linux-toradex.git/include/linux/torture.h, branch v6.4-rc1

rcutorture: Call preempt_schedule() through static call/key

2022-04-12T00:07:29+00:00

The rcutorture test suite sometimess triggers a random scheduler
preemption call while simulating a read delay.  Unfortunately, its
direct call to preempt_schedule() bypasses the static call/key filter
used by CONFIG_PREEMPT_DYNAMIC.  This breaks the no-preempt assumption
when the dynamic preemption mode is "none".

For example, rcu_blocking_is_gp() is fooled and abbreviates grace periods
when the CPU runs in no-preempt UP mode.

Fix this by making torture_preempt_schedule() call __preempt_schedule(),
which uses the static call/key.

Reported-by: Paul E. McKenney 
Signed-off-by: Frederic Weisbecker 
Signed-off-by: Paul E. McKenney

locktorture,rcutorture,torture: Always log error message

2021-12-08T00:36:17+00:00

Unconditionally log messages corresponding to errors.

Acked-by: Davidlohr Bueso 
Signed-off-by: Li Zhijian 
Signed-off-by: Paul E. McKenney

rcutorture: Warn on individual rcu_torture_init() error conditions

2021-09-13T23:36:16+00:00

When running rcutorture as a module, any rcu_torture_init() issues will be
reflected in the error code from modprobe or insmod, as the case may be.
However, these error codes are not available when running rcutorture
built-in, for example, when using the kvm.sh script.  This commit
therefore adds WARN_ON_ONCE() to allow distinguishing rcu_torture_init()
errors when running rcutorture built-in.

Signed-off-by: Paul E. McKenney

torture: Maintain torture-specific set of CPUs-online books

2021-01-07T01:17:22+00:00

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 
[ paulmck: Apply feedback from kernel test robot. ]
Signed-off-by: Paul E. McKenney

torture: Throttle VERBOSE_TOROUT_*() output

2021-01-07T01:17:21+00:00

This commit adds kernel boot parameters torture.verbose_sleep_frequency
and torture.verbose_sleep_duration, which allow VERBOSE_TOROUT_*() output
to be throttled with periodic sleeps on large systems.

Signed-off-by: Paul E. McKenney

torture: Add fuzzed hrtimer-based sleep functions

2021-01-07T01:17:19+00:00

This commit adds torture_hrtimeout_ns(), torture_hrtimeout_us(),
torture_hrtimeout_ms(), torture_hrtimeout_jiffies(), and
torture_hrtimeout_s(), each of which uses hrtimers to block for a fuzzed
time interval.  These functions are intended to be used by the various
torture tests to decouple wakeups from the timer wheel, thus providing
more opportunity for Murphy to insert destructive race conditions.

Signed-off-by: Paul E. McKenney

rcutorture: Add races with task-exit processing

2020-06-29T19:01:44+00:00

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

locktorture.c: Fix if-statement empty body warnings

2020-04-27T18:05:13+00:00

When using -Wextra, gcc complains about torture_preempt_schedule()
when its definition is empty (i.e., when CONFIG_PREEMPTION is not
set/enabled).  Fix these warnings by adding an empty do-while block
for that macro when CONFIG_PREEMPTION is not set.
Fixes these build warnings:

../kernel/locking/locktorture.c:119:29: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../kernel/locking/locktorture.c:166:29: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../kernel/locking/locktorture.c:337:29: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../kernel/locking/locktorture.c:490:29: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../kernel/locking/locktorture.c:528:29: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../kernel/locking/locktorture.c:553:29: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]

I have verified that there is no object code change (with gcc 7.5.0).

Signed-off-by: Randy Dunlap 
Cc: Davidlohr Bueso 
Cc: Josh Triplett 
Signed-off-by: "Paul E. McKenney"

rcu: Use CONFIG_PREEMPTION

2019-07-31T17:03:35+00:00

CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by
CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same
functionality which today depends on CONFIG_PREEMPT.

Switch the conditionals in RCU to use CONFIG_PREEMPTION.

That's the first step towards RCU on RT. The further tweaks are work in
progress. This neither touches the selftest bits which need a closer look
by Paul.

Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Masami Hiramatsu 
Cc: Paolo Bonzini 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Link: http://lkml.kernel.org/r/20190726212124.210156346@linutronix.de
Signed-off-by: Ingo Molnar

torture: Allow inter-stutter interval to be specified

2019-05-28T16:06:09+00:00

Currently, the inter-stutter interval is the same as the stutter duration,
that is, whatever number of jiffies is passed into torture_stutter_init().
This has worked well for quite some time, but the addition of
forward-progress testing to rcutorture can delay processes for several
seconds, which can triple the time that they are stuttered.

This commit therefore adds a second argument to torture_stutter_init()
that specifies the inter-stutter interval.  While locktorture preserves
the current behavior, rcutorture uses the RCU CPU stall warning interval
to provide a wider inter-stutter interval.

Signed-off-by: Paul E. McKenney