Re: [PATCH V4 03/20] rv/include: Add helper functions for deterministic automata

[Daniel Bristot de Oliveira <bristot@kernel.org>]

On 7/6/22 20:35, Tao Zhou wrote:
> On Thu, Jun 16, 2022 at 10:44:45AM +0200, Daniel Bristot de Oliveira wrote:
> 
>> Formally, a deterministic automaton, denoted by G, is defined as a
>> quintuple:
>>
>>   G = { X, E, f, x_0, X_m }
>>
>> where:
>> 	- X is the set of states;
>> 	- E is the finite set of events;
>> 	- x_0 is the initial state;
>> 	- X_m (subset of X) is the set of marked states.
>> 	- f : X x E -> X $ is the transition function. It defines the
>> 	  state transition in the occurrence of a event from E in
>> 	  the state X. In the special case of deterministic automata,
>> 	  the occurrence of the event in E in a state in X has a
>> 	  deterministic next state from X.
>>
>> An automaton can also be represented using a graphical format of
>> vertices (nodes) and edges. The open-source tool Graphviz can produce
>> this graphic format using the (textual) DOT language as the source code.
>>
>> The dot2c tool presented in this paper:
>>
>> DE OLIVEIRA, Daniel Bristot; CUCINOTTA, Tommaso; DE OLIVEIRA, Romulo
>> Silva. Efficient formal verification for the Linux kernel. In:
>> International Conference on Software Engineering and Formal Methods.
>> Springer, Cham, 2019. p. 315-332.
>>
>> Translates a deterministic automaton in the DOT format into a C
>> surce code representation that to be used for monitoring.
>>
>> This header file implements helper functions to facilitate the usage
>> of the C output from dot2c for monitoring.
>>
>> Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
>> Cc: Guenter Roeck <linux@roeck-us.net>
>> Cc: Jonathan Corbet <corbet@lwn.net>
>> Cc: Steven Rostedt <rostedt@goodmis.org>
>> 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: 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>
>> ---
>>  include/rv/automata.h | 49 +++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 49 insertions(+)
>>  create mode 100644 include/rv/automata.h
>>
>> diff --git a/include/rv/automata.h b/include/rv/automata.h
>> new file mode 100644
>> index 000000000000..0c0aa54bd820
>> --- /dev/null
>> +++ b/include/rv/automata.h
>> @@ -0,0 +1,49 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Deterministic automata helper functions, to be used with the automata
>> + * models in C generated by the dot2k tool.
>> + *
>> + * Copyright (C) 2019-2022 Daniel Bristot de Oliveira <bristot@kernel.org>
>> + */
>> +
>> +#define DECLARE_AUTOMATA_HELPERS(name, type)					\
>> +										\
>> +static inline void *model_get_model_##name(void)				\
>> +{										\
>> +	return (void *) &automaton_##name;					\
>> +}									\
>> +										\
>> +static char *model_get_state_name_##name(enum states_##name state)		\
>> +{										\
>> +	return automaton_##name.state_names[state];				\
>> +}										\
>> +										\
>> +static char *model_get_event_name_##name(enum events_##name event)		\
>> +{										\
>> +	return automaton_##name.event_names[event];				\
>> +}										\
>> +										\
>> +static inline type model_get_init_state_##name(void)				\
>> +{										\
>> +	return automaton_##name.initial_state;					\
>> +}										\
>> +										\
>> +static inline type model_get_next_state_##name(enum states_##name curr_state,	\
>> +					       enum events_##name event)	\
>> +{										\
>> +	if ((curr_state < 0) || (curr_state > state_max_##name))		\
>> +		return -1;							\
> 
> curr_state can not be state_max_xxx. curr_state must be not bigger
> than state_max_xxx. Or am I miss something?
> 
>> +	if ((event < 0) || (event > event_max_##name))				\
>> +		return -1;							\
>> +										\
> 
> Same here for the event boundary check.
> 
>> +	return automaton_##name.function[curr_state][event];			\
>> +}										\
>> +										\
>> +static inline bool model_is_final_state_##name(enum states_##name state)	\
>> +{										\
>> +	if ((state < 0) || (state > state_max_##name))				\
>> +		return 0;							\
>> +										\
> 
> Same here.
> 
>> +	return !!automaton_##name.final_states[state];				\
> 
> If the value of .final_states[state] is 0 or 1, can the type of
> .final_states[state] be befined to bool. Or not need to use !! to
> explicitly transfer the type to bool. I remember that you define
> this as char array and the matrix model value of this array is 0 or 1
> see from the next patche. 1 delegate the state it is the initial state.
> 0 for others.

All points addressed!
-- Daniel