/sched/membarrier.c | 152 +++++++++++++
kernel/task_work.c | 8 +-
kernel/torture.c | 2 +-
net/netfilter/nf_conntrack_core.c | 52 +++--
.../selftests/rcutorture/bin/config_override.sh | 61 ++++++
.../testing/selftests/rcutorture/bin/functions.sh | 27 ++-
.../testing/selftests/rcutorture/bin/kvm-build.sh | 11 +-
.../selftests/rcutorture/bin/kvm-test-1-run.sh | 58 ++---
tools/testing/selftests/rcutorture/bin/kvm.sh | 34 ++-
.../selftests/rcutorture/configs/rcu/BUSTED.boot | 2 +-
.../selftests/rcutorture/configs/rcu/SRCU-C.boot | 1 -
.../selftests/rcutorture/configs/rcu/SRCU-u | 3 +-
.../selftests/rcutorture/configs/rcu/TREE01.boot | 2 +-
.../selftests/rcutorture/doc/TREE_RCU-kconfig.txt | 2 +-
85 files changed, 1237 insertions(+), 1323 deletions(-)
delete mode 100644 kernel/membarrier.c
delete mode 100644 kernel/rcu/tiny_plugin.h
create mode 100644 kernel/sched/membarrier.c
create mode 100755 tools/testing/selftests/rcutorture/bin/config_override.sh
delete mode 100644 tools/testing/selftests/rcutorture/configs/rcu/SRCU-C.boot