Commit Graph

206 Commits

Author SHA1 Message Date
Paul E. McKenney
0032f4e889 rcutorture: Dump writer stack if stalled
Right now, rcutorture warns if an rcu_torture_writer() kthread stalls,
but this warning is not always all that helpful.  This commit therefore
makes the first such warning include a stack dump.

This in turn requires that sched_show_task() be exported to GPL modules,
so this commit makes that change as well.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-10-09 14:26:09 -07:00
Paul E. McKenney
2b1516e55f rcutorture: Add interrupt-disable capability to stall-warning tests
When rcutorture sees the rcutorture.stall_cpu kernel boot parameter,
it loops with preemption disabled, which does in fact normally
generate an RCU CPU stall warning message.  However, there are test
scenarios that need the stalling CPU to have interrupts disabled.
This commit therefore adds an rcutorture.stall_cpu_irqsoff kernel
boot parameter that causes the stalling CPU to disable interrupts.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-10-09 14:26:08 -07:00
Paul E. McKenney
656e7c0c0a 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
doc.2017.08.17a: Documentation updates.
fixes.2017.08.17a: RCU fixes.
hotplug.2017.07.25b: CPU-hotplug updates.
misc.2017.08.17a: Miscellaneous fixes outside of RCU (give or take conflicts).
spin_unlock_wait_no.2017.08.17a: Remove spin_unlock_wait().
srcu.2017.07.27c: SRCU updates.
torture.2017.07.24c: Torture-test updates.
2017-08-17 08:10:04 -07:00
Paul E. McKenney
7e42776d5e rcu: Drive TASKS_RCU directly off of PREEMPT
The actual use of TASKS_RCU is only when PREEMPT, otherwise RCU-sched
is used instead.  This commit therefore makes synchronize_rcu_tasks()
and call_rcu_tasks() available always, but mapped to synchronize_sched()
and call_rcu_sched(), respectively, when !PREEMPT.  This approach also
allows some #ifdefs to be removed from rcutorture.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
2017-08-17 07:26:04 -07:00
Paul E. McKenney
f34c8585ed rcutorture: Invoke call_rcu() from timer handler
The Linux kernel invokes call_rcu() from various interrupt/softirq
handlers, but rcutorture does not.  This commit therefore adds this
behavior to rcutorture's repertoire.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-07-24 16:04:19 -07:00
Paul E. McKenney
a3b7b6c273 rcutorture: Eliminate unused ts_rem local from rcu_trace_clock_local()
This commit removes an unused local variable named ts_rem that is
marked __maybe_unused.  Yes, the variable was assigned to, but it
was never used beyond that point, hence not needed.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-07-24 16:04:17 -07:00
Paul E. McKenney
808de39cf4 rcutorture: Add task's CPU for rcutorture writer stalls
It appears that at least some of the rcutorture writer stall messages
coincide with unusually long CPU-online operations, for example, no
fewer than 205 seconds in a recent test.  It is of course possible that
the writer stall is not unrelated to this unusually long CPU-hotplug
operation, and so this commit adds the rcutorture writer task's CPU to
the stall message to gain more information about this possible connection.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-07-24 16:04:17 -07:00
Paul E. McKenney
b3c983142d rcutorture: Place event-traced strings into trace buffer
Strings used in event tracing need to be specially handled, for example,
being copied to the trace buffer instead of being pointed to by the trace
buffer.  Although the TPS() macro can be used to "launder" pointed-to
strings, this might not be all that effective within a loadable module.
This commit therefore copies rcutorture's strings to the trace buffer.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
2017-07-24 16:04:12 -07:00
Paul E. McKenney
5e741fa9e9 rcutorture: Enable SRCU readers from timer handler
Now that it is legal to invoke srcu_read_lock() and srcu_read_unlock()
for a given srcu_struct from both process context and {soft,}irq
handlers, it is time to test it.  This commit therefore enables
testing of SRCU readers from rcutorture's timer handler, using in_task()
to determine whether or not it is safe to sleep in the SRCU read-side
critical sections.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-07-24 16:04:11 -07:00
Paul E. McKenney
115a1a5285 rcutorture: Move SRCU status printing to SRCU implementations
This commit gets rid of some ugly #ifdefs in rcutorture.c by moving
the SRCU status printing to the SRCU implementations.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-07-24 16:04:08 -07:00
Paul E. McKenney
bd8cc5a062 srcu: Remove Classic SRCU
Classic SRCU was only ever intended to be a fallback in case of issues
with Tree/Tiny SRCU, and the latter two are doing quite well in testing.
This commit therefore removes Classic SRCU.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-06-08 18:52:42 -07:00
Paul E. McKenney
25c36329a3 rcu: Move expediting-related access/control out of rcupdate.h
The rcu_gp_is_normal(), rcu_gp_is_expedited(), rcu_expedite_gp(), and
rcu_unexpedite_gp() functions are intended only for use within the
RCU implementation itself -- the sysfs access is what should be used
outside of RCU.  This commit therefore moves the declarations for
these functions to kernel/rcu/rcu.h, and also includes this file into
kernel/rcu/rcutorture.c and kernel/rcu/rcuperf.c.  This also has the
beneficial effect of shrinking rcupdate.c a bit.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-06-08 18:52:28 -07:00
Paul E. McKenney
3ddf20c953 srcu: Shrink Tiny SRCU a bit more
This commit rearranges Tiny SRCU's srcu_struct structure, substitutes
u8 for bool, and shrinks counters down to short.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-06-08 08:25:31 -07:00
Paul E. McKenney
7f6733c3c6 srcu: Make rcutorture writer stalls print SRCU GP state
In the past, SRCU was simple enough that there was little point in
making the rcutorture writer stall messages print the SRCU grace-period
number state.  With the advent of Tree SRCU, this has changed.  This
commit therefore makes Classic, Tiny, and Tree SRCU report this state
to rcutorture as needed.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Mike Galbraith <efault@gmx.de>
2017-04-26 11:23:28 -07:00
Paul E. McKenney
da915ad5cf srcu: Parallelize callback handling
Peter Zijlstra proposed using SRCU to reduce mmap_sem contention [1,2],
however, there are workloads that could result in a high volume of
concurrent invocations of call_srcu(), which with current SRCU would
result in excessive lock contention on the srcu_struct structure's
->queue_lock, which protects SRCU's callback lists.  This commit therefore
moves SRCU to per-CPU callback lists, thus greatly reducing contention.

Because a given SRCU instance no longer has a single centralized callback
list, starting grace periods and invoking callbacks are both more complex
than in the single-list Classic SRCU implementation.  Starting grace
periods and handling callbacks are now handled using an srcu_node tree
that is in some ways similar to the rcu_node trees used by RCU-bh,
RCU-preempt, and RCU-sched (for example, the srcu_node tree shape is
controlled by exactly the same Kconfig options and boot parameters that
control the shape of the rcu_node tree).

In addition, the old per-CPU srcu_array structure is now named srcu_data
and contains an rcu_segcblist structure named ->srcu_cblist for its
callbacks (and a spinlock to protect this).  The srcu_struct gets
an srcu_gp_seq that is used to associate callback segments with the
corresponding completion-time grace-period number.  These completion-time
grace-period numbers are propagated up the srcu_node tree so that the
grace-period workqueue handler can determine whether additional grace
periods are needed on the one hand and where to look for callbacks that
are ready to be invoked.

The srcu_barrier() function must now wait on all instances of the per-CPU
->srcu_cblist.  Because each ->srcu_cblist is protected by ->lock,
srcu_barrier() can remotely add the needed callbacks.  In theory,
it could also remotely start grace periods, but in practice doing so
is complex and racy.  And interestingly enough, it is never necessary
for srcu_barrier() to start a grace period because srcu_barrier() only
enqueues a callback when a callback is already present--and it turns out
that a grace period has to have already been started for this pre-existing
callback.  Furthermore, it is only the callback that srcu_barrier()
needs to wait on, not any particular grace period.  Therefore, a new
rcu_segcblist_entrain() function enqueues the srcu_barrier() function's
callback into the same segment occupied by the last pre-existing callback
in the list.  The special case where all the pre-existing callbacks are
on a different list (because they are in the process of being invoked)
is handled by enqueuing srcu_barrier()'s callback into the RCU_DONE_TAIL
segment, relying on the done-callbacks check that takes place after all
callbacks are inovked.

Note that the readers use the same algorithm as before.  Note that there
is a separate srcu_idx that tells the readers what counter to increment.
This unfortunately cannot be combined with srcu_gp_seq because they
need to be incremented at different times.

This commit introduces some ugly #ifdefs in rcutorture.  These will go
away when I feel good enough about Tree SRCU to ditch Classic SRCU.

Some crude performance comparisons, courtesy of a quickly hacked rcuperf
asynchronous-grace-period capability:

			Callback Queuing Overhead
			-------------------------
	# CPUS		Classic SRCU	Tree SRCU
	------          ------------    ---------
	     2              0.349 us     0.342 us
	    16             31.66  us     0.4   us
	    41             ---------     0.417 us

The times are the 90th percentiles, a statistic that was chosen to reject
the overheads of the occasional srcu_barrier() call needed to avoid OOMing
the test machine.  The rcuperf test hangs when running Classic SRCU at 41
CPUs, hence the line of dashes.  Despite the hacks to both the rcuperf code
and that statistics, this is a convincing demonstration of Tree SRCU's
performance and scalability advantages.

[1] https://lwn.net/Articles/309030/
[2] https://patchwork.kernel.org/patch/5108281/

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Fix initialization if synchronize_srcu_expedited() called first. ]
2017-04-21 05:59:26 -07:00
Paul E. McKenney
dad81a2026 srcu: Introduce CLASSIC_SRCU Kconfig option
The TREE_SRCU rewrite is large and a bit on the non-simple side, so
this commit helps reduce risk by allowing the old v4.11 SRCU algorithm
to be selected using a new CLASSIC_SRCU Kconfig option that depends
on RCU_EXPERT.  The default is to use the new TREE_SRCU and TINY_SRCU
algorithms, in order to help get these the testing that they need.
However, if your users do not require the update-side scalability that
is to be provided by TREE_SRCU, select RCU_EXPERT and then CLASSIC_SRCU
to revert back to the old classic SRCU algorithm.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18 11:38:23 -07:00
Paul E. McKenney
32071141b2 srcutorture: Print Tiny SRCU reader statistics
The srcu_torture_stats() function is adapted to the specific srcu_struct
layout traditionally used by SRCU.  This commit therefore adds support
for Tiny SRCU.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18 11:38:22 -07:00
Paul E. McKenney
d8be81735a srcu: Create a tiny SRCU
In response to automated complaints about modifications to SRCU
increasing its size, this commit creates a tiny SRCU that is
used in SMP=n && PREEMPT=n builds.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18 11:38:22 -07:00
Ingo Molnar
174cd4b1e5 sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>
Fix up affected files that include this signal functionality via sched.h.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:32 +01:00
Ingo Molnar
ae7e81c077 sched/headers: Prepare for new header dependencies before moving code to <uapi/linux/sched/types.h>
We are going to move scheduler ABI details to <uapi/linux/sched/types.h>,
which will be used from a number of .c files.

Create empty placeholder header that maps to <linux/types.h>.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:27 +01:00
Lance Roy
f2c4689640 srcu: Implement more-efficient reader counts
SRCU uses two per-cpu counters: a nesting counter to count the number of
active critical sections, and a sequence counter to ensure that the nesting
counters don't change while they are being added together in
srcu_readers_active_idx_check().

This patch instead uses per-cpu lock and unlock counters. Because both
counters only increase and srcu_readers_active_idx_check() reads the unlock
counter before the lock counter, this achieves the same end without having
to increment two different counters in srcu_read_lock(). This also saves a
smp_mb() in srcu_readers_active_idx_check().

Possible bug: There is no guarantee that the lock counter won't overflow
during srcu_readers_active_idx_check(), as there are no memory barriers
around srcu_flip() (see comment in srcu_readers_active_idx_check() for
details). However, this problem was already present before this patch.

Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Lance Roy <ldr709@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-01-25 12:53:20 -08:00
Paul E. McKenney
d0af39e89e torture: Trace long read-side delays
Although rcutorture will occasionally do a 50-millisecond grace-period
delay, these delays are quite rare.  And rightly so, because otherwise
the read rate would be quite low.  Thie means that it can be important
to identify whether or not a given run contained a long-delay read.
This commit therefore inserts a trace_rcu_torture_read() event to flag
runs containing long delays.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-11-14 10:46:30 -08:00
Paul E. McKenney
d74b62bc32 Merge branches 'doc.2016.08.22c', 'exp.2016.08.22c', 'fixes.2016.09.14a', 'hotplug.2016.08.22c' and 'torture.2016.08.22c' into HEAD
doc.2016.08.22c: Documentation updates
exp.2016.08.22c: Expedited grace-period updates
fixes.2016.09.14a: Miscellaneous fixes
hotplug.2016.08.22c: CPU-hotplug changes
torture.2016.08.22c: Torture-test changes
2016-09-14 12:58:49 -07:00
SeongJae Park
472213a675 rcutorture: Print out barrier error as document says
Tests for rcu_barrier() were introduced by commit fae4b54f28 ("rcu:
Introduce rcutorture testing for rcu_barrier()").  This commit updated
the documentation to say that the "rtbe" field in rcutorture's dmesg
output indicates test failure.  However, the code was not updated, only
the documentation.  This commit therefore updates the code to match the
updated documentation.

Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-08-22 10:03:37 -07:00
Paul E. McKenney
4ffa669924 torture: Add task state to writer-task stall printk()s
This commit adds a dump of the scheduler state for stalled rcutorture
writer tasks.  This addition provides yet more debug for the intermittent
"failures to proceed", where grace periods move ahead but the rcutorture
writer tasks fail to do so.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-08-22 10:02:59 -07:00
Sebastian Andrzej Siewior
0ffd374b22 rcutorture: Convert to hotplug state machine
Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Cc: Josh Triplett <josh@joshtriplett.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-08-22 09:52:12 -07:00
Paul E. McKenney
4d03754f04 Merge branches 'doc.2016.06.15a', 'fixes.2016.06.15b' and 'torture.2016.06.14a' into HEAD
doc.2016.06.15a: Documentation updates
fixes.2016.06.15b: Documentation updates
torture.2016.06.14a: Documentation updates
2016-06-15 16:58:03 -07:00
Paul E. McKenney
aab057382c rcu: Fix a typo in a comment
In the area in hot pursuit of a bug, so might as well clean it up.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-06-15 15:59:10 -07:00
Paul E. McKenney
4e9a073f60 torture: Remove CONFIG_RCU_TORTURE_TEST_RUNNABLE, simplify code
This commit removes CONFIG_RCU_TORTURE_TEST_RUNNABLE in favor of the
already-existing rcutorture.torture_runnable kernel boot parameter.
It also converts an #ifdef into IS_ENABLED(), saving a few lines of code.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-06-14 16:02:15 -07:00
Paul E. McKenney
0aa67e75b3 rcutorture: Add irqs-disabled test for call_rcu()
Mutation testing carried out by Iftekhar Ahmed of Oregon State
University showed that rcutorture is failing to test invocations
of call_rcu() having interrupts disabled.  This commit therefore
adds interrupt disabling around one of the existing invocations
of call_rcu() (and friends).

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-04-21 13:47:04 -07:00
Anna-Maria Gleixner
de26ca19a5 rcutorture: Consider FROZEN hotplug notifier transitions
The hotplug notifier rcutorture_cpu_notify() doesn't consider the
corresponding CPU_XXX_FROZEN transitions. They occur on
suspend/resume and are usually handled the same way as the
corresponding non frozen transitions.

Mask the switch case action argument with '~CPU_TASKS_FROZEN' to map
CPU_XXX_FROZEN hotplug transitions on corresponding non-frozen
transitions.

Cc: Josh Triplett <josh@joshtriplett.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:39:52 -07:00
Paul E. McKenney
67522beecf rcutorture: Remove redundant initialization to zero
The current code initializes the global per-CPU variables
rcu_torture_count and rcu_torture_batch to zero.  However, C does this
initialization by default, and explicit initialization of per-CPU
variables now needs a different syntax if "make tags" is to work.
This commit therefore removes the initialization.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:39:51 -07:00
Paul E. McKenney
9efafb8849 rcutorture: Allow for rcupdate.rcu_normal
Currently, rcu_torture_writer() checks only for rcu_gp_is_expedited()
when deciding whether or not to do dynamic control of RCU expediting.
This means that if rcupdate.rcu_normal is specified, rcu_torture_writer()
will attempt to dynamically control RCU expediting, but will nonetheless
only test normal RCU grace periods.  This commit therefore adds a check
for !rcu_gp_is_normal(), and prints a message and desists from testing
dynamic control of RCU expediting when doing so is futile.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:37:37 -07:00
Paul E. McKenney
274529ba9b rcu: Consolidate dumping of ftrace buffer
This commit consolidates a couple definitions and several calls for
single-shot ftrace-buffer dumping.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:29:08 -07:00
Linus Torvalds
271ecc5253 Merge branch 'akpm' (patches from Andrew)
Merge first patch-bomb from Andrew Morton:

 - some misc things

 - ofs2 updates

 - about half of MM

 - checkpatch updates

 - autofs4 update

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (120 commits)
  autofs4: fix string.h include in auto_dev-ioctl.h
  autofs4: use pr_xxx() macros directly for logging
  autofs4: change log print macros to not insert newline
  autofs4: make autofs log prints consistent
  autofs4: fix some white space errors
  autofs4: fix invalid ioctl return in autofs4_root_ioctl_unlocked()
  autofs4: fix coding style line length in autofs4_wait()
  autofs4: fix coding style problem in autofs4_get_set_timeout()
  autofs4: coding style fixes
  autofs: show pipe inode in mount options
  kallsyms: add support for relative offsets in kallsyms address table
  kallsyms: don't overload absolute symbol type for percpu symbols
  x86: kallsyms: disable absolute percpu symbols on !SMP
  checkpatch: fix another left brace warning
  checkpatch: improve UNSPECIFIED_INT test for bare signed/unsigned uses
  checkpatch: warn on bare unsigned or signed declarations without int
  checkpatch: exclude asm volatile from complex macro check
  mm: memcontrol: drop unnecessary lru locking from mem_cgroup_migrate()
  mm: migrate: consolidate mem_cgroup_migrate() calls
  mm/compaction: speed up pageblock_pfn_to_page() when zone is contiguous
  ...
2016-03-16 11:51:08 -07:00
Peter Zijlstra
25528213fe tags: Fix DEFINE_PER_CPU expansions
$ make tags
  GEN     tags
ctags: Warning: drivers/acpi/processor_idle.c:64: null expansion of name pattern "\1"
ctags: Warning: drivers/xen/events/events_2l.c:41: null expansion of name pattern "\1"
ctags: Warning: kernel/locking/lockdep.c:151: null expansion of name pattern "\1"
ctags: Warning: kernel/rcu/rcutorture.c:133: null expansion of name pattern "\1"
ctags: Warning: kernel/rcu/rcutorture.c:135: null expansion of name pattern "\1"
ctags: Warning: kernel/workqueue.c:323: null expansion of name pattern "\1"
ctags: Warning: net/ipv4/syncookies.c:53: null expansion of name pattern "\1"
ctags: Warning: net/ipv6/syncookies.c:44: null expansion of name pattern "\1"
ctags: Warning: net/rds/page.c:45: null expansion of name pattern "\1"

Which are all the result of the DEFINE_PER_CPU pattern:

  scripts/tags.sh:200:	'/\<DEFINE_PER_CPU([^,]*, *\([[:alnum:]_]*\)/\1/v/'
  scripts/tags.sh:201:	'/\<DEFINE_PER_CPU_SHARED_ALIGNED([^,]*, *\([[:alnum:]_]*\)/\1/v/'

The below cures them. All except the workqueue one are within reasonable
distance of the 80 char limit. TJ do you have any preference on how to
fix the wq one, or shall we just not care its too long?

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-15 16:55:16 -07:00
Paul E. McKenney
aa5a898876 rcutorture: Correct no-expedite console messages
The "Disabled dynamic grace-period expediting" console message is
currently printed unconditionally.  This commit causes it to be
output only when it is impossible to switch between normal and
expedited grace periods, which was the original intent.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-02-23 19:59:52 -08:00
Paul E. McKenney
18aff33e73 rcutorture: Print symbolic name for rcu_torture_writer_state
Currently, rcu_torture_writer_state is printed as an integer, which slows
debugging.  This commit therefore prints a symbolic name in addition to
the integer.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: More "const", as suggested by Josh Triplett. ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-12-05 17:58:22 -08:00
Paul E. McKenney
39cd2dd39a Merge branches 'doc.2015.10.06a', 'percpu-rwsem.2015.10.06a' and 'torture.2015.10.06a' into HEAD
doc.2015.10.06a:  Documentation updates.
percpu-rwsem.2015.10.06a:  Optimization of per-CPU reader-writer semaphores.
torture.2015.10.06a:  Torture-test updates.
2015-10-07 16:06:25 -07:00
Paul E. McKenney
4f441a258f rcutorture: Fix unused-function warning for torturing_tasks()
The torturing_tasks() function is used only in kernels built with
CONFIG_PROVE_RCU=y, so the second definition can result in unused-function
compiler warnings.  This commit adds __maybe_unused to suppress these
warnings.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-10-06 11:28:09 -07:00
Paul E. McKenney
889d487a26 rcutorture: Fix module unwind when bad torture_type specified
The rcutorture module has a list of torture types, and specifying a
type not on this list is supposed to cleanly fail the module load.
Unfortunately, the "fail" happens without the "cleanly".  This commit
therefore adds the needed clean-up after an incorrect torture_type.

Reported-by: David Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: David Miller <davem@davemloft.net>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-10-06 11:28:01 -07:00
Paul E. McKenney
3836f5337f torture: Consolidate cond_resched_rcu_qs() into stutter_wait()
This commit moves cond_resched_rcu_qs() into stutter_wait(), saving
a line and also avoiding RCU CPU stall warnings from all torture
loops containing a stutter_wait().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-10-06 11:25:01 -07:00
Boqun Feng
db3e8db45e rcu: Use call_rcu_func_t to replace explicit type equivalents
We have had the call_rcu_func_t typedef for a quite awhile, but we still
use explicit function pointer types in some places.  These types can
confuse cscope and can be hard to read.  This patch therefore replaces
these types with the call_rcu_func_t typedef.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-10-06 11:08:19 -07:00
Boqun Feng
b6a4ae766e rcu: Use rcu_callback_t in call_rcu*() and friends
As we now have rcu_callback_t typedefs as the type of rcu callbacks, we
should use it in call_rcu*() and friends as the type of parameters. This
could save us a few lines of code and make it clear which function
requires an rcu callbacks rather than other callbacks as its argument.

Besides, this can also help cscope to generate a better database for
code reading.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-10-06 11:08:05 -07:00
Paul E. McKenney
3dbe43f6fb Merge branches 'doc.2015.07.15a' and 'torture.2015.07.15a' into HEAD
doc.2015.07.15a: Documentation updates.
torture.2015.07.15a: Torture-test updates.
2015-08-04 08:42:02 -07:00
Paul E. McKenney
24560056de rcu: Add RCU-sched flavors of get-state and cond-sync
The get_state_synchronize_rcu() and cond_synchronize_rcu() functions
allow polling for grace-period completion, with an actual wait for a
grace period occurring only when cond_synchronize_rcu() is called too
soon after the corresponding get_state_synchronize_rcu().  However,
these functions work only for vanilla RCU.  This commit adds the
get_state_synchronize_sched() and cond_synchronize_sched(), which provide
the same capability for RCU-sched.

Reported-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-22 15:26:58 -07:00
Paul E. McKenney
5be5d1a117 rcutorture: Add RCU-tasks qualifier to dereference
Although RCU-tasks isn't really designed to support rcu_dereference()
and list manipulation, that is how rcutorture tests it.  Which means
that lockdep-RCU complains about the rcu_dereference_check() invocations
because RCU-tasks doesn't have read-side markers.  This commit therefore
creates a torturing_tasks() to silence the lockdep-RCU complaints from
rcu_dereference_check() when RCU-tasks is being tortured.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-15 14:47:19 -07:00
Paul E. McKenney
3a0af33341 rcutorture: Fix rcu_torture_cbflood() for callback-free RCU
The rcu_torture_cbflood() function correctly checks for flavors of
RCU that lack analogs to call_rcu() and rcu_barrier(), but in that
case it fails to terminate correctly.  In fact, it terminates so
incorrectly that segfaults can result.  This commit therefore causes
rcu_torture_cbflood() to do the proper wait-for-stop procedure.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-15 14:47:17 -07:00
Paul E. McKenney
e8e255f719 rcutorture: Bounds-check rcutorture.shuffle_interval
Specifying a negative rcutorture.shuffle_interval value will cause a
negative value to be used as a sleep time.  This commit therefore
refuses to start shuffling unless the rcutorture.shuffle_interval
value is greater than zero.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-15 14:47:16 -07:00
Paul E. McKenney
4444d852a9 rcutorture: Check nfakewriters parameter
Currently, a negative value for rcutorture.nfakewriters= can cause
rcutorture to pass a negative size to the memory allocator, which
is not really a particularly good thing to do.  This commit therefore
adds bounds checking to this parameter, so that values that are less
than or equal to zero disable fake writing.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-15 14:47:15 -07:00
Paul E. McKenney
d9eba76883 rcutorture: Better bounds checking for n_barrier_cbs
A negative value for rcutorture.n_barrier_cbs can pass a negative value
to the memory allocator, so this commit instead causes rcu_barrier()
testing to be disabled in this case.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-15 14:47:14 -07:00
Paul E. McKenney
ca1d51ed98 rcutorture: Test SRCU cleanup code path
The current rcutorture testing does not do any cleanup operations.
This works because the srcu_struct is statically allocated, but it
does represent a memory leak of the associated dynamically allocated
->per_cpu_ref per-CPU variables.  However, rcutorture currently uses
a statically allocated srcu_struct, which cannot legally be passed to
cleanup_srcu_struct().  Therefore, this commit adds a second form
of srcu (called srcud) that dynamically allocates and frees the
associated per-CPU variables.  This commit also adds a ->cleanup()
member to rcu_torture_ops that is invoked at the end of the test,
after ->cb_barriers().  This ->cleanup() pointer is NULL for all
existing tests, and thus only used for scrud.  Finally, the SRCU-P
torture-test configuration selects scrud instead of srcu, with SRCU-N
continuing to use srcu, thereby testing both static and dynamic
srcu_struct structures.

Reported-by: "Ahmed, Iftekhar" <ahmedi@onid.oregonstate.edu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-05-27 12:59:58 -07:00
Paul E. McKenney
6c7ed42c81 rcutorture: Replace barriers with smp_store_release() and smp_load_acquire()
The rcutorture.c file uses several explicit memory barriers that can
easily be converted to smp_store_release() and smp_load_acquire(), which
improves maintainability and also improves performance a bit.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-05-27 12:59:58 -07:00
Paul E. McKenney
3838cc1850 rcutorture: Allow negative values of nreaders to oversubscribe
By default, with rcutorture.nreaders equal to -1, rcutorture provisions
N-1 reader kthreads, where N is the number of CPUs.  This avoids
rcutorture-induced stalls, but also avoids heavier levels of torture.
This commit therefore allows negative values of rcutorture.nreaders
to specify larger numbers of reader kthreads, so that for example
rcutorture.nreaders=-2 provisions N kthreads and rcutorture.nreaders=-5
provisions N+3 kthreads.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Update documentation, as suggested by Josh Triplett. ]
2015-05-27 12:59:57 -07:00
Paul E. McKenney
7d0ae8086b rcu: Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()
This commit moves from the old ACCESS_ONCE() API to the new READ_ONCE()
and WRITE_ONCE() APIs.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck:  Updated to include kernel/torture.c as suggested by Jason Low. ]
2015-05-27 12:56:15 -07:00
Paul E. McKenney
c136f99104 rcutorture: Make consistent use of variables
The "if" statement at the beginning of rcu_torture_writer() should
use the same set of variables.  In theory, this does not matter because
the corresponding variables (gp_sync and gp_sync1) have the same value
at this point in the code, but in practice such puzzles should be
removed.  This commit therefore makes the use of variables consistent.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-02-26 12:03:04 -08:00
Paul E. McKenney
4bb3c5f414 rcu: Add rcu_expedite_gp() and rcu_unexpedite_gp() to rcutorture
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-02-26 12:03:00 -08:00
Paul E. McKenney
7602de4af1 rcutorture: Add more diagnostics in rcu_barrier() test failure case
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-01-10 19:08:06 -08:00
Paul E. McKenney
917963d0b3 rcutorture: Check from beginning to end of grace period
Currently, rcutorture's Reader Batch checks measure from the end of
the previous grace period to the end of the current one.  This commit
tightens up these checks by measuring from the start and end of the same
grace period.  This involves adding rcu_batches_started() and friends
corresponding to the existing rcu_batches_completed() and friends.

We leave SRCU alone for the moment, as it does not yet have a way of
tracking both ends of its grace periods.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-01-10 19:08:02 -08:00
Paul E. McKenney
1e32eaee4c rcutorture: Drop rcu_torture_completed() and friends
Now that the return type of rcu_batches_completed() and friends matches
that of the rcu_torture_ops structure's ->completed field, the wrapper
functions can be deleted.  This commit carries out that deletion, while
also wiring "sched"'s ->completed field to rcu_batches_completed_sched().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-01-10 19:08:00 -08:00
Paul E. McKenney
6b80da42c0 rcutorture: Use unsigned for Reader Batch computations
The counter returned by the various ->completed functions is subject to
overflow, which means that subtracting two such counters might result
in overflow, which invokes undefined behavior in the C standard.  This
commit therefore changes these functions and variables to unsigned to
avoid this undefined behavior.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-01-10 19:07:58 -08:00
Paul E. McKenney
b8969d1a50 rcutorture: Fix rcu_torture_cbflood() memory leak
Commit 38706bc5a2 (rcutorture: Add callback-flood test) vmalloc()ed
a bunch of RCU callbacks, but failed to free them.  This commit fixes
that oversight.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
2014-11-03 19:26:41 -08:00
Paul E. McKenney
59da22a020 rcutorture: Rename rcutorture_runnable parameter
This commit changes rcutorture_runnable to torture_runnable, which is
consistent with the names of the other parameters and is a bit shorter
as well.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:44 -07:00
Davidlohr Bueso
d36a7a0d5e torture: Address race in module cleanup
When performing module cleanups by calling torture_cleanup() the
'torture_type' string in nullified However, callers are not necessarily
done, and might still need to reference the variable. This impacts
both rcutorture and locktorture, causing printing things like:

[   94.226618] (null)-torture: Stopping lock_torture_writer task
[   94.226624] (null)-torture: Stopping lock_torture_stats task

Thus delay this operation until the very end of the cleanup process.
The consequence (which shouldn't matter for this kid of program) is,
of course, that we delay the window between rmmod and modprobing,
for instance in module_torture_begin().

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:06 -07:00
Paul E. McKenney
96b4672703 Merge branch 'rcu-tasks.2014.09.10a' into HEAD
rcu-tasks.2014.09.10a: Add RCU-tasks flavor of RCU.
2014-09-16 10:10:44 -07:00
Paul E. McKenney
69c604557c rcutorture: Add torture tests for RCU-tasks
This commit adds torture tests for RCU-tasks.  It also fixes a bug that
would segfault for an RCU flavor lacking a callback-barrier function.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-09-07 16:27:24 -07:00
Paul E. McKenney
bde6c3aa99 rcu: Provide cond_resched_rcu_qs() to force quiescent states in long loops
RCU-tasks requires the occasional voluntary context switch
from CPU-bound in-kernel tasks.  In some cases, this requires
instrumenting cond_resched().  However, there is some reluctance
to countenance unconditionally instrumenting cond_resched() (see
http://lwn.net/Articles/603252/), so this commit creates a separate
cond_resched_rcu_qs() that may be used in place of cond_resched() in
locations prone to long-duration in-kernel looping.

This commit currently instruments only RCU-tasks.  Future possibilities
include also instrumenting RCU, RCU-bh, and RCU-sched in order to reduce
IPI usage.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:20 -07:00
Paul E. McKenney
38706bc5a2 rcutorture: Add callback-flood test
Although RCU is designed to handle arbitrary floods of callbacks, this
capability is not routinely tested.   This commit therefore adds a
cbflood capability in which kthreads repeatedly registers large numbers
of callbacks.  One such kthread is created for each four CPUs (rounding
up), and the test may be controlled by several cbflood_* kernel boot
parameters, which control the number of bursts per flood, the number
of callbacks per burst, the time between bursts, and the time between
floods.  The default values are large enough to exercise RCU's emergency
responses to callback flooding.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: David Miller <davem@davemloft.net>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
2014-09-07 16:24:48 -07:00
Joe Perches
eea203fea3 rcu: Use pr_alert/pr_cont for printing logs
User pr_alert/pr_cont for printing the logs from rcutorture module directly
instead of writing it to a buffer and then printing it. This allows us from not
having to allocate such buffers. Also remove a resulting empty function.

I tested this using the parse-torture.sh script as follows:

$ dmesg | grep torture > log.txt
$ bash parse-torture.sh log.txt test
$

There were no warnings which means that parsing went fine.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:24:47 -07:00
Pranith Kumar
58ade2dbe9 rcutorture: Fix a sparse warning by marking boost_mutex static
This commit fixes the following sparse warning by marking boost_mutex
static:

kernel/rcu/rcutorture.c:185:1: warning: symbol 'boost_mutex' was not declared. Should it be static?

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-09-07 16:24:17 -07:00
Josh Triplett
e0198b290d Josh has moved
My IBM email addresses haven't worked for years; also map some
old-but-functional forwarding addresses to my canonical address.

Update my GPG key fingerprint; I moved to 4096R a long time ago.

Update description.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-07-30 17:16:13 -07:00
Paul E. McKenney
5228084eed torture: Check for multiple concurrent torture tests
The torture tests are designed to run in isolation, but do not enforce
this isolation.  This commit therefore checks for concurrent torture
tests, and refuses to start new tests while old tests are running.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-05-14 09:46:29 -07:00
Paul E. McKenney
48d684fdad rcutorture: Run rcu_torture_writer at normal priority
There are usually lots of readers and only one writer, so if there has
to be a choice, we would want rcu_torture_writer to win.  This commit
therefore removes the set_user_nice() from rcu_torture_writer().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-05-14 09:46:26 -07:00
Thomas Gleixner
424c1b6820 rcutorture: Add missing destroy_timer_on_stack()
The rcu_torture_reader() function uses an on-stack timer_list structure
which it initializes with setup_timer_on_stack().  However, it fails to
use destroy_timer_on_stack() before exiting, which results in leaking a
tracking object if DEBUG_OBJECTS is enabled.  This commit therefore
invokes destroy_timer_on_stack() to avoid this leakage.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-05-14 09:46:24 -07:00
Paul E. McKenney
f0bf8fab4f rcutorture: Explicitly test synchronous grace-period primitives
The original rcu_torture_writer() avoided testing the synchronous
grace-period primitives because they were simply wrappers around
call_rcu() invocations.  The testing of these synchronous primitives
was delegated to the fake writers.  However, there really is no excuse
not to test them, especially in the case of SRCU, where the wrappering
is somewhat more elaborate.  This commit therefore makes the default
rcutorture parameters cause rcu_torture_writer() to include synchronous
grace-period primitives in its testing.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-05-14 09:46:22 -07:00
Paul E. McKenney
a48f3fad4f rcutorture: Add tests for get_state_synchronize_rcu()
This commit adds rcutorture testing for get_state_synchronize_rcu()
and cond_synchronize_rcu().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-05-14 09:46:21 -07:00
Paul E. McKenney
d0d0606e2c rcutorture: Check for rcu_torture_fqs creation errors
The return value from torture_create_kthread() is currently ignored
when creating the rcu_torture_fqs kthread.  This commit therefore
captures the return value so that it can be tested for errors.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-05-14 09:46:17 -07:00
Paul E. McKenney
64e4b43ae0 rcutorture: Make rcu_torture_reader() use cond_resched()
The rcu_torture_reader() function currently uses schedule().  This commit
therefore speeds things up a bit by substituting cond_resched().
This change makes rcu_torture_reader() more CPU-bound, so this commit
also adjusts the number of readers (the "nreaders" module parameter,
which feeds into the "nrealreaders" variable) to allow one CPU to be
free of readers on SMP systems.  The point of this is to increase the
probability that readers will be watching while an updater makes a change.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-05-14 09:46:13 -07:00
Paul E. McKenney
afea227fd4 rcutorture: Export RCU grace-period kthread wait state to rcutorture
This commit allows rcutorture to print additional state for the
RCU grace-period kthreads in cases where RCU seems reluctant to
start a new grace period.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-05-14 09:46:09 -07:00
Paul E. McKenney
945fa9c631 torture: Dump ftrace buffer when the RCU grace period stalls
This commit adds a call to rcutorture_trace_dump() to dump the ftrace
buffer when the RCU grace period stalls in order to help debug the
stall.  Note that this is different than the RCU CPU stall warning,
as it is rcutorture detecting the stall rather than the underlying RCU
implementation.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-05-14 09:46:07 -07:00
Paul E. McKenney
589a8f5950 rcutorture: Print negatives for SRCU counter wraparound
The srcu_torture_stats() function prints SRCU's per-CPU c[] array with
an unsigned format, which means that the number one less than zero is
a very large number.  This commit therefore prints this array with a
signed format in order to improve readability of the rcutorture output.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-05-14 09:45:58 -07:00
Rashika Kheria
b3b8a4d42b rcutorture: Mark function as static in kernel/rcu/torture.c
Mark functions as static in kernel/rcu/torture.c because they are not
used outside this file.

This eliminates the following warning in kernel/rcu/torture.c:
kernel/rcu/torture.c:902:6: warning: no previous prototype for ‘rcutorture_trace_dump’ [-Wmissing-prototypes]
kernel/rcu/torture.c:1572:6: warning: no previous prototype for ‘rcu_torture_barrier_cbf’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-05-14 09:45:53 -07:00
Paul E. McKenney
ad0dc7f94d rcutorture: Add forward-progress checking for writer
The rcutorture output currently does not distinguish between stalls in
the RCU implementation and stalls in the rcu_torture_writer() kthreads.
This commit therefore adds some diagnostics to help distinguish between
these two conditions, at least for the non-SRCU implementations.  (SRCU
does not provide evidence of update-side forward progress by design.)

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-05-13 11:18:18 -07:00
Linus Torvalds
971eae7c99 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler changes from Ingo Molnar:
 "Bigger changes:

   - sched/idle restructuring: they are WIP preparation for deeper
     integration between the scheduler and idle state selection, by
     Nicolas Pitre.

   - add NUMA scheduling pseudo-interleaving, by Rik van Riel.

   - optimize cgroup context switches, by Peter Zijlstra.

   - RT scheduling enhancements, by Thomas Gleixner.

  The rest is smaller changes, non-urgnt fixes and cleanups"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (68 commits)
  sched: Clean up the task_hot() function
  sched: Remove double calculation in fix_small_imbalance()
  sched: Fix broken setscheduler()
  sparc64, sched: Remove unused sparc64_multi_core
  sched: Remove unused mc_capable() and smt_capable()
  sched/numa: Move task_numa_free() to __put_task_struct()
  sched/fair: Fix endless loop in idle_balance()
  sched/core: Fix endless loop in pick_next_task()
  sched/fair: Push down check for high priority class task into idle_balance()
  sched/rt: Fix picking RT and DL tasks from empty queue
  trace: Replace hardcoding of 19 with MAX_NICE
  sched: Guarantee task priority in pick_next_task()
  sched/idle: Remove stale old file
  sched: Put rq's sched_avg under CONFIG_FAIR_GROUP_SCHED
  cpuidle/arm64: Remove redundant cpuidle_idle_call()
  cpuidle/powernv: Remove redundant cpuidle_idle_call()
  sched, nohz: Exclude isolated cores from load balancing
  sched: Fix select_task_rq_fair() description comments
  workqueue: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICE
  sys: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICE
  ...
2014-03-31 11:21:19 -07:00
Paul E. McKenney
f5604f67fe Merge branch 'torture.2014.02.23a' into HEAD
torture.2014.02.23a: locktorture addition and rcutorture changes
2014-02-26 06:38:59 -08:00
Paul E. McKenney
ff20e251c4 rcutorture: Add an rcu_busted to test the test
This commit adds a deliberately buggy RCU implementation into rcutorture
to allow easy checking that rcutorture correctly flags buggy RCU
implementations.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:04:30 -08:00
Paul E. McKenney
bfefc73aa1 rcutorture: Stop generic kthreads in torture_cleanup()
The specific torture modules (like rcutorture) need to call
torture_cleanup() in any case, so this commit makes torture_cleanup()
deal with torture_shutdown_cleanup() and torture_stutter_cleanup() so
that the specific modules don't have to deal with these details.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:04:27 -08:00
Paul E. McKenney
9c029b8609 rcutorture: Abstract torture_stop_kthread()
Stopping of kthreads is not RCU-specific, so this commit abstracts
out torture_stop_kthread(), saving a few lines of code in the process.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:04:25 -08:00
Paul E. McKenney
47cf29b9e7 rcutorture: Abstract torture_create_kthread()
Creation of kthreads is not RCU-specific, so this commit abstracts
out torture_create_kthread(), saving a few tens of lines of code in
the process.

This change requires modifying VERBOSE_TOROUT_ERRSTRING() to take a
non-const string, so that _torture_create_kthread() can avoid an
open-coded substitute.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:03:24 -08:00
Paul E. McKenney
bc8f83e2c0 rcutorture: Fix missing-return bug in rcu_torture_barrier_init()
This commit adds a missing error return to the code path that creates
the rcu_torture_barrier() kthread.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:03:22 -08:00
Paul E. McKenney
7fafaac5b9 rcutorture: Fix rcutorture shutdown races
Not all of the rcutorture kthreads waited for kthread_should_stop()
before returning from their top-level functions, and none of them
used torture_shutdown_absorb() properly.  These problems can result in
segfaults and hangs at shutdown time, and some recent changes perturbed
timing sufficiently to make them much more probable.  This commit
therefore creates a torture_kthread_stopping() function that does the
proper kthread shutdown dance in one centralized location.

Accommodate this grouping by making VERBOSE_TOROUT_STRING() capable of
taking a non-const string as its argument, which allows the new
torture_kthread_stopping() to pass its "title" argument directly to
the updated version of VERBOSE_TOROUT_STRING().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-02-23 09:03:21 -08:00
Paul E. McKenney
14562d1cf1 rcutorture: Announce task creation
A few "stealth-start rcutorture kthreads" have accumulated over the years,
so this commit adds console-log announcements (but only if the torture
tests are running verbose).

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:03:20 -08:00
Paul E. McKenney
01025ebc99 rcutorture: Clean up rcu_torture_init() error checking
This commit applies some simple cleanups to rcu_torture_init() error
checking.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:03:19 -08:00
Paul E. McKenney
e991dbc077 rcutorture: Abstract torture_shutdown()
Because auto-shutdown of torture testing is not specific to RCU,
this commit moves the auto-shutdown function to kernel/torture.c.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:03:18 -08:00
Paul E. McKenney
628edaa506 rcutorture: Abstract stutter_wait()
Because stuttering the test load (stopping and restarting it) is useful
for non-RCU testing, this commit moves the load-stuttering functionality
to kernel/torture.c.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:02:54 -08:00
Paul E. McKenney
36970bb91d rcutorture: Privatize fullstop
This commit introduces the torture_must_stop() function in order to
keep use of the fullstop variable local to kernel/torture.c.  There
is also a torture_must_stop_irq() counterpart for use from RCU callbacks,
timeout handlers, and the like.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:01:12 -08:00
Paul E. McKenney
4622b487ec rcutorture: Abstract torture_shutdown_notify()
Because handling the race between rmmod and system shutdown is not
specific to RCU, this commit abstracts torture_shutdown_notify(),
placing this code into kernel/torture.c.  This change also allows
fullstop_mutex to be private to kernel/torture.c.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:01:11 -08:00
Paul E. McKenney
cc47ae0830 rcutorture: Abstract torture-test cleanup
This commit creates a torture_cleanup() that handles the generic
cleanup actions local to kernel/torture.c.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:01:08 -08:00
Paul E. McKenney
b5daa8f3b3 rcutorture: Abstract torture-test initialization
This commit creates torture_init_begin() and torture_init_end() functions
to abstract locking and allow the torture_type and verbose variables
in kernel/torture.o to become static.  With a bit more abstraction,
fullstop_mutex will also become static.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:01:07 -08:00
Paul E. McKenney
2e9e8081d2 rcutorture: Abstract torture_onoff()
Because online/offline torturing is not specific to RCU, this commit
abstracts it into the kernel/torture.c module to allow other torture
tests to use it.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:01:06 -08:00
Paul E. McKenney
3808dc9fab rcutorture: Abstract torture_shuffle()
The torture_shuffle() function forces each CPU in turn to go idle
periodically in order to check for problems interacting with per-CPU
variables and with dyntick-idle mode.  Because this sort of debugging
is not specific to RCU, this commit abstracts that functionality.
This in turn requires abstracting some additional infrastructure.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:01:05 -08:00
Paul E. McKenney
f67a33561e rcutorture: Abstract torture_shutdown_absorb()
Because handling races between rmmod and normal shutdown is not specific
to rcutorture, this commit renames rcutorture_shutdown_absorb() to
torture_shutdown_absorb() and pulls it out into then kernel/torture.c
module.  This implies pulling the fullstop mechanism into kernel/torture.c
as well.

The exporting of fullstop and fullstop_mutex is ugly and must die.
And it does in fact die in later commits that introduce higher-level
APIs that encapsulate both of these variables.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>`
2014-02-23 09:01:04 -08:00
Paul E. McKenney
c2884de38e rcutorture: Abstract TOROUT_STRING() and friends
These diagnostic macros are not confined to torturing RCU, so this commit
makes them available to other torture tests.  Also removed the do-while
from TOROUT_STRING() in response to checkpatch complaints.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-02-23 09:01:02 -08:00
Paul E. McKenney
5ccf60f23d rcutorture: Rename PRINTK to TOROUT
Since it doesn't do printk()s anymore anyway, this commit renames these
macros from PRINTK to TOROUT (short for torture output).

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23 09:01:01 -08:00
Paul E. McKenney
9e25022541 rcutorture: Abstract torture_param()
Create a torture_param() macro and apply it to rcutorture in order to
save a few lines of code.  This same macro may be applied to other
torture frameworks.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-02-23 09:01:00 -08:00
Paul E. McKenney
51b1130eb5 rcutorture: Abstract rcu_torture_random()
Because rcu_torture_random() will be used by the locking equivalent to
rcutorture, pull it out into its own module.  This new module cannot
be separately configured, instead, use the Kconfig "select" statement
from the Kconfig options of tests depending on it.

Suggested-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-02-23 09:00:58 -08:00