Because SRCU-lite is being replaced by SRCU-fast, this commit removes
support for SRCU-lite from rcutorture.c
Both SRCU-lite and SRCU-fast provide faster readers by dropping the
smp_mb() call from their lock and unlock primitives, but incur a pair
of added RCU grace periods during the SRCU grace period. There is a
trivial mapping from the SRCU-lite API to that of SRCU-fast, so there
should be no transition issues.
[ paulmck: Apply Christoph Hellwig feedback. ]
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Trivial RCU is a textbook implementation that is not used in the
Linux kernel, but tested to keep textbooks (and presentations) honest.
It is so trivial that it cannot deal with either CPU hotplug or external
migration from one CPU to another. This commit therefore splats whenever
onoff_interval or shuffle_interval are non-zero, and then sets them to
zero in order to avoid false-positive failures.
Those wishing to set these module parameters in order to force failures
in Trivial RCU are free to revert this commit. Just don't expect me to
be sympathetic to any resulting bug reports!
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202505131651.af6e81d7-lkp@intel.com
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Given that the rcutorture_one_extend_check() function now uses
in_serving_softirq() and in_hardirq(), it is no longer necessary to pass
insoftirq flags down the function-call stack. This commit therefore
removes those flags, and, while in the area, does a bit of whitespace
cleanup.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
This commit prints the number of RCU up/down readers and the number
of such readers that migrated from one CPU to another, along
with the rest of the periodic rcu_torture_stats_print() output.
These statistics are currently used only by srcu_down_read{,_fast}()
and srcu_up_read(,_fast)().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
The design of testing of up/down readers such as srcu_down_read()
and srcu_up_read() assumes that these are tested only by the
rcu_torture_updown() kthread, and never by the rcu_torture_reader()
kthread. Because we all know which road is paved with good intentions,
this commit adds WARN_ON_ONCE() to verify that things are going to plan.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
This commit creates counters in the rcu_torture_one_read_state_updown
structure that check for a call to ->up_read() that lacks a matching
call to ->down_read().
While in the area, add end-of-run cleanup code that prevents calls to
rcu_torture_updown_hrt() from happening after the test has moved on. Yes,
the srcu_barrier() at the end of the test will wait for them, but this
could result in confusing states, statistics, and diagnostic information.
So explicitly wait for them before we get to the end-of-test output.
[ paulmck: Apply kernel test robot feedback. ]
[ joel: Apply Boqun's fix for counter increment ordering. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
The down/up SRCU reader testing uses an hrtimer handler to exit the SRCU
read-side critical section. This might be delayed, and if delayed for
too long, it can prevent the rcutorture run from completing. This commit
therefore complains if the hrtimer handler is delayed for more than
ten seconds.
[ paulmck, joel: Apply kernel test robot feedback to avoid
false-positive complaint of excessive ->up_read() delays by using
HRTIMER_MODE_HARD ]
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
This is strictly a code-movement commit, pulling that part of
the rcu_torture_updown() function's loop body that processes
one rcu_torture_one_read_state_updown structure into a new
rcu_torture_updown_one() function. The checks for the end of the
torture test and the current structure being in use remain in the
rcu_torture_updown() function.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
This commit adds a new rcutorture.n_up_down kernel boot parameter
that specifies the number of outstanding SRCU up/down readers, which
begin in kthread context and end in an hrtimer handler. There is a new
kthread ("rcu_torture_updown") that scans an per-reader array looking
for elements whose readers have ended. This kthread sleeps between one
and two milliseconds between consecutive scans.
[ paulmck: Apply kernel test robot feedback. ]
[ paulmck: Apply Z qiang feedback. ]
[ joel: Fix build error: hrtimer_init is replaced by hrtimer_setup. ]
[ joel: Apply Boqun bug fix to drop extra up_read() call in
rcu_torture_updown()].
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
This commit retrospectively prepares for testing of RCU readers invoked
from hardware interrupt handlers (for example, HRTIMER_MODE_HARD hrtimer
handlers) in kernels built with CONFIG_RCU_TORTURE_TEST_CHK_RDR_STATE=y,
which is rarely used but sometimes extremely useful. This preparation
involves taking early exits if in_hardirq(), and, while we are in the
area, a very early exit if in_nmi().
This means that a number of insoftirq parameters are no longer needed,
but that is the subject of a later commit.
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202505140917.8ee62cc6-lkp@intel.com
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Testing of rcutorture's SRCU-P scenario on a large arm64 system resulted
in rcu_torture_writer() forward-progress failures, but these same tests
passed on x86. After some off-list discussion of possible memory-ordering
causes for these failures, Boqun showed that these were in fact due to
reordering, but by the scheduler, not by the memory system. On x86,
rcu_torture_writer() would have run quickly enough that by the time
the rcu_torture_updown() kthread started, the rcu_torture_current
variable would already be initialized, thus avoiding a bug in which
a NULL value would cause rcu_torture_updown() to do an extra call to
srcu_up_read_fast().
This commit therefore moves creation of the rcu_torture_writer() kthread
after that of the rcu_torture_reader() kthreads. This results in
deterministic failures on x86.
What about the double-srcu_up_read_fast() bug? Boqun has the fix.
But let's also fix the test while we are at it!
Reported-by: Joel Fernandes <joelagnelf@nvidia.com>
Reported-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
The rcu_torture_writer() function scans the memory blocks after a stutter
(or forced idle) interval, complaining about any that have not passed
through ten grace periods since the start of the stutter interval.
But one splat suffices, so this commit therefore stops at the first splat.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
- Convert init_timer*(), try_to_del_timer_sync() and
destroy_timer_on_stack() over to the canonical timer_*() namespace
convention.
There are is another large converstion pending, which has not been included
because it would have caused a gazillion of merge conflicts in next. The
conversion scripts will be run towards the end of the merge window and a
pull request sent once all conflict dependencies have been merged.
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Merge tag 'timers-cleanups-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer cleanups from Thomas Gleixner:
"Another set of timer API cleanups:
- Convert init_timer*(), try_to_del_timer_sync() and
destroy_timer_on_stack() over to the canonical timer_*()
namespace convention.
There is another large conversion pending, which has not been included
because it would have caused a gazillion of merge conflicts in next.
The conversion scripts will be run towards the end of the merge window
and a pull request sent once all conflict dependencies have been
merged"
* tag 'timers-cleanups-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
treewide, timers: Rename destroy_timer_on_stack() as timer_destroy_on_stack()
treewide, timers: Rename try_to_del_timer_sync() as timer_delete_sync_try()
timers: Rename init_timers() as timers_init()
timers: Rename NEXT_TIMER_MAX_DELTA as TIMER_NEXT_MAX_DELTA
timers: Rename __init_timer_on_stack() as __timer_init_on_stack()
timers: Rename __init_timer() as __timer_init()
timers: Rename init_timer_on_stack_key() as timer_init_key_on_stack()
timers: Rename init_timer_key() as timer_init_key()
Currently, the ->gpwrap is not tested (at all per my testing) due to the
requirement of a large delta between a CPU's rdp->gp_seq and its node's
rnp->gpseq.
This results in no testing of ->gpwrap being set. This patch by default
adds 5 minutes of testing with ->gpwrap forced by lowering the delta
between rdp->gp_seq and rnp->gp_seq to just 8 GPs. All of this is
configurable, including the active time for the setting and a full
testing cycle.
By default, the first 25 minutes of a test will have the _default_
behavior there is right now (ULONG_MAX / 4) delta. Then for 5 minutes,
we switch to a smaller delta causing 1-2 wraps in 5 minutes. I believe
this is reasonable since we at least add a little bit of testing for
usecases where ->gpwrap is set.
[ Apply fix for Dan Carpenter's bug report on init path cleanup. ]
[ Apply kernel doc warning fix from Akira Yokosawa. ]
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
The rcu_torture_reader() and rcu_torture_fwd_prog_cr() functions
run CPU-bound for extended periods of time (tens or even
hundreds of milliseconds), so they invoke tick_dep_set_task() and
tick_dep_clear_task() to ensure that the scheduling-clock tick helps
move grace periods forward.
So why doesn't rcu_torture_fwd_prog_nr() also invoke tick_dep_set_task()
and tick_dep_clear_task()? Because the point of this function is to test
RCU's ability to (eventually) force grace periods forward even when the
tick has been disabled during long CPU-bound kernel execution.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
The rcu_torture_one_read() function is designed for RCU readers that are
confined to a task, such that a single thread of control extends from the
beginning of a given RCU read-side critical section to its end. This does
not suffice for things like srcu_down_read() and srcu_up_read(), where
the critical section might start at task level and end in a timer handler.
This commit therefore creates separate init_rcu_torture_one_read_state(),
rcu_torture_one_read_start(), and rcu_torture_one_read_end() functions,
along with a rcu_torture_one_read_state structure to coordinate their
actions. These will be used to create tests for srcu_down_read()
and friends.
One caution: The caller to rcu_torture_one_read_start() must enter the
initial read-side critical section prior to the call. This enables use
of non-standard primitives such as srcu_down_read() while still using
the same validation code.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree
over and remove the historical wrapper inlines.
Conversion was done with coccinelle plus manual fixups where necessary.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The rcutorture_one_extend_check() function's second last check assumes
that "preempt_count() & PREEMPT_MASK" is non-zero only if
RCUTORTURE_RDR_PREEMPT or RCUTORTURE_RDR_SCHED bit is set.
This works for preemptible RCU and for non-preemptible RCU running in
a non-preemptible kernel. But it fails for non-preemptible RCU running
in a preemptible kernel because then rcu_read_lock() is just
preempt_disable(), which increases preempt count.
This commit therefore adjusts this check to take into account the case
fo non-preemptible RCU running in a preemptible kernel.
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
The rcutorture_one_extend_check() function's last check assumes that
if cur_ops->readlock_nesting() returns greater than zero, either the
RCUTORTURE_RDR_RCU_1 or the RCUTORTURE_RDR_RCU_2 bit must be set, that
is, there must be at least one rcu_read_lock() in effect.
This works for preemptible RCU and for non-preemptible RCU running in
a non-preemptible kernel. But it fails for non-preemptible RCU running
in a preemptible kernel because then RCU's cur_ops->readlock_nesting()
function, which is rcu_torture_readlock_nesting(), will return
the PREEMPT_MASK mask bits from preempt_count(). The result will
be greater than zero if preemption is disabled, including by the
RCUTORTURE_RDR_PREEMPT and RCUTORTURE_RDR_SCHED bits.
This commit therefore adjusts this check to take into account the case
fo non-preemptible RCU running in a preemptible kernel.
[boqun: Fix the if condition and add comment]
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202502171415.8ec87c87-lkp@intel.com
Co-developed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Co-developed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Currently "nfakewriters" parameter can be set to any value but
there is no possibility to adjust it automatically based on how
many CPUs a system has where a test is run on.
To address this, if the "nfakewriters" is set to negative it will
be adjusted to num_online_cpus() during torture initialization.
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Link: https://lore.kernel.org/r/20250227131613.52683-1-urezki@gmail.com
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Currently, rcutorture ignores reader_flavor bits that are not in the
SRCU_READ_FLAVOR_ALL bitmask, which could confuse rcutorture users into
believing buggy patches had been fully tested. This commit therefore
produces a splat in this case.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
The Tree and Tiny implementations of rcutorture_format_gp_seqs() use
hard-coded constants for the length of the buffer that they format into.
This is of course an accident waiting to happen, so this commit therefore
makes them take a length argument. The rcutorture calling code uses
ARRAY_SIZE() to safely compute this new argument.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
This commit adds an ftrace-compatible microsecond-scale timestamp
to the failure/close-call output, but only in kernels built with
CONFIG_RCU_TORTURE_TEST_LOG_GP=y.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
With only eight bits per grace-period sequence number, wrap can happen
in 64 grace periods. This commit therefore increases this to sixteen
bits for normal grace-period sequence numbers and the combined short-form
polling sequence numbers, thus deferring wrap for at least 16,384 grace
periods. Because expedited grace periods go faster, expand these to 24
bits, deferring wrap for at least 4,194,304 expedited grace periods.
These longer wrap times makes it easier to correlate these numbers to
trace-event output.
Note that the low-order two bits are reserved for intra-grace-period
state, hence the above wrap numbers being a factor of four smaller than
you might expect.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
This commit includes the grace-period sequence numbers at the beginning
and end of each segment in the "Failure/close-call rcutorture reader
segments" list. These are in hexadecimal, and only the bottom byte.
Currently, only RCU is supported, with its three sequence numbers (normal,
expedited, and polled).
Note that if all the grace-period sequence numbers remain the same across
a given reader segment, only one copy of the number will be printed.
Of course, if there is a change, both sets of values will be printed.
Because the overhead of collecting this information can suppress
heisenbugs, this information is collected and printed only in kernels
built with CONFIG_RCU_TORTURE_TEST_LOG_GP=y.
[ paulmck: Apply Nathan Chancellor feedback for IS_ENABLED(). ]
[ paulmck: Apply feedback from kernel test robot. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
This commit adds a test_boost_holdoff module parameter that tells the RCU
priority-boosting tests to wait for the specified number of seconds past
the start of the rcutorture test. This can be useful when rcutorture
is built into the kernel (as opposed to being modprobed), especially on
large systems where early start of RCU priority boosting can delay the
boot sequence, which adds a full CPU's worth of load onto the system.
This can in turn result in pointless stall warnings.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
This commit permits rcutorture to test srcu_read_{,un}lock_fast(), which
is specified by the rcutorture.reader_flavor=0x8 kernel boot parameter.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: <bpf@vger.kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
This commit stops using ->srcu_idx for rcutorture's reader-batch
consistency checking, using ->srcu_gp_seq instead. This is a first
step towards a faster srcu_read_{,un}lock_lite() that avoids the array
accesses that use ->srcu_idx.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: <bpf@vger.kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
This commit converts rcutorture.c values for the reader_flavor module
parameter from hexadecimal to the SRCU_READ_FLAVOR_* C-preprocessor
macros. The actual modprobe or kernel-boot-parameter values for
read_flavor must still be entered in hexadecimal.
Link: https://lore.kernel.org/all/c48c9dca-fe07-4833-acaa-28c827e5a79e@amd.com/
Suggested-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
For preemptible RCU, this commit adds an indication for each
reader segments to whether the rcu_torture_reader() task was
on the ->blkd_tasks lists, though only in kernels built with
CONFIG_RCU_TORTURE_TEST_LOG_CPU=y.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Currently, rcutorture_one_extend() reads the CPU ID before making any
change to the type of RCU reader. This can be confusing because the
properties of the code from which the CPU ID is read are not that of
the reader segment that this same CPU ID is listed with.
This commit therefore causes rcutorture_one_extend() to read the CPU
ID just after the new protections have been added, but before the old
protections have been removed. With this change in place, all of the
protections of a given reader segment apply from the reading of one CPU ID
to the reading of the next. This change therefore also allows a single
read of the CPU ID to work for both the old and the new reader segment.
And this dual use of a single read of the CPU ID avoids inflicting any
additional to heisenbugs.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This commit adds the value of preempt_count() to the diagnostics produced
by rcutorture_one_extend_check() to improve debugging.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This commit adds rcutorture module parameters gp_cond_wi, gp_cond_wi_exp,
gp_poll_wi, and gp_poll_wi_exp to control the wait interval for
conditional, conditional expedited, polled, and polled expedited grace
periods, respectively. When rcu_torture_writer() is testing these types
of grace periods, hrtimers are used to randomly wait up to the specified
number of microseconds, but with nanosecond granularity.
In the case of conditional grace periods (get_state_synchronize_rcu()
and cond_synchronize_rcu(), for example) there is just one
wait. For polled grace periods (start_poll_synchronize_rcu() and
poll_state_synchronize_rcu(), for example), there is a repeated series
of waits until the grace period ends.
For normal grace periods, the default is 16 jiffies (for example, 16,000
microseconds on a HZ=1000 system) and for expedited grace periods the
default is 128 microseconds.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Use of the rcutorture preempt_duration and the default-on fwd_progress
kernel parameters can result in preemption of callback processing during
forward-progress testing, which is an excellent way to OOM your test
if your kernel offloads RCU callbacks. This commit therefore treats
preempt_duration in the same way as stall_cpu in CONFIG_RCU_NOCB_CPU=y
kernels, prohibiting fwd_progress testing and splatting when rcutorture
is built in (as opposed to being a loadable module).
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This commit adds reader-state debugging checks to a new function named
rcutorture_one_extend_check(), which is invoked before and after setting
new reader states by the existing rcutorture_one_extend() function.
These checks have proven to be rather heavyweight, reducing reproduction
rate of some failures by a factor of two. They are therefore hidden
behind a new RCU_TORTURE_TEST_CHK_RDR_STATE Kconfig option.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
The current "Failure/close-call rcutorture reader segments" output is
good and sufficient, but annoying when you have to interpret several
tens of them after an all-night rcutorture run. This commit therefore
makes them a bit more human-readable.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
The purpose of the "busted" torture type is to test rcutorture code paths
used only when a too-short grace period is detected. Currently, "busted"
only uses normal rcu_read_lock()-style readers, which fails to exercise
much of the "Failure/close-call rcutorture reader segments" functionality.
This commit therefore sets the .extendables field of rcu_busted_ops to
RCUTORTURE_MAX_EXTEND in order to more fully exercise the reporting.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
In kernels built with CONFIG_RCU_TORTURE_TEST_LOG_CPU=y, the CPU is
logged at the beginning of each reader segment. This commit further
logs it at the end of the full set of reader segments in order to show
any migration that might have occurred during the last reader segment.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This commit checks to see if the RCU reader has been preempted within
its read-side critical section for RCU flavors supporting this notion
(currently only preemptible RCU). If such a preemption occurred, then
this is printed at the end of the "Failure/close-call rcutorture reader
segments" list at the end of the rcutorture run.
[ paulmck: Apply kernel test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
The rcu_ops structure currently lacks a ->cond_sync_exp_full function,
which prevents testign of conditional full-state polled grace periods.
This commit therefore adds them, enabling testing this option.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
The rcu_torture_writer() polling currently uses timeouts ranging from
zero to 16 milliseconds to wait for the polled grace period to end.
This works, but it would be better to have a higher probability of
exercising races with the code that cleans up after a grace period.
This commit therefore switches from these millisecond-scale timeouts
to timeouts ranging from zero to 128 microseconds, and with a full
microsecond's worth of timeout fuzz.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This commit adds CPU number to the "Failure/close-call rcutorture reader
segments" list printed at the end of an rcutorture run that had too-short
grace periods. This information can help debugging interactions with
migration and CPU hotplug.
However, experience indicates that sampling the CPU number in rcutorture's
read-side code can reduce the probability of too-short bugs by a small
integer factor. And small integer factors are crucial to RCU bug hunting,
so this commit also introduces a default-off RCU_TORTURE_TEST_LOG_CPU
Kconfig option to enable this CPU-number-logging functionality at
build time.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This commit adds the rcutorture.preempt_duration kernel module parameter,
which gives the real-time preemption duration in milliseconds (zero to
disable, which is the default) and also the rcutorture.preempt_interval
module parameter, which gives the interval between successive preemptions,
also in milliseconds, defaulting to one second. The CPU to preempt is
chosen at random from those online at that time. Races between preempting
a given CPU and that CPU going offline are ignored, and preemption is
forgone when this occurs.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Current use cases of torture_sched_setaffinity() are well served by its
unconditional warning on error. However, an upcoming use case for a
preemption kthread needs to avoid warnings that might otherwise arise
when that kthread attempted to bind itself to a CPU on its way offline.
This commit therefore adds a dowarn argument that, when false, suppresses
the warning.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
- Tree wide:
* Make nr_irqs static to the core code and provide accessor functions
to remove existing and prevent future aliasing problems with local
variables or function arguments of the same name.
- Core code:
* Prevent freeing an interrupt in the devres code which is not managed
by devres in the first place.
* Use seq_put_decimal_ull_width() for decimal values output in
/proc/interrupts which increases performance significantly as it
avoids parsing the format strings over and over.
* Optimize raising the timer and hrtimer soft interrupts by using the
'set bit only' variants instead of the combined version which checks
whether ksoftirqd should be woken up. The latter is a pointless
exercise as both soft interrupts are raised in the context of the
timer interrupt and therefore never wake up ksoftirqd.
* Delegate timer/hrtimer soft interrupt processing to a dedicated thread
on RT.
Timer and hrtimer soft interrupts are always processed in ksoftirqd
on RT enabled kernels. This can lead to high latencies when other
soft interrupts are delegated to ksoftirqd as well.
The separate thread allows to run them seperately under a RT
scheduling policy to reduce the latency overhead.
- Drivers:
* New drivers or extensions of existing drivers to support Renesas
RZ/V2H(P), Aspeed AST27XX, T-HEAD C900 and ATMEL sam9x7 interrupt
chips
* Support for multi-cluster GICs on MIPS.
MIPS CPUs can come with multiple CPU clusters, where each CPU cluster
has its own GIC (Generic Interrupt Controller). This requires to
access the GIC of a remote cluster through a redirect register block.
This is encapsulated into a set of helper functions to keep the
complexity out of the actual code paths which handle the GIC details.
* Support for encrypted guests in the ARM GICV3 ITS driver
The ITS page needs to be shared with the hypervisor and therefore
must be decrypted.
* Small cleanups and fixes all over the place
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Merge tag 'irq-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull interrupt subsystem updates from Thomas Gleixner:
"Tree wide:
- Make nr_irqs static to the core code and provide accessor functions
to remove existing and prevent future aliasing problems with local
variables or function arguments of the same name.
Core code:
- Prevent freeing an interrupt in the devres code which is not
managed by devres in the first place.
- Use seq_put_decimal_ull_width() for decimal values output in
/proc/interrupts which increases performance significantly as it
avoids parsing the format strings over and over.
- Optimize raising the timer and hrtimer soft interrupts by using the
'set bit only' variants instead of the combined version which
checks whether ksoftirqd should be woken up. The latter is a
pointless exercise as both soft interrupts are raised in the
context of the timer interrupt and therefore never wake up
ksoftirqd.
- Delegate timer/hrtimer soft interrupt processing to a dedicated
thread on RT.
Timer and hrtimer soft interrupts are always processed in ksoftirqd
on RT enabled kernels. This can lead to high latencies when other
soft interrupts are delegated to ksoftirqd as well.
The separate thread allows to run them seperately under a RT
scheduling policy to reduce the latency overhead.
Drivers:
- New drivers or extensions of existing drivers to support Renesas
RZ/V2H(P), Aspeed AST27XX, T-HEAD C900 and ATMEL sam9x7 interrupt
chips
- Support for multi-cluster GICs on MIPS.
MIPS CPUs can come with multiple CPU clusters, where each CPU
cluster has its own GIC (Generic Interrupt Controller). This
requires to access the GIC of a remote cluster through a redirect
register block.
This is encapsulated into a set of helper functions to keep the
complexity out of the actual code paths which handle the GIC
details.
- Support for encrypted guests in the ARM GICV3 ITS driver
The ITS page needs to be shared with the hypervisor and therefore
must be decrypted.
- Small cleanups and fixes all over the place"
* tag 'irq-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
irqchip/riscv-aplic: Prevent crash when MSI domain is missing
genirq/proc: Use seq_put_decimal_ull_width() for decimal values
softirq: Use a dedicated thread for timer wakeups on PREEMPT_RT.
timers: Use __raise_softirq_irqoff() to raise the softirq.
hrtimer: Use __raise_softirq_irqoff() to raise the softirq
riscv: defconfig: Enable T-HEAD C900 ACLINT SSWI drivers
irqchip: Add T-HEAD C900 ACLINT SSWI driver
dt-bindings: interrupt-controller: Add T-HEAD C900 ACLINT SSWI device
irqchip/stm32mp-exti: Use of_property_present() for non-boolean properties
irqchip/mips-gic: Fix selection of GENERIC_IRQ_EFFECTIVE_AFF_MASK
irqchip/mips-gic: Prevent indirect access to clusters without CPU cores
irqchip/mips-gic: Multi-cluster support
irqchip/mips-gic: Setup defaults in each cluster
irqchip/mips-gic: Support multi-cluster in for_each_online_cpu_gic()
irqchip/mips-gic: Replace open coded online CPU iterations
genirq/irqdesc: Use str_enabled_disabled() helper in wakeup_show()
genirq/devres: Don't free interrupt which is not managed by devres
irqchip/gic-v3-its: Fix over allocation in itt_alloc_pool()
irqchip/aspeed-intc: Add AST27XX INTC support
dt-bindings: interrupt-controller: Add support for ASPEED AST27XX INTC
...
If a CPU runs throughout the stalled grace period without passing
through a quiescent state, RCU priority boosting cannot help.
The rcu_torture_boost_failed() function therefore prints a message
flagging the first such CPU. However, if the stall was instead due to
(for example) RCU's grace-period kthread being starved of CPU, there will
be no such CPU, causing rcu_check_boost_fail() to instead pass back -1
through its cpup CPU-pointer parameter.
Therefore, the current message complains about a mythical CPU -1.
This commit therefore checks for this situation, and notes that all CPUs
have passed through a quiescent state.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
