Hi GIlles,
As you suggested, I have prepared simple test case that demonstrate how Xenomai
is utilized by OROCOS. This test case behaves exactly the same like helloword
example. Scheduler is chosen before any mutex are processed, so in my opinion
it is not the case which you defined. What is really surprising is that the
replacing TM_NONBLOCK with TM_INFINITE, in one before last line, do magic and
suppress signal generation. Furthermore, there is no call to
'rt_task_set_mode(0, T_WARNSW, NULL);' so why
signal is generated? If we enable T_WARNSW in the thread, SIGXCPU is generated
when mutex is locked first time in the thread.
Code is following:
/*****************************************************************************
* mutexTest.c
* Xenomai mutex test for SIGXCPU
* Mariusz Janiak
* Wroclaw 2013
*****************************************************************************/
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <execinfo.h>
#include <sched.h>
#include <native/task.h>
#include <native/mutex.h>
#include <native/sem.h>
#define ORO_SCHED_OTHER 1 /** Soft real-time */
#ifdef UNUSED
#elif defined(__GNUC__)
# define UNUSED(x) UNUSED_ ## x __attribute__((unused))
#else
# define UNUSED(x) x
#endif
void test(void *UNUSED(arg));
void warn_upon_switch(int UNUSED(sig));
RT_TASK mainTask, testTask;
RT_MUTEX mutex;
RT_SEM sem;
void warn_upon_switch(int UNUSED(sig))
{
void *bt[32];
int nentries;
nentries = backtrace(bt, sizeof(bt) / sizeof(bt[0]));
backtrace_symbols_fd(bt, nentries, fileno(stderr));
}
void test(void *UNUSED(arg))
{
/* thread_function() in Thread.cpp:83 -- Thread::configure() in
Thread.cpp:489 -- rtos_task_set_period(...) in fosi_internal.cpp:387 --
rtos_task_make_periodic(...) in fosi_internal.cpp:378*/
rt_task_set_periodic(NULL, TM_NOW, TM_INFINITE);
/* thread_function() in Thread.cpp:86 -- rtos_sem_signal(...) in fosi.h:188*/
rt_sem_v(&sem);
/* thread_function() in Thread.cpp:89 -- MutexLock */
rt_mutex_acquire(&mutex, TM_INFINITE);
rt_mutex_release(&mutex);
/* hread_function() in Thread.cpp:116 -- rtos_sem_wait(...) in fosi.h:194 */
rt_sem_p(&sem, TM_INFINITE);
}
int main(int UNUSED(argc), char *UNUSED(argv[]))
{
int ret=0;
struct sched_param param;
struct sigaction sa;
/* rtos_task_create_main(...) in fosi_internal.cpp:82 */
mlockall(MCL_CURRENT|MCL_FUTURE);
/* rtos_task_create_main(...) in fosi_internal.cpp:91 */
param.sched_priority = sched_get_priority_max(ORO_SCHED_OTHER);
if (param.sched_priority != -1 ){
sched_setscheduler(0, ORO_SCHED_OTHER, ¶m);
}
/* rtos_task_create_main(...) in fosi_internal.cpp:102 */
ret = rt_task_shadow(&mainTask, "MutexTest", 0, 0);
if(ret < 0){
printf("ERROR: rt_task_shadow(...)\n");
return -1;
}
/* rtos_task_create_main(...) in fosi_internal.cpp:162 */
sa.sa_sigaction = warn_upon_switch;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
sigaction(SIGXCPU, &sa, 0);
/* Thread::Thread(...) in Thread.cpp:238 -- automatic in constructor */
rt_mutex_create(&mutex, "breaker");
/* Thread::setup(...) in Thread.cpp:257 -- in MutexLock constructor */
ret = rt_mutex_acquire(&mutex, TM_INFINITE);
/* Thread::setup(...) in Thread.cpp:264 -- rtos_sem_init(...) in fosi.h:176*/
rt_sem_create(&sem, "sem", 0, S_PRIO);
/* Thread::setup(...) in Thread.cpp:293 -- rtos_task_create(...) in
fosi_internal.cpp:240 */
ret = rt_task_spawn(&testTask, "testTask", 128000, 1, T_JOINABLE | (0 &
T_CPUMASK), test, NULL);
if(ret < 0){
printf("ERROR: rt_task_spawn(...)\n");
return -1;
}
/* Thread::setup(...) in Thread.cpp:309 -- rtos_sem_wait(...) in fosi.h:194 */
rt_sem_p(&sem, TM_INFINITE);
/* Thread::setup(...) in Thread.cpp:324 -- in MutexLock destructor */
rt_mutex_release(&mutex);
/* Do something */
sleep(1);
/* Thread::terminate() in Thread.cpp:614 -- rtos_sem_signal(...) in
fosi.h:188*/
rt_sem_v(&sem);
/* Thread::terminate() in Thread.cpp:616 -- rtos_task_delete(...) in
fosi_internal.cpp:490*/
rt_task_join(&testTask);
rt_task_delete(&testTask);
/* Thread::~Thread() in Thread.cpp:326 -- automatic in destructor when
TaskContext::setActivity(...) is called by HelloWord object (default
activity created in object constructor is replaced by new activity)*/
rt_mutex_acquire(&mutex, TM_NONBLOCK); /* rtos_mutex_trylock(...) in
fosi.h:247 */
rt_mutex_release(&mutex); /* we get the SIG here!!! */
return 0;
}
Building procedure (you need Obj, Dep and Bin dirs in the current path, and
Xenomai in /usr/xenomai)
gcc -c -Wp,-MM,-MP,-MT,mutexTest.o,-MF,Dep/mutexTest.d -O2 -ggdb3 -DDEBUG_EN
-I/usr/xenomai/include -D_GNU_SOURCE -D_REENTRANT -D__XENO__ -Wall -Wextra
-Wcast-align -Wimplicit -Wpointer-arith -Wswitch -Wredundant-decls
-Wreturn-type -Wunused -Wsign-compare -Waggregate-return -Wnested-externs
-Wmissing-prototypes -Wstrict-prototypes -Wmissing-declarations
-Wbad-function-cast mutexTest.c -o Obj/mutexTest.o
gcc -o Bin/mutexTest.run Obj/mutexTest.o -lnative -L/usr/xenomai/lib -lxenomai
-lpthread -lrt -lm
Mariusz
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