Hi,
I'm experiencing an strange segmentation fault problem. I've boiled down
the code to the simplest possible program that causes the segfault:
1- Set the timer in oneshot mode.
2- Create a task.
3- Start the task.
At the task function:
1- Make the task periodic (1s).
2- Issue a fprintf.
That's all. The code segfaults. If I remove the fprintf, it won't
segfault. If I change it for a printf, it won't segfault.
If I use fprintf but print just "TICK" instead of "TICK %u", it won't
segfault while the task is running, but it will when the program is
interrupted (not shown here, but I tried this with a signal handler in
place that properly deleted the task, though I think this is not
absolutely necessary).
I'm totally confused.
I know I can use fprintf as long as I assume that the RT task will go
into "secondary" mode at this point because it'll be using linux
services, and that it will go back to "primary" RT mode on the next call
to rt_task_wait_period.
Also, I know that it would be best to use periodic instead of oneshot
mode, but my program is obviously more complex than this boiled down
example and really needs oneshot mode.
Any ideas about what could be the problem?
Thanks.
P.S: This is the same problem I described earlier inthe list as caused
by inb. I though that inb was the cause because removing it avoided the
segfault, however, it turns out that removing the inb was causing
another piece of code containing the fprintf not to execute.
//===========================================================================
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/io.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <native/task.h>
#include "main.h"
static RT_TASK _io_task;
static void _io_proc (void *arg) {
u_long overrun;
rt_task_set_periodic(&_io_task, TM_NOW,
rt_timer_ns2ticks(1000000000LL));
for (;;) {
rt_task_wait_period(&overrun);
fprintf(stderr, "TICK %u\n", 1);
}
}
static void _cleanup (void) {
rt_task_delete(&_io_task);
}
static int _init (void) {
int r;
r = rt_timer_set_mode(TM_ONESHOT);
if (r < 0) {
fprintf(stderr, "ERROR %i initializing RT\n", r);
_cleanup(); return r;
}
r = rt_task_create(&_io_task, "rtcore_io_task", 0x1000, 10, T_FPU);
if (r < 0) {
fprintf(stderr, "ERROR %i creating task\n", r);
_cleanup(); return r;
}
r = rt_task_start(&_io_task, &_io_proc, NULL);
if (r < 0) {
fprintf(stderr, "ERROR %i starting task\n", r);
_cleanup(); return r;
}
return 0;
}
int main (int argc, char **argv) {
iopl(3);
mlockall(MCL_CURRENT | MCL_FUTURE);
if ( _init() < 0) return 1;
for (;;) sleep(1);
_cleanup();
return 0;
}
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