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rv_react() is exported to modules, but the reactor registration helpers
are not. Export them with EXPORT_SYMBOL_GPL() so reactor modules and
the tristate KUnit test module can register and unregister reactors
without hitting undefined symbol errors at link time(modpost).
Commit 3d3800b4f7f4 ("rv: Remove reactor's reference counter") noted
that module-based reactors, if supported, should be pinned with
try_module_get()/module_put() to prevent unloading under an active
monitor. This patch does not add that support. The only in-tree module
consumer, the tristate KUnit reactor test module, registers and
unregisters its reactor within a controlled test lifecycle.
The actual pinning is left to a follow-up series that adds support for
loadable-module reactors.
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Wen Yang <wen.yang@linux.dev>
Link: https://lore.kernel.org/r/94b7ec120a92b9368541ac050601e66be8fe653a.1789412799.git.wen.yang@linux.dev
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
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rv_react() overrides the lockdep wait type to LD_WAIT_FREE to enforce
that reactor callbacks take no locks. But callbacks run in the context
of the triggering tracepoint, which can be preemptible task context on
any kernel. A timer interrupt firing during the callback makes the
interrupt-exit path schedule and take rq->__lock (LD_WAIT_SPIN) while
the LD_WAIT_FREE override is still held, producing a spurious
"Invalid wait context" warning:
[ BUG: Invalid wait context ]
context-{5:5}
1 lock held by kunit_try_catch/209:
#0: (rv_react_map-wait-type-override){+.+.}-{1:1}
kunit_try_catch/209 is trying to lock:
ffff8a743ed3e8a0 (&rq->__lock){-...}-{2:2}
Use LD_WAIT_SPIN instead of LD_WAIT_FREE, which causes false-positive
warnings in preemptible contexts due to scheduler preemption taking
rq->__lock.
Fixes: 69d8895cb9a9 ("rv: Add explicit lockdep context for reactors")
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Wen Yang <wen.yang@linux.dev>
Cc: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://lore.kernel.org/r/5586dd00789a0f904cc299cd8889744b8c6f8dc9.1789412799.git.wen.yang@linux.dev
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
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Export rv_get_task_monitor_slot, rv_put_task_monitor_slot, and rv_react
to GPL modules so they can be accessed by KUnit and future monitors
built as kernel modules.
Reviewed-by: Nam Cao <namcao@linutronix.de>
Link: https://lore.kernel.org/r/20260723074534.43521-12-gmonaco@redhat.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
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Convert to use __free to tidy up the code.
Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/r/62854e2fcb8f8dd2180a98a9700702dcf89a6980.1763370183.git.namcao@linutronix.de
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
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Convert to use lock guard to tidy up the code.
Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/r/dbefeb868093c40d4b29fd6b57294a6aa011b719.1763370183.git.namcao@linutronix.de
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
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Reactors can be called from any context through tracepoints.
When developing reactors care needs to be taken to only call APIs which
are safe. As the tracepoints used during testing may not actually be
called from restrictive contexts lockdep may not be helpful.
Add explicit overrides to help lockdep find invalid code patterns.
The usage of LD_WAIT_FREE will trigger lockdep warnings in the panic
reactor. These are indeed valid warnings but they are out of scope for
RV and will instead be fixed by the printk subsystem.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Acked-by: Nam Cao <namcao@linutronix.de>
Link: https://lore.kernel.org/r/20251014-rv-lockdep-v1-3-0b9e51919ea8@linutronix.de
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
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There are no external users left.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://lore.kernel.org/r/20251014-rv-lockdep-v1-2-0b9e51919ea8@linutronix.de
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
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The only thing the reactors can do with the passed in varargs is to
convert it into a va_list. Do that in a central helper instead.
It simplifies the reactors, removes some hairy macro-generated code
and introduces a convenient hook point to modify reactor behavior.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://lore.kernel.org/r/20251014-rv-lockdep-v1-1-0b9e51919ea8@linutronix.de
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
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Argument 'p' of reactors_show() and monitor_reactor_show() is not a pointer
to struct rv_reactor, it is actually a pointer to the list_head inside
struct rv_reactor. Therefore it's wrong to cast 'p' to struct rv_reactor *.
This wrong type cast has been there since the beginning. But it still
worked because the list_head was the first field in struct rv_reactor_def.
This is no longer true since commit 3d3c376118b5 ("rv: Merge struct
rv_reactor_def into struct rv_reactor") moved the list_head, and this wrong
type cast became a functional problem.
Properly use container_of() instead.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/b4febbd6844311209e4c8768b65d508b81bd8c9b.1753625621.git.namcao@linutronix.de
Fixes: 3d3c376118b5 ("rv: Merge struct rv_reactor_def into struct rv_reactor")
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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The field 'reacting' in struct rv_monitor is set but never used. Delete it.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/a6c16f845d2f1a09c4d0934ab83f3cb14478a71d.1753378331.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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rv_reactor has a reference counter to ensure it is not removed while
monitors are still using it.
However, this is futile, as __exit functions are not expected to fail and
will proceed normally despite rv_unregister_reactor() returning an error.
At the moment, reactors do not support being built as modules, therefore
they are never removed and the reference counters are not necessary.
If we support building RV reactors as modules in the future, kernel
module's centralized facilities such as try_module_get(), module_put() or
MODULE_SOFTDEP should be used instead of this custom implementation.
Remove this reference counter.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/bb946398436a5e17fb0f5b842ef3313c02291852.1753378331.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Each struct rv_reactor has a unique struct rv_reactor_def associated with
it. struct rv_reactor is statically allocated, while struct rv_reactor_def
is dynamically allocated.
This makes the code more complicated than it should be:
- Lookup is required to get the associated rv_reactor_def from rv_reactor
- Dynamic memory allocation is required for rv_reactor_def. This is
harder to get right compared to static memory. For instance, there is
an existing mistake: rv_unregister_reactor() does not free the memory
allocated by rv_register_reactor(). This is fortunately not a real
memory leak problem as rv_unregister_reactor() is never called.
Simplify and merge rv_reactor_def into rv_reactor.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/71cb91c86cd40df5b8c492b788787f2a73c3eaa3.1753378331.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Each struct rv_monitor has a unique struct rv_monitor_def associated with
it. struct rv_monitor is statically allocated, while struct rv_monitor_def
is dynamically allocated.
This makes the code more complicated than it should be:
- Lookup is required to get the associated rv_monitor_def from rv_monitor
- Dynamic memory allocation is required for rv_monitor_def. This is
harder to get right compared to static memory. For instance, there is
an existing mistake: rv_unregister_monitor() does not free the memory
allocated by rv_register_monitor(). This is fortunately not a real
memory leak problem, as rv_unregister_monitor() is never called.
Simplify and merge rv_monitor_def into rv_monitor.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/194449c00f87945c207aab4c96920c75796a4f53.1753378331.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Each RV monitor has one static buffer to send to the reactors. If multiple
errors are detected simultaneously, the one buffer could be overwritten.
Instead, leave it to the reactors to handle buffering.
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Monitors describing complex systems, such as the scheduler, can easily
grow to the point where they are just hard to understand because of the
many possible state transitions.
Often it is possible to break such descriptions into smaller monitors,
sharing some or all events. Enabling those smaller monitors concurrently
is, in fact, testing the system as if we had one single larger monitor.
Splitting models into multiple specification is not only easier to
understand, but gives some more clues when we see errors.
Add the possibility to create container monitors, whose only purpose is
to host other nested monitors. Enabling a container monitor enables all
nested ones, but it's still possible to enable nested monitors
independently.
Add the sched monitor as first container, for now empty.
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/20250305140406.350227-3-gmonaco@redhat.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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no_llseek had been defined to NULL two years ago, in commit 868941b14441
("fs: remove no_llseek")
To quote that commit,
At -rc1 we'll need do a mechanical removal of no_llseek -
git grep -l -w no_llseek | grep -v porting.rst | while read i; do
sed -i '/\<no_llseek\>/d' $i
done
would do it.
Unfortunately, that hadn't been done. Linus, could you do that now, so
that we could finally put that thing to rest? All instances are of the
form
.llseek = no_llseek,
so it's obviously safe.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Unlock the "rv_interface_lock" mutex before returning.
Link: https://lkml.kernel.org/r/YuvYzNfGMgV+PIhd@kili
Fixes: 04acadcb4453 ("rv: Add runtime reactors interface")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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A runtime monitor can cause a reaction to the detection of an
exception on the model's execution. By default, the monitors have
tracing reactions, printing the monitor output via tracepoints.
But other reactions can be added (on-demand) via this interface.
The user interface resembles the kernel tracing interface and
presents these files:
"available_reactors"
- Reading shows the available reactors, one per line.
For example:
# cat available_reactors
nop
panic
printk
"reacting_on"
- It is an on/off general switch for reactors, disabling
all reactions.
"monitors/MONITOR/reactors"
- List available reactors, with the select reaction for the given
MONITOR inside []. The default one is the nop (no operation)
reactor.
- Writing the name of a reactor enables it to the given
MONITOR.
For example:
# cat monitors/wip/reactors
[nop]
panic
printk
# echo panic > monitors/wip/reactors
# cat monitors/wip/reactors
nop
[panic]
printk
Link: https://lkml.kernel.org/r/1794eb994637457bdeaa6bad0b8263d2f7eece0c.1659052063.git.bristot@kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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