Commit Graph

1148 Commits

Author SHA1 Message Date
Linus Torvalds 203b6609e0 Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates from Ingo Molnar:
 "Lots of tooling updates - too many to list, here's a few highlights:

   - Various subcommand updates to 'perf trace', 'perf report', 'perf
     record', 'perf annotate', 'perf script', 'perf test', etc.

   - CPU and NUMA topology and affinity handling improvements,

   - HW tracing and HW support updates:
      - Intel PT updates
      - ARM CoreSight updates
      - vendor HW event updates

   - BPF updates

   - Tons of infrastructure updates, both on the build system and the
     library support side

   - Documentation updates.

   - ... and lots of other changes, see the changelog for details.

  Kernel side updates:

   - Tighten up kprobes blacklist handling, reduce the number of places
     where developers can install a kprobe and hang/crash the system.

   - Fix/enhance vma address filter handling.

   - Various PMU driver updates, small fixes and additions.

   - refcount_t conversions

   - BPF updates

   - error code propagation enhancements

   - misc other changes"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (238 commits)
  perf script python: Add Python3 support to syscall-counts-by-pid.py
  perf script python: Add Python3 support to syscall-counts.py
  perf script python: Add Python3 support to stat-cpi.py
  perf script python: Add Python3 support to stackcollapse.py
  perf script python: Add Python3 support to sctop.py
  perf script python: Add Python3 support to powerpc-hcalls.py
  perf script python: Add Python3 support to net_dropmonitor.py
  perf script python: Add Python3 support to mem-phys-addr.py
  perf script python: Add Python3 support to failed-syscalls-by-pid.py
  perf script python: Add Python3 support to netdev-times.py
  perf tools: Add perf_exe() helper to find perf binary
  perf script: Handle missing fields with -F +..
  perf data: Add perf_data__open_dir_data function
  perf data: Add perf_data__(create_dir|close_dir) functions
  perf data: Fail check_backup in case of error
  perf data: Make check_backup work over directories
  perf tools: Add rm_rf_perf_data function
  perf tools: Add pattern name checking to rm_rf
  perf tools: Add depth checking to rm_rf
  perf data: Add global path holder
  ...
2019-03-06 07:59:36 -08:00
Linus Torvalds 3717f613f4 Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:
 "The main RCU related changes in this cycle were:

   - Additional cleanups after RCU flavor consolidation

   - Grace-period forward-progress cleanups and improvements

   - Documentation updates

   - Miscellaneous fixes

   - spin_is_locked() conversions to lockdep

   - SPDX changes to RCU source and header files

   - SRCU updates

   - Torture-test updates, including nolibc updates and moving nolibc to
     tools/include"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (71 commits)
  locking/locktorture: Convert to SPDX license identifier
  linux/torture: Convert to SPDX license identifier
  torture: Convert to SPDX license identifier
  linux/srcu: Convert to SPDX license identifier
  linux/rcutree: Convert to SPDX license identifier
  linux/rcutiny: Convert to SPDX license identifier
  linux/rcu_sync: Convert to SPDX license identifier
  linux/rcu_segcblist: Convert to SPDX license identifier
  linux/rcupdate: Convert to SPDX license identifier
  linux/rcu_node_tree: Convert to SPDX license identifier
  rcu/update: Convert to SPDX license identifier
  rcu/tree: Convert to SPDX license identifier
  rcu/tiny: Convert to SPDX license identifier
  rcu/sync: Convert to SPDX license identifier
  rcu/srcu: Convert to SPDX license identifier
  rcu/rcutorture: Convert to SPDX license identifier
  rcu/rcu_segcblist: Convert to SPDX license identifier
  rcu/rcuperf: Convert to SPDX license identifier
  rcu/rcu.h: Convert to SPDX license identifier
  RCU/torture.txt: Remove section MODULE PARAMETERS
  ...
2019-03-05 14:49:11 -08:00
Masami Hiramatsu a39f15b964 kprobes: Prohibit probing on RCU debug routine
Since kprobe itself depends on RCU, probing on RCU debug
routine can cause recursive breakpoint bugs.

Prohibit probing on RCU debug routines.

int3
 ->do_int3()
   ->ist_enter()
     ->RCU_LOCKDEP_WARN()
       ->debug_lockdep_rcu_enabled() -> int3

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrea Righi <righi.andrea@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/154998807741.31052.11229157537816341591.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-13 08:16:40 +01:00
Masami Hiramatsu c13324a505 x86/kprobes: Prohibit probing on functions before kprobe_int3_handler()
Prohibit probing on the functions called before kprobe_int3_handler()
in do_int3(). More specifically, ftrace_int3_handler(),
poke_int3_handler(), and ist_enter(). And since rcu_nmi_enter() is
called by ist_enter(), it also should be marked as NOKPROBE_SYMBOL.

Since those are handled before kprobe_int3_handler(), probing those
functions can cause a breakpoint recursion and crash the kernel.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrea Righi <righi.andrea@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/154998793571.31052.11301258949601150994.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-13 08:16:39 +01:00
Paul E. McKenney e7ffb4eb9a Merge branches 'doc.2019.01.26a', 'fixes.2019.01.26a', 'sil.2019.01.26a', 'spdx.2019.02.09a', 'srcu.2019.01.26a' and 'torture.2019.01.26a' into HEAD
doc.2019.01.26a:  Documentation updates.
fixes.2019.01.26a:  Miscellaneous fixes.
sil.2019.01.26a:  Removal of a few more spin_is_locked() instances.
spdx.2019.02.09a:  Add SPDX identifiers to RCU files
srcu.2019.01.26a:  SRCU updates.
torture.2019.01.26a: Torture-test updates.
2019-02-09 08:47:52 -08:00
Paul E. McKenney 38b4df649e rcu/update: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09 08:44:27 -08:00
Paul E. McKenney 22e4092531 rcu/tree: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Update .h file SPDX comment format per Joe Perches. ]
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09 08:44:10 -08:00
Paul E. McKenney 00de9d7415 rcu/tiny: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09 08:44:05 -08:00
Paul E. McKenney 96b903f5da rcu/sync: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09 08:43:59 -08:00
Paul E. McKenney e7ee1501cd rcu/srcu: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09 08:43:54 -08:00
Paul E. McKenney 2e24ce8852 rcu/rcutorture: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09 08:43:46 -08:00
Paul E. McKenney eb7935e479 rcu/rcu_segcblist: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09 08:43:40 -08:00
Paul E. McKenney 8bf05ed3ad rcu/rcuperf: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09 08:43:35 -08:00
Paul E. McKenney b5b11890de rcu/rcu.h: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09 08:43:05 -08:00
Paul E. McKenney e838a7d66e rcuperf: Stop abusing IS_ENABLED()
The ever-evolving IS_ENABLED() macro is intended for CONFIG_* Kconfig
options, but rcuperf currently uses it for the decidedly non-CONFIG_*
MODULE macro.  In the spirit of not inviting trouble, this commit
substitutes tried-and-true #ifdef.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
2019-01-25 15:37:11 -08:00
Paul E. McKenney 3a6cb58f15 rcutorture: Add grace period after CPU offline
Beyond a certain point in the CPU-hotplug offline process, timers get
stranded on the outgoing CPU, and won't fire until that CPU comes back
online, which might well be never.  This commit therefore adds a hook
in torture_onoff_init() that is invoked from torture_offline(), which
rcutorture uses to occasionally wait for a grace period.  This should
result in failures for RCU implementations that rely on stranded timers
eventually firing in the absence of the CPU coming back online.

Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:37:10 -08:00
Paul E. McKenney cd618d102b rcutorture: Record grace periods in forward-progress histogram
This commit records grace periods in rcutorture's n_launders_hist[]
histogram, thus allowing rcu_torture_fwd_cb_hist() to print out the
elapsed number of grace periods between buckets.  This information
helps to determine whether a lack of forward progress is due to stalled
grace periods on the one hand or due to sluggish callback invocation on
the other.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:37:09 -08:00
Sebastian Andrzej Siewior e81baf4cb1 srcu: Remove srcu_queue_delayed_work_on()
srcu_queue_delayed_work_on() disables preemption (and therefore CPU
hotplug in RCU's case) and then checks based on its own accounting if a
CPU is online. If the CPU is online it uses queue_delayed_work_on()
otherwise it fallbacks to queue_delayed_work().
The problem here is that queue_work() on -RT does not work with disabled
preemption.

queue_work_on() works also on an offlined CPU. queue_delayed_work_on()
has the problem that it is possible to program a timer on an offlined
CPU. This timer will fire once the CPU is online again. But until then,
the timer remains programmed and nothing will happen.

Add a local timer which will fire (as requested per delay) on the local
CPU and then enqueue the work on the specific CPU.

RCUtorture testing with SRCU-P for 24h showed no problems.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:36:42 -08:00
Paul E. McKenney c2d8089de7 rcu: Fix obsolete DYNTICK_IRQ_NONIDLE comment
This commit updates the DYNTICK_IRQ_NONIDLE header comment to remove
the obsolete commentary about unmatched rcu_irq_{enter,exit}().

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:35:24 -08:00
Paul E. McKenney 39abefe743 rcu: Repair rcu_nmi_exit() docbook header
This commit removes the "@irq" argument from the rcu_nmi_exit() docbook
header, given that this function now has no arguments.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:35:23 -08:00
Paul E. McKenney 5a0874c1d1 rcu: Remove preemption disabling from expedited CPU selection
It turns out that it is queue_delayed_work_on() rather than
queue_work_on() that has difficulties when used concurrently with
CPU-hotplug removal operations.  It is therefore unnecessary to protect
CPU identification and queue_work_on() with preempt_disable().

This commit therefore removes the preempt_disable() and preempt_enable()
from sync_rcu_exp_select_cpus(), which has the further benefit of reducing
the number of changes that must be maintained in the -rt patchset.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Sebastian Siewior <bigeasy@linutronix.de>
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:35:23 -08:00
Paul E. McKenney fb60e533be rcu: Rename rcu_process_callbacks() to rcu_core() for Tree RCU
Although the name rcu_process_callbacks() still makes sense for Tiny
RCU, where most of what it does is invoke callbacks, it no longer makes
much sense for Tree RCU, especially given that the actually callback
invocation is relegated to rcu_do_batch(), or, for no-CBs CPUs, to the
rcuo kthreads.  Especially in the latter case, rcu_process_callbacks()
has very little to do with actual callbacks.  A better description of
this function is that it performs RCU's core processing.

This commit therefore changes the name of Tree RCU's rcu_process_callbacks()
function to rcu_core(), which also has the virtue of being consistent with
the existing invoke_rcu_core() function.

While in the area, the header comment is reworked.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:35:22 -08:00
Paul E. McKenney c98cac603f rcu: Rename rcu_check_callbacks() to rcu_sched_clock_irq()
The name rcu_check_callbacks() arguably made sense back in the early
2000s when RCU was quite a bit simpler than it is today, but it has
become quite misleading, especially with the advent of dyntick-idle
and NO_HZ_FULL.  The rcu_check_callbacks() function is RCU's hook into
the scheduling-clock interrupt, and is now but one of many ways that
callbacks get promoted to invocable state.

This commit therefore changes the name to rcu_sched_clock_irq(),
which is the same number of characters and clearly indicates this
function's relation to the rest of the Linux kernel.  In addition, for
the sake of consistency, rcu_flavor_check_callbacks() is also renamed
to rcu_flavor_sched_clock_irq().

While in the area, the header comments for both functions are reworked.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:35:21 -08:00
Paul E. McKenney 7a968bb26a Merge branches 'consolidate.2019.01.26a' and 'fwd.2019.01.26a' into HEAD
consolidate.2019.01.26a: RCU flavor consolidation cleanups.
fwd.2019.01.26a: RCU grace-period forward-progress fixes.
2019-01-25 15:32:01 -08:00
Zhang, Jun 13dc7d0c7a rcu: Prevent needless ->gp_seq_needed update in __note_gp_changes()
Currently, __note_gp_changes() checks to see if the rcu_node structure's
->gp_seq_needed is greater than or equal to that of the rcu_data
structure, and if so, updates the rcu_data structure's ->gp_seq_needed
field.  This results in a useless store in the case where the two fields
are equal.

This commit therefore carries out this store only in the case where the
rcu_node structure's ->gp_seq_needed is strictly greater than that of
the rcu_data structure.

Signed-off-by: "Zhang, Jun" <jun.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Link: https://lkml.kernel.org/r/88DC34334CA3444C85D647DBFA962C2735AD5F77@SHSMSX104.ccr.corp.intel.com
2019-01-25 15:30:00 -08:00
Zhang, Jun 1d1f898df6 rcu: Do RCU GP kthread self-wakeup from softirq and interrupt
The rcu_gp_kthread_wake() function is invoked when it might be necessary
to wake the RCU grace-period kthread.  Because self-wakeups are normally
a useless waste of CPU cycles, if rcu_gp_kthread_wake() is invoked from
this kthread, it naturally refuses to do the wakeup.

Unfortunately, natural though it might be, this heuristic fails when
rcu_gp_kthread_wake() is invoked from an interrupt or softirq handler
that interrupted the grace-period kthread just after the final check of
the wait-event condition but just before the schedule() call.  In this
case, a wakeup is required, even though the call to rcu_gp_kthread_wake()
is within the RCU grace-period kthread's context.  Failing to provide
this wakeup can result in grace periods failing to start, which in turn
results in out-of-memory conditions.

This race window is quite narrow, but it actually did happen during real
testing.  It would of course need to be fixed even if it was strictly
theoretical in nature.

This patch does not Cc stable because it does not apply cleanly to
earlier kernel versions.

Fixes: 48a7639ce8 ("rcu: Make callers awaken grace-period kthread")
Reported-by: "He, Bo" <bo.he@intel.com>
Co-developed-by: "Zhang, Jun" <jun.zhang@intel.com>
Co-developed-by: "He, Bo" <bo.he@intel.com>
Co-developed-by: "xiao, jin" <jin.xiao@intel.com>
Co-developed-by: Bai, Jie A <jie.a.bai@intel.com>
Signed-off: "Zhang, Jun" <jun.zhang@intel.com>
Signed-off: "He, Bo" <bo.he@intel.com>
Signed-off: "xiao, jin" <jin.xiao@intel.com>
Signed-off: Bai, Jie A <jie.a.bai@intel.com>
Signed-off-by: "Zhang, Jun" <jun.zhang@intel.com>
[ paulmck: Switch from !in_softirq() to "!in_interrupt() &&
  !in_serving_softirq() to avoid redundant wakeups and to also handle the
  interrupt-handler scenario as well as the softirq-handler scenario that
  actually occurred in testing. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Link: https://lkml.kernel.org/r/CD6925E8781EFD4D8E11882D20FC406D52A11F61@SHSMSX104.ccr.corp.intel.com
2019-01-25 15:29:59 -08:00
Paul E. McKenney 2ccaff10f7 rcu: Add sysrq rcu_node-dump capability
Life is hard if RCU manages to get stuck without triggering RCU CPU
stall warnings or triggering the rcu_check_gp_start_stall() checks
for failing to start a grace period.  This commit therefore adds a
boot-time-selectable sysrq key (commandeering "y") that allows manually
dumping Tree RCU state.  The new rcutree.sysrq_rcu kernel boot parameter
must be set for this sysrq to be available.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:29:59 -08:00
Paul E. McKenney 3b6505fd8e rcu: Protect rcu_check_gp_kthread_starvation() access to ->gp_flags
The rcu_check_gp_kthread_starvation() function can be invoked without
holding locks, so the access to the rcu_state structure's ->gp_flags
field must be protected with READ_ONCE().  This commit therefore adds
this protection.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:29:58 -08:00
Paul E. McKenney fd897573fa rcu: Improve diagnostics for failed RCU grace-period start
If a grace period fails to start (for example, because you commented
out the last two lines of rcu_accelerate_cbs_unlocked()), rcu_core()
will invoke rcu_check_gp_start_stall(), which will notice and complain.
However, this complaint is lacking crucial debugging information such
as when the last wakeup executed and what the value of ->gp_seq was at
that time.  This commit therefore removes the current pr_alert() from
rcu_check_gp_start_stall(), instead invoking show_rcu_gp_kthreads(),
which has been updated to print the needed information, which is collected
by rcu_gp_kthread_wake().

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:29:57 -08:00
Paul E. McKenney a9fefdb257 rcu: Update NOCB comments
This commit updates a few obsolete comments in the RCU callback-offload
code.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:29:57 -08:00
Paul E. McKenney b2c1955b88 rcu: Remove unused rcu_cpu_kthread_cpu per-CPU variable
The rcu_cpu_kthread_cpu used to provide debugfs information, but is no
longer used.  This commit therefore removes it.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:29:56 -08:00
Paul E. McKenney f7e972ee12 rcu: Move rcu_cpu_has_work to rcu_data structure
Given that RCU has a perfectly good per-CPU rcu_data structure, most
per-CPU quantities should be stored there.

This commit therefore moves the rcu_cpu_has_work per-CPU variable to
the rcu_data structure.  This also makes this variable unconditionally
present, which should be acceptable given the memory reduction due to the
RCU flavor consolidation and also due to simplifications this will enable.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:29:56 -08:00
Paul E. McKenney 8b4d0f4858 rcu: Remove unused rcu_cpu_kthread_loops per-CPU variable
The rcu_cpu_kthread_loops variable used to provide debugfs information,
but is no longer used.  This commit therefore removes it.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:29:55 -08:00
Paul E. McKenney 6ffdde28b7 rcu: Move rcu_cpu_kthread_status to rcu_data structure
Given that RCU has a perfectly good per-CPU rcu_data structure, most
per-CPU quantities should be stored there.

This commit therefore moves the rcu_cpu_kthread_status per-CPU variable
to the rcu_data structure.  This also makes this variable unconditionally
present, which should be acceptable given the memory reduction due to the
RCU flavor consolidation and also due to simplifications this will enable.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:29:54 -08:00
Paul E. McKenney 37f62d7cf0 rcu: Move rcu_cpu_kthread_task to rcu_data structure
Given that RCU has a perfectly good per-CPU rcu_data structure, most
per-CPU quantities should be stored there.

This commit therefore moves the rcu_cpu_kthread_task per-CPU variable to
the rcu_data structure.  This also makes this variable unconditionally
present, which should be acceptable given the memory reduction due to the
RCU flavor consolidation and also due to simplifications this will enable.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:29:53 -08:00
Paul E. McKenney 9cf422a8e7 rcu: Accommodate zero jiffies_till_first_fqs and kthread kicking
It is perfectly fine to set the rcutree.jiffies_till_first_fqs boot
parameter to zero, in fact, this can be useful on specialty systems that
usually have at least one idle CPU and that need fast grace periods.
This is because this setting causes the RCU grace-period kthread to
scan for idle threads immediately after grace-period initialization,
as opposed to waiting several jiffies to do so.

It is also perfectly fine to set the rcutree.rcu_kick_kthreads kernel
parameter, which gives the RCU grace-period kthread an extra wakeup
if it doesn't make progress for a period of three times the setting of
the rcutree.jiffies_till_first_fqs boot parameter.  This is of course
problematic when the value of this parameter is zero, as it can result
in unnecessary wakeup IPIs along with unnecessary WARN_ONCE() invocations.

This commit therefore defers kthread kicking for at least two jiffies,
regardless of the setting of rcutree.jiffies_till_first_fqs.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:29:53 -08:00
Paul E. McKenney 260e1e4fd8 rcu: Discard separate per-CPU callback counts
Back when there were multiple flavors of RCU, it was necessary to
separately count lazy and non-lazy callbacks for each CPU.  These counts
were used in CONFIG_RCU_FAST_NO_HZ kernels to determine how long a newly
idle CPU should be allowed to sleep before handling its RCU callbacks.
But now that there is only one flavor, the callback counts for a given
CPU's sole rcu_data structure are the counts for that CPU.

This commit therefore removes the rcu_data structure's ->nonlazy_posted
and ->nonlazy_posted_snap fields, the rcu_idle_count_callbacks_posted()
and rcu_cpu_has_callbacks() functions, repurposes the rcu_data structure's
->all_lazy field to record the laziness state at the beginning of the
latest idle sojourn, and modifies CONFIG_RCU_FAST_NO_HZ RCU CPU stall
warnings accordingly.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:28:30 -08:00
Paul E. McKenney 8923072664 rcu: Inline _synchronize_rcu_expedited() into synchronize_rcu_expedited()
Now that _synchronize_rcu_expedited() has only one caller, and given that
this is a tail call, this commit inlines _synchronize_rcu_expedited()
into synchronize_rcu_expedited().

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:28:29 -08:00
Paul E. McKenney e5bc3af773 rcu: Consolidate PREEMPT and !PREEMPT synchronize_rcu()
Now that rcu_blocking_is_gp() makes the correct immediate-return
decision for both PREEMPT and !PREEMPT, a single implementation of
synchronize_rcu() will work correctly under both configurations.
This commit therefore eliminates a few lines of code by consolidating
the two implementations of synchronize_rcu().

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:28:28 -08:00
Paul E. McKenney 3cd4ca47aa rcu: Consolidate PREEMPT and !PREEMPT synchronize_rcu_expedited()
The CONFIG_PREEMPT=n and CONFIG_PREEMPT=y implementations of
synchronize_rcu_expedited() are quite similar, and with small
modifications to rcu_blocking_is_gp() can be made identical.  This commit
therefore makes this change in order to save a few lines of code and to
reduce the amount of duplicate code.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:28:27 -08:00
Paul E. McKenney 142d106d5e rcu: Determine expedited-GP IPI handler at build time
Back when there could be multiple RCU flavors running in the same kernel
at the same time, it was necessary to specify the expedited grace-period
IPI handler at runtime.  Now that there is only one RCU flavor, the
IPI handler can be determined at build time.  There is therefore no
longer any reason for the RCU-preempt and RCU-sched IPI handlers to
have different names, nor is there any reason to pass these handlers in
function arguments and in the data structures enclosing workqueues.

This commit therefore makes all these changes, pushing the specification
of the expedited grace-period IPI handler down to the point of use.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:28:27 -08:00
Paul E. McKenney c46f497a61 rcu: Inline rcu_kthread_do_work() into its sole remaining caller
The rcu_kthread_do_work() function has a single-line body and only one
remaining caller.  This commit therefore saves a few lines of code by
inlining rcu_kthread_do_work() into its sole remaining caller.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:28:25 -08:00
Paul E. McKenney c97058d033 rcu: Eliminate RCU_BH_FLAVOR and RCU_SCHED_FLAVOR
Now that the RCU flavors have been consolidated, RCU_BH_FLAVOR and
RCU_SCHED_FLAVOR are no longer used.  This commit therefore saves a
few lines by removing them.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:28:25 -08:00
Paul E. McKenney cd920e5a34 rcu: Inline force_quiescent_state() into rcu_force_quiescent_state()
Given that rcu_force_quiescent_state() is a simple wrapper around
force_quiescent_state(), this commit saves a few lines of code by
inlining force_quiescent_state() into rcu_force_quiescent_state(),
and changing all references to force_quiescent_state() to instead
invoke rcu_force_quiescent_state().

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:28:24 -08:00
Paul E. McKenney 1de462ed85 rcu: Make expedited IPI handler return after handling critical section
During expedited RCU grace-period initialization, IPIs are sent to
all non-idle online CPUs.  The IPI handler checks to see if the CPU is
in quiescent state, reporting one if so.  This handler looks at three
different cases: (1) The CPU is not in an rcu_read_lock()-based critical
section, (2) The CPU is in the process of exiting an rcu_read_lock()-based
critical section, and (3) The CPU is in an rcu_read_lock()-based critical
section.  In case (2), execution falls through into case (3).

This is harmless from a functionality viewpoint, but can result in
needless overhead during an improbable corner case.  This commit therefore
adds the "return" statement needed to prevent fall-through.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:28:24 -08:00
Paul E. McKenney ad368d15b0 rcu: Rename and comment changes due to only one rcuo kthread per CPU
Given RCU flavor consolidation, the name rcu_spawn_all_nocb_kthreads()
is quite misleading.  It no longer ever creates more than one kthread,
and it does so only for the specified CPU.  This commit therefore changes
this name to the more descriptive rcu_spawn_cpu_nocb_kthread(), and also
fixes up a similar issue in its header comment while in the area.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25 15:28:23 -08:00
Paul E. McKenney a4cffdad73 time: Move CONTEXT_TRACKING to kernel/time/Kconfig
Both CONTEXT_TRACKING and CONTEXT_TRACKING_FORCE are currently defined
in kernel/rcu/kconfig, which might have made sense at some point, but
no longer does given that RCU refers to neither of these Kconfig options.

Therefore move them to kernel/time/Kconfig, where the rest of the
NO_HZ_FULL Kconfig options live.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: https://lkml.kernel.org/r/20181220170525.GA12579@linux.ibm.com
2019-01-15 11:16:41 +01:00
Paul E. McKenney 5ac7cdc298 rcutorture: Don't do busted forward-progress testing
The "busted" rcutorture type is an intentionally broken implementation
of RCU.  Doing forward-progress testing on this implementation is not
particularly meaningful on the one hand and can result in fatal abuse
of the memory allocator on the other.  This commit therefore disables
forward-progress testing of the "busted" rcutorture type.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-12-01 12:45:42 -08:00
Paul E. McKenney 2e57bf97a6 rcutorture: Use 100ms buckets for forward-progress callback histograms
This commit narrows the scope of each bucket of the forward-progress
callback-invocation histograms from one second to 100 milliseconds, which
aids debugging of forward-progress problems by making shorter-duration
callback-invocation stalls visible.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-12-01 12:45:41 -08:00
Paul E. McKenney 2667ccce93 rcutorture: Recover from OOM during forward-progress tests
This commit causes the OOM handler to do rcu_barrier() calls and to
free up forward-progress callbacks in order to recover from OOM events.
The current test is terminated, but subsequent forward-progress tests can
proceed.  This allows a long test to result in multiple forward-progress
failures, greatly reducing the required testing time.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-12-01 12:45:41 -08:00