Commit Graph

274 Commits

Author SHA1 Message Date
Paul E. McKenney
063f5a4df9 rcutorture: Don't count CPU-stalled time against priority boosting
It will frequently be the case that rcu_torture_boost() will get a
->start_gp_poll() cookie that needs almost all of the current grace period
plus an additional grace period to elapse before ->poll_gp_state() will
return true.  It is quite possible that the current grace period will have
(say) two seconds of stall by a CPU failing to pass through a quiescent
state, followed by 300 milliseconds of delay due to a preempted reader.
The next grace period might suffer only one second of stall by a CPU,
followed by another 300 milliseconds of delay due to a preempted reader.
This is an example of RCU priority boosting doing its job, but the full
elapsed time of 3.6 seconds exceeds the 3.5-second limit.  In addition,
there is no CPU stall in force at the 3.5-second mark, so this would
nevertheless currently be counted as an RCU priority boosting failure.

This commit therefore avoids this sort of false positive by resetting
the gp_state_time timestamp any time that the current grace period is
being blocked by a CPU.  This results in extremely frequent calls to
the ->check_boost_failed() function, so this commit provides a lockless
fastpath that is selected by supplying a NULL CPU-number pointer.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10 16:05:07 -07:00
Paul E. McKenney
0260b92e1c rcutorture: Forgive RCU boost failures when CPUs don't pass through QS
Currently, rcu_torture_boost() runs CPU-bound at real-time priority
to force RCU priority inversions.  It then checks that grace periods
progress during this CPU-bound time.  If grace periods fail to progress,
it reports and RCU priority boosting failure.

However, it is possible (and sometimes does happen) that the grace period
fails to progress due to a CPU failing to pass through a quiescent state
for an extended time period (3.5 seconds by default).  This can happen
due to vCPU preemption, long-running interrupts, and much else besides.
There is nothing that RCU priority boosting can do about these situations,
and so they should not be counted as RCU priority boosting failures.

This commit therefore checks for CPUs (as opposed to preempted tasks)
holding up a grace period, and flags the resulting RCU priority boosting
failures, but does not splat nor count them as errors.  It does rate-limit
them to avoid flooding the console log.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10 16:05:07 -07:00
Paul E. McKenney
bcd4af44e2 rcutorture: Make rcu_torture_boost_failed() check for GP end
It is possible that a delayed grace period that rcu_torture_boost()
was polling for ended while rcu_torture_boost_failed() was printing the
failure splat.  It would be good to know when this happens.  This commit
therefore has rcu_torture_boost_failed() recheck the grace period after
printing the splat, and printing a message indicating whether or not
the grace period has ended.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10 16:05:06 -07:00
Paul E. McKenney
8c7ec02e2a rcutorture: Consolidate rcu_torture_boost() timing and statistics
This commit consolidates two loops in rcu_torture_boost(), one of which
counts the number of boost-test episodes and the other of which computes
the start time of the next episode, into one loop that does both with but
a single acquisition of boost_mutex.  This means that the count of the
number of boost-test episodes is incremented after an episode completes
rather than before it starts, but it also avoids the over-counting that
was possible previously.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10 16:05:06 -07:00
Paul E. McKenney
7b9dad7aba rcutorture: Delay-based false positives for RCU priority boosting tests
If an rcu_torture_boost() kthread determines that its grace period
has not yet ended, it invokes rcu_torture_boost_failed() which checks
whether enough time has elapsed for this to be considered a failure of
RCU priority boosting, and, if so, flags the error.

Unfortunately, that kthread might be preempted for some seconds between
the time that it checks the grace period and the time that it checks the
time.  This delay can result in a false positive, featuring a complaint
that a particular grace period has not ended, followed by a diagnostic
dump featuring a much later grace period.

This commit avoids these false positives by rechecking for the end of
the grace period after the time check.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10 16:05:06 -07:00
Paul E. McKenney
ea6d962e80 rcutorture: Judge RCU priority boosting on grace periods, not callbacks
Currently, rcutorture's testing of RCU priority boosting insists not
only that grace periods complete, but also that callbacks be invoked.
Although this is in fact what the user would want, ensuring that there
is sufficient CPU bandwidth devoted to callback execution is in fact
the user's responsibility.  One could argue that rcutorture can take on
that responsibility, which is true in theory.  But in practice, ensuring
sufficient CPU bandwidth to ksoftirqd, any rcuc kthreads, and any rcuo
kthreads is not particularly consistent with rcutorture's main job,
that of stress-testing RCU.  In addition, if the system administrator
(say) makes very poor choices when pinning rcuo kthreads and then runs
rcutorture, there really isn't much rcutorture can do.

Besides, RCU priority boosting only boosts lagging readers, not all the
machinery required to invoke callbacks in a timely fashion.

This commit therefore switches rcutorture's evaluation of RCU priority
boosting from callback execution to grace-period completion by using
the new start_poll_synchronize_rcu() and poll_state_synchronize_rcu()
functions.  When rcutorture is built in (as in when there is no innocent
workload to inconvenience), the ksoftirqd ktheads are boosted to real-time
priority 2 in order to allow timeouts to work properly in the face of
rcutorture's testing of RCU priority boosting.

Indeed, it is not as easy as it looks to create a reliable test of RCU
priority boosting without destroying the rest of the kernel!

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10 16:05:06 -07:00
Paul E. McKenney
a5c095e0e9 rcutorture: Abstract read-lock-held checks
This commit adds a (*readlock_held)() function pointer to the
rcu_torture_ops structure in order to make the rcu_torture_one_read()
function's rcu_dereference_check() lockdep expression more appropriate
for a given run.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10 16:05:05 -07:00
Paul E. McKenney
ab6ad3dbdd Merge branches 'bitmaprange.2021.03.08a', 'fixes.2021.03.15a', 'kvfree_rcu.2021.03.08a', 'mmdumpobj.2021.03.08a', 'nocb.2021.03.15a', 'poll.2021.03.24a', 'rt.2021.03.08a', 'tasks.2021.03.08a', 'torture.2021.03.08a' and 'torturescript.2021.03.22a' into HEAD
bitmaprange.2021.03.08a:  Allow 3-N for bitmap ranges.
fixes.2021.03.15a:  Miscellaneous fixes.
kvfree_rcu.2021.03.08a:  kvfree_rcu() updates.
mmdumpobj.2021.03.08a:  mem_dump_obj() updates.
nocb.2021.03.15a:  RCU NOCB CPU updates, including limited deoffloading.
poll.2021.03.24a:  Polling grace-period interfaces for RCU.
rt.2021.03.08a:  Realtime-related RCU changes.
tasks.2021.03.08a:  Tasks-RCU updates.
torture.2021.03.08a:  Torture-test updates.
torturescript.2021.03.22a:  Torture-test scripting updates.
2021-03-24 17:20:18 -07:00
Paul E. McKenney
7ac3fdf099 rcutorture: Test start_poll_synchronize_rcu() and poll_state_synchronize_rcu()
This commit causes rcutorture to test the new start_poll_synchronize_rcu()
and poll_state_synchronize_rcu() functions.  Because of the difficulty of
determining the nature of a synchronous RCU grace (expedited or not),
the test that insisted that poll_state_synchronize_rcu() detect an
intervening synchronize_rcu() had to be dropped.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-03-24 17:17:38 -07:00
Stephen Zhang
0a27fff30a rcutorture: Replace rcu_torture_stall string with %s
This commit replaces a hard-coded "rcu_torture_stall" string in a
pr_alert() format with "%s" and __func__.

Signed-off-by: Stephen Zhang <stephenzhangzsd@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-03-08 14:22:28 -08:00
Paul E. McKenney
5e59fba573 rcutorture: Fix testing of RCU priority boosting
Currently, rcutorture refuses to test RCU priority boosting in
CONFIG_HOTPLUG_CPU=y kernels, which are the only kind normally built on
x86 these days.  This commit therefore updates rcutorture's tests of RCU
priority boosting to make them safe for CPU hotplug.  However, these tests
will fail unless TIMER_SOFTIRQ runs at realtime priority, which does not
happen in current mainline.  This commit therefore also refuses to test
RCU priority boosting except in kernels built with CONFIG_PREEMPT_RT=y.

While in the area, this commt adds some debug output at boost-fail time
that helps diagnose the cause of the failure, for example, failing to
run TIMER_SOFTIRQ at realtime priority.

Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Scott Wood <swood@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-03-08 14:21:41 -08:00
Paul E. McKenney
0d3dd2c8ea rcutorture: Add crude tests for mem_dump_obj()
This commit adds a few crude tests for mem_dump_obj() to rcutorture
runs.  Just to prevent bitrot, you understand!

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-03-08 14:18:46 -08:00
Paul E. McKenney
0d2460ba61 Merge branches 'doc.2021.01.06a', 'fixes.2021.01.04b', 'kfree_rcu.2021.01.04a', 'mmdumpobj.2021.01.22a', 'nocb.2021.01.06a', 'rt.2021.01.04a', 'stall.2021.01.06a', 'torture.2021.01.12a' and 'tortureall.2021.01.06a' into HEAD
doc.2021.01.06a: Documentation updates.
fixes.2021.01.04b: Miscellaneous fixes.
kfree_rcu.2021.01.04a: kfree_rcu() updates.
mmdumpobj.2021.01.22a: Dump allocation point for memory blocks.
nocb.2021.01.06a: RCU callback offload updates and cblist segment lengths.
rt.2021.01.04a: Real-time updates.
stall.2021.01.06a: RCU CPU stall warning updates.
torture.2021.01.12a: Torture-test updates and polling SRCU grace-period API.
tortureall.2021.01.06a: Torture-test script updates.
2021-01-22 15:26:44 -08:00
Paul E. McKenney
1afb95fee0 torture: Maintain torture-specific set of CPUs-online books
The TREE01 rcutorture scenario intentionally creates confusion as to the
number of available CPUs by specifying the "maxcpus=8 nr_cpus=43" kernel
boot parameters.  This can disable rcutorture's load shedding, which
currently uses num_online_cpus(), which would count the extra 35 CPUs.
However, the rcutorture guest OS will be provisioned with only 8 CPUs,
which means that rcutorture will present full load even when all but one
of the original 8 CPUs are offline.  This can result in spurious errors
due to extreme overloading of that single remaining CPU.

This commit therefore keeps a separate set of books on the number of
usable online CPUs, so that torture_num_online_cpus() is used for load
shedding instead of num_online_cpus().  Note that initial sizing must
use num_online_cpus() because torture_num_online_cpus() will return
NR_CPUS until shortly after torture_onoff_init() is invoked.

Reported-by: Frederic Weisbecker <frederic@kernel.org>
[ paulmck: Apply feedback from kernel test robot. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06 17:17:22 -08:00
Paul E. McKenney
edf7b84178 rcutorture: Make object_debug also double call_rcu() heap object
This commit provides a test for call_rcu() printing the allocation address
of a double-freed callback by double-freeing a callback allocated via
kmalloc().  However, this commit does not depend on any other commit.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06 17:17:21 -08:00
Paul E. McKenney
1eba0ef981 rcutorture: Use hrtimers for reader and writer delays
This commit replaces schedule_timeout_uninterruptible() and
schedule_timeout_interruptible() with torture_hrtimeout_us() and
torture_hrtimeout_jiffies() to avoid timer-wheel synchronization.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06 17:17:20 -08:00
Paul E. McKenney
ea31fd9ca8 rcutorture: Use torture_hrtimeout_jiffies() to avoid busy-waits
Because rcu_torture_writer() and rcu_torture_fakewriter() predate
hrtimers, they do timer-wheel-decoupled timed waits by using the
timer-wheel-based schedule_timeout_interruptible() functions in
conjunction with a random udelay()-based wait.  This latter unnecessarily
burns CPU time, so this commit instead uses torture_hrtimeout_jiffies()
to decouple from the timer wheels without busy-waiting.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06 17:17:19 -08:00
Paul E. McKenney
682189a3f8 rcutorture: Make rcu_torture_fakewriter() use blocking wait primitives
Full testing of the new SRCU polling API requires that the fake
writers also use it in order to test concurrent calls to all of the API
members, especially start_poll_synchronize_srcu().  This commit makes
rcu_torture_fakewriter() use all available blocking grace-period-wait
primitives available from the RCU flavor under test.

Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06 17:17:18 -08:00
Paul E. McKenney
18fbf307b7 rcutorture: Make synctype[] and nsynctype be static global
Full testing of the new SRCU polling API requires that the fake writers
also use it in order to test concurrent calls to all of the API members,
especially start_poll_synchronize_srcu().  This commit prepares the ground
for this by making the synctype[] and nsynctype variables be static
globals so that the rcu_torture_fakewriter() function can access them.
Initialization of these variables is moved from rcu_torture_writer()
to a new rcu_torture_write_types() function that is invoked from
rcu_torture_init() just before the first writer kthread is spawned.

Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06 17:17:10 -08:00
Paul E. McKenney
12a910e3cd rcutorture: Require entire stutter period be post-boot
Currently, the rcu_torture_writer() function checks that all required
grace periods elapse during a stutter interval, which is a multi-second
time period during which the test load is removed.  However, this check
is suppressed during early boot (that is, before init is spawned) in
order to avoid false positives that otherwise occur due to heavy load
on the single boot CPU.

Unfortunately, this approach is insufficient.  It is possible that the
stutter interval might end just as init is spawned, so that early boot
conditions prevailed during almost the entire stutter interval.

This commit therefore takes a snapshot of boot-complete state just
before the stutter interval, thus suppressing the check for failure to
complete grace periods unless the entire stutter interval took place
after early boot.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06 17:08:12 -08:00
Paul E. McKenney
f759081e8f rcu/nocb: Code-style nits in callback-offloading toggling
This commit addresses a few code-style nits in callback-offloading
toggling, including one that predates this toggling.

Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06 16:47:55 -08:00
Paul E. McKenney
2c4319bd1d rcutorture: Test runtime toggling of CPUs' callback offloading
Frederic Weisbecker is adding the ability to change the rcu_nocbs state
of CPUs at runtime, that is, to offload and deoffload their RCU callback
processing without the need to reboot.  As the old saying goes, "if it
ain't tested, it don't work", so this commit therefore adds prototype
rcutorture testing for this capability.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
2021-01-06 16:24:59 -08:00
Paul E. McKenney
00504537f4 rcutorture: Add testing for RCU's global memory ordering
RCU guarantees that anything seen by a given reader will also be seen
after any grace period that must wait on that reader.  This is very likely
to hold based on inspection, but the advantage of having rcutorture do
the inspecting is that rcutorture doesn't mind inspecting frequently
and often.

This commit therefore adds code to test RCU's global memory ordering.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-04 13:53:41 -08:00
Paul E. McKenney
bc480a6354 rcutorture: Add reader-side tests of polling grace-period API
This commit adds reader-side testing of the polling grace-period API.
This testing verifies that a cookie obtained in an SRCU read-side critical
section does not get a true return from poll_state_synchronize_srcu()
within that same critical section.

Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-04 13:53:40 -08:00
Paul E. McKenney
0fd0548db1 rcutorture: Add writer-side tests of polling grace-period API
This commit adds writer-side testing of the polling grace-period API.
One test verifies that the polling API sees a grace period caused by
some other mechanism.  Another test verifies that using the polling API
to wait for a grace period does not result in too-short grace periods.
A third test verifies that the polling API does not report
completion within a read-side critical section.  A fourth and final
test verifies that the polling API does report completion given an
intervening grace period.

Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-04 13:53:40 -08:00
Paul E. McKenney
fd56f64b4e rcutorture: Prepare for ->start_gp_poll and ->poll_gp_state
The new get_state_synchronize_srcu(), start_poll_synchronize_srcu() and
poll_state_synchronize_srcu() functions need to be tested, and so this
commit prepares by renaming the rcu_torture_ops field ->get_state to
->get_gp_state in order to be consistent with the upcoming ->start_gp_poll
and ->poll_gp_state fields.

Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-04 13:53:39 -08:00
Paul E. McKenney
7fc91fc845 Merge branches 'cpuinfo.2020.11.06a', 'doc.2020.11.06a', 'fixes.2020.11.19b', 'lockdep.2020.11.02a', 'tasks.2020.11.06a' and 'torture.2020.11.06a' into HEAD
cpuinfo.2020.11.06a: Speedups for /proc/cpuinfo.
doc.2020.11.06a: Documentation updates.
fixes.2020.11.19b: Miscellaneous fixes.
lockdep.2020.11.02a: Lockdep-RCU updates to avoid "unused variable".
tasks.2020.11.06a: Tasks-RCU updates.
torture.2020.11.06a': Torture-test updates.
2020-11-19 19:37:47 -08:00
Paul E. McKenney
a7eb937b67 rcutorture: Don't do need_resched() testing if ->sync is NULL
If cur_ops->sync is NULL, rcu_torture_fwd_prog_nr() will nevertheless
attempt to call through it.  This commit therefore flags cases where
neither need_resched() nor call_rcu() forward-progress testing
can be performed due to NULL function pointers, and also causes
rcu_torture_fwd_prog_nr() to take an early exit if cur_ops->sync()
is NULL.

Reported-by: Tom Rix <trix@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-06 17:13:57 -08:00
Paul E. McKenney
293b93d66f rcutorture: Small code cleanups
The rcu_torture_cleanup() function fails to NULL out the reader_tasks
pointer after freeing it and its fakewriter_tasks loop has redundant
braces.  This commit therefore cleans these up.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-06 17:13:55 -08:00
Paul E. McKenney
ab1b7880de rcutorture: Make stutter_wait() caller restore priority
Currently, stutter_wait() will happily spin waiting for the stutter
interval to end even if the caller is running at a real-time priority
level.  This could starve normal-priority tasks for no good reason.  This
commit therefore drops the calling task's priority to SCHED_OTHER MAX_NICE
if stutter_wait() needs to wait.  But when it waits, stutter_wait()
returns true, which allows the caller to restore the priority if needed.
Callers that were already running at SCHED_OTHER MAX_NICE obviously
do not need any changes, but this commit also restores priority for
higher-priority callers.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-06 17:13:54 -08:00
Paul E. McKenney
4994684ce1 rcutorture: Prevent hangs for invalid arguments
If an rcutorture torture-test run is given a bad kvm.sh argument, the
test will complain to the console, which is good.  What is bad is that
from the user's perspective, it will just hang for the time specified
by the --duration argument.  This commit therefore forces an immediate
kernel shutdown if a rcu_torture_init()-time error occurs, thus avoiding
the appearance of a hang.  It also forces a console splat in this case
to clearly indicate the presence of an error.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-06 17:13:53 -08:00
Paul E. McKenney
27c0f14483 rcutorture: Make grace-period kthread report match RCU flavor being tested
At the end of the test and after rcu_torture_writer() stalls, rcutorture
invokes show_rcu_gp_kthreads() in order to dump out information on the
RCU grace-period kthread.  This makes a lot of sense when testing vanilla
RCU, but not so much for the other flavors.  This commit therefore allows
per-flavor kthread-dump functions to be specified.

[ paulmck: Apply feedback from kernel test robot <lkp@intel.com>. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-02 17:12:43 -08:00
Paul E. McKenney
d685514260 rcutorture: Allow pointer leaks to test diagnostic code
This commit adds an rcutorture.leakpointer module parameter that
intentionally leaks an RCU-protected pointer out of the RCU read-side
critical section and checks to see if the corresponding grace period
has elapsed, emitting a WARN_ON_ONCE() if so.  This module parameter can
be used to test facilities like CONFIG_RCU_STRICT_GRACE_PERIOD that end
grace periods quickly.

While in the area, also document rcutorture.irqreader, which was
previously left out.

Reported-by Jann Horn <jannh@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:36 -07:00
Paul E. McKenney
299c7d94f6 rcutorture: Hoist OOM registry up one level
Currently, registering and unregistering the OOM notifier is done
right before and after the test, respectively.  This will not work
well for multi-threaded tests, so this commit hoists this registering
and unregistering up into the rcu_torture_fwd_prog_init() and
rcu_torture_fwd_prog_cleanup() functions.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:35 -07:00
Paul E. McKenney
57f602022e rcutorture: Properly synchronize with OOM notifier
The current rcutorture forward-progress code assumes that it is the
only cause of out-of-memory (OOM) events.  For script-based rcutorture
testing, this assumption is in fact correct.  However, testing based
on modprobe/rmmod might well encounter external OOM events, which could
happen at any time.

This commit therefore properly synchronizes the interaction between
rcutorture's forward-progress testing and its OOM notifier by adding a
global mutex.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:34 -07:00
Paul E. McKenney
c8fa637147 rcutorture: Properly set rcu_fwds for OOM handling
The conversion of rcu_fwds to dynamic allocation failed to actually
allocate the required structure.  This commit therefore allocates it,
frees it, and updates rcu_fwds accordingly.  While in the area, it
abstracts the cleanup actions into rcu_torture_fwd_prog_cleanup().

Fixes: 5155be9994 ("rcutorture: Dynamically allocate rcu_fwds structure")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:34 -07:00
Joel Fernandes (Google)
959954df0c rcutorture: Output number of elapsed grace periods
This commit adds code to print the grace-period number at the start
of the test along with both the grace-period number and the number of
elapsed grace periods at the end of the test.  Note that variants of
RCU)without the notion of a grace-period number (for example, Tiny RCU)
just print zeroes.

[ paulmck: Adjust commit log. ]
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:31 -07:00
Paul E. McKenney
83224afd11 rcutorture: Remove KCSAN stubs
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 18:45:31 -07:00
Linus Torvalds
6d2b84a4e5 This tree adds the sched_set_fifo*() encapsulation APIs to remove
static priority level knowledge from non-scheduler code.
 
 The three APIs for non-scheduler code to set SCHED_FIFO are:
 
  - sched_set_fifo()
  - sched_set_fifo_low()
  - sched_set_normal()
 
 These are two FIFO priority levels: default (high), and a 'low' priority level,
 plus sched_set_normal() to set the policy back to non-SCHED_FIFO.
 
 Since the changes affect a lot of non-scheduler code, we kept this in a separate
 tree.
 
 When merging to the latest upstream tree there's a conflict in drivers/spi/spi.c,
 which can be resolved via:
 
 	sched_set_fifo(ctlr->kworker_task);
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAl8pPQIRHG1pbmdvQGtl
 cm5lbC5vcmcACgkQEnMQ0APhK1j0Jw/+LlSyX6gD2ATy3cizGL7DFPZogD5MVKTb
 IXbhXH/ACpuPQlBe1+haRLbJj6XfXqbOlAleVKt7eh+jZ1jYjC972RCSTO4566mJ
 0v8Iy9kkEeb2TDbYx1H3bnk78lf85t0CB+sCzyKUYFuTrXU04eRj7MtN3vAQyRQU
 xJg83x/sT5DGdDTP50sL7lpbwk3INWkD0aDCJEaO/a9yHElMsTZiZBKoXxN/s30o
 FsfzW56jqtng771H2bo8ERN7+abwJg10crQU5mIaLhacNMETuz0NZ/f8fY/fydCL
 Ju8HAdNKNXyphWkAOmixQuyYtWKe2/GfbHg8hld0jmpwxkOSTgZjY+pFcv7/w306
 g2l1TPOt8e1n5jbfnY3eig+9Kr8y0qHkXPfLfgRqKwMMaOqTTYixEzj+NdxEIRX9
 Kr7oFAv6VEFfXGSpb5L1qyjIGVgQ5/JE/p3OC3GHEsw5VKiy5yjhNLoSmSGzdS61
 1YurVvypSEUAn3DqTXgeGX76f0HH365fIKqmbFrUWxliF+YyflMhtrj2JFtejGzH
 Md3RgAzxusE9S6k3gw1ev4byh167bPBbY8jz0w3Gd7IBRKy9vo92h6ZRYIl6xeoC
 BU2To1IhCAydIr6hNsIiCSDTgiLbsYQzPuVVovUxNh+l1ZvKV2X+csEHhs8oW4pr
 4BRU7dKL2NE=
 =/7JH
 -----END PGP SIGNATURE-----

Merge tag 'sched-fifo-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull sched/fifo updates from Ingo Molnar:
 "This adds the sched_set_fifo*() encapsulation APIs to remove static
  priority level knowledge from non-scheduler code.

  The three APIs for non-scheduler code to set SCHED_FIFO are:

   - sched_set_fifo()
   - sched_set_fifo_low()
   - sched_set_normal()

  These are two FIFO priority levels: default (high), and a 'low'
  priority level, plus sched_set_normal() to set the policy back to
  non-SCHED_FIFO.

  Since the changes affect a lot of non-scheduler code, we kept this in
  a separate tree"

* tag 'sched-fifo-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  sched,tracing: Convert to sched_set_fifo()
  sched: Remove sched_set_*() return value
  sched: Remove sched_setscheduler*() EXPORTs
  sched,psi: Convert to sched_set_fifo_low()
  sched,rcutorture: Convert to sched_set_fifo_low()
  sched,rcuperf: Convert to sched_set_fifo_low()
  sched,locktorture: Convert to sched_set_fifo()
  sched,irq: Convert to sched_set_fifo()
  sched,watchdog: Convert to sched_set_fifo()
  sched,serial: Convert to sched_set_fifo()
  sched,powerclamp: Convert to sched_set_fifo()
  sched,ion: Convert to sched_set_normal()
  sched,powercap: Convert to sched_set_fifo*()
  sched,spi: Convert to sched_set_fifo*()
  sched,mmc: Convert to sched_set_fifo*()
  sched,ivtv: Convert to sched_set_fifo*()
  sched,drm/scheduler: Convert to sched_set_fifo*()
  sched,msm: Convert to sched_set_fifo*()
  sched,psci: Convert to sched_set_fifo*()
  sched,drbd: Convert to sched_set_fifo*()
  ...
2020-08-06 11:55:43 -07:00
Paul E. McKenney
13625c0a40 Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', 'kfree_rcu.2020.06.29a', 'rcu-tasks.2020.06.29a', 'scale.2020.06.29a', 'srcu.2020.06.29a' and 'torture.2020.06.29a' into HEAD
doc.2020.06.29a:  Documentation updates.
fixes.2020.06.29a:  Miscellaneous fixes.
kfree_rcu.2020.06.29a:  kfree_rcu() updates.
rcu-tasks.2020.06.29a:  RCU Tasks updates.
scale.2020.06.29a:  Read-side scalability tests.
srcu.2020.06.29a:  SRCU updates.
torture.2020.06.29a:  Torture-test updates.
2020-06-29 12:03:15 -07:00
Paul E. McKenney
7752275118 rcutorture: Check for unwatched readers
RCU is supposed to be watching all non-idle kernel code and also all
softirq handlers.  This commit adds some teeth to this statement by
adding a WARN_ON_ONCE().

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-29 12:01:44 -07:00
Jules Irenge
8f43d5911b rcu/rcutorture: Replace 0 with false
Coccinelle reports a warning

WARNING: Assignment of 0/1 to bool variable

The root cause is that the variable lastphase is a bool, but is
initialised with integer 0.  This commit therefore replaces the 0 with
a false.

Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-29 12:01:44 -07:00
Paul E. McKenney
cae7cc6ba5 rcutorture: NULL rcu_torture_current earlier in cleanup code
Currently, the rcu_torture_current variable remains non-NULL until after
all readers have stopped.  During this time, rcu_torture_stats_print()
will think that the test is still ongoing, which can result in confusing
dmesg output.  This commit therefore NULLs rcu_torture_current immediately
after the rcu_torture_writer() kthread has decided to stop, thus informing
rcu_torture_stats_print() much sooner.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-29 12:01:44 -07:00
Paul E. McKenney
4a5f133c15 rcutorture: Add races with task-exit processing
Several variants of Linux-kernel RCU interact with task-exit processing,
including preemptible RCU, Tasks RCU, and Tasks Trace RCU.  This commit
therefore adds testing of this interaction to rcutorture by adding
rcutorture.read_exit_burst and rcutorture.read_exit_delay kernel-boot
parameters.  These kernel parameters control the frequency and spacing
of special read-then-exit kthreads that are spawned.

[ paulmck: Apply feedback from Dan Carpenter's static checker. ]
[ paulmck: Reduce latency to avoid false-positive shutdown hangs. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-29 12:01:44 -07:00
Mauro Carvalho Chehab
43cb5451df docs: RCU: Convert torture.txt to ReST
- Add a SPDX header;
- Adjust document and section titles;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to RCU/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-29 11:58:11 -07:00
Peter Zijlstra
8b700983de sched: Remove sched_set_*() return value
Ingo suggested that since the new sched_set_*() functions are
implemented using the 'nocheck' variants, they really shouldn't ever
fail, so remove the return value.

Cc: axboe@kernel.dk
Cc: daniel.lezcano@linaro.org
Cc: sudeep.holla@arm.com
Cc: airlied@redhat.com
Cc: broonie@kernel.org
Cc: paulmck@kernel.org
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
2020-06-15 14:10:26 +02:00
Peter Zijlstra
ce1c8afd3f sched,rcutorture: Convert to sched_set_fifo_low()
Because SCHED_FIFO is a broken scheduler model (see previous patches)
take away the priority field, the kernel can't possibly make an
informed decision.

Effectively no change.

Cc: paulmck@kernel.org
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-15 14:10:25 +02:00
Paul E. McKenney
f736e0f1a5 Merge branches 'fixes.2020.04.27a', 'kfree_rcu.2020.04.27a', 'rcu-tasks.2020.04.27a', 'stall.2020.04.27a' and 'torture.2020.05.07a' into HEAD
fixes.2020.04.27a:  Miscellaneous fixes.
kfree_rcu.2020.04.27a:  Changes related to kfree_rcu().
rcu-tasks.2020.04.27a:  Addition of new RCU-tasks flavors.
stall.2020.04.27a:  RCU CPU stall-warning updates.
torture.2020.05.07a:  Torture-test updates.
2020-05-07 10:18:32 -07:00
Paul E. McKenney
3c80b40245 rcutorture: Convert ULONG_CMP_LT() to time_before()
This commit converts three ULONG_CMP_LT() invocations in rcutorture to
time_before() to reflect the fact that they are comparing timestamps to
the jiffies counter.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-05-07 10:15:29 -07:00
Jason Yan
afbc1574f1 rcutorture: Make rcu_fwds and rcu_fwd_emergency_stop static
This commit fixes the following sparse warning:

kernel/rcu/rcutorture.c:1695:16: warning: symbol 'rcu_fwds' was not declared. Should it be static?
kernel/rcu/rcutorture.c:1696:6: warning: symbol 'rcu_fwd_emergency_stop' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-05-07 10:15:29 -07:00