George,
timer_create(2) fails in the case where sigev_notify parameter of
sigevent structure is SIGEV_NONE. I believe this should not happen.
Consider following code which was run on x86:
#include <stdio.h>
#include <syscall.h>
#include <errno.h>
#include <time.h>
#include <signal.h>
#define ANYSIG SIGALRM /* Any signal value works*/
#ifndef __NR_timer_create
#if defined(__i386__)
#define __NR_timer_create 259
#elif defined(__ppc__)
#define __NR_timer_create 240
#elif defined(__powerpc64__)
#define __NR_timer_create 240
#elif defined(__x86_64__)
#define __NR_timer_create 222
#endif
#endif
_syscall3(int, timer_create, clockid_t, which_clock, struct sigevent *,
timer_event_spec, timer_t *, created_timer_id);
int main(int ac, char **av)
{
timer_t created_timer_id; /* holds the returned timer_id*/
struct sigevent evp;
int retval;
evp.sigev_value = (sigval_t) 0;
evp.sigev_signo = ANYSIG;
evp.sigev_notify = SIGEV_NONE;
retval = timer_create(CLOCK_REALTIME, &evp,
&created_timer_id);
if (retval < 0) {
perror("timer_crete");
printf("timer_create returned %d\n", retval);
} else {
printf("timer_create success");
}
return 0;
} /* End of main */
My analysis of this problem:
Kernel/include/asm-generic/siginfo.h contains following defintions
#define SIGEV_SIGNAL 0 /* notify via signal */
#define SIGEV_NONE 1 /* other notification: meaningless */
#define SIGEV_THREAD 2 /* deliver via thread creation */
#define SIGEV_THREAD_ID 4 /* deliver to thread */
In 2.5.68/kernel/posix-timers.c
Line 86:
MIPS_SEGV = ~(SIGEV_NONE & \
SIGEV_SIGNAL & \
SIGEV_THREAD & \
SIGEV_THREAD_ID)
= (001 & 000 & 010 & 100) = ~(000) = 111
Line 364: in good_sigevent()
Lets assume that event->sigev_notify = SIGEV_NONE = 001
Line 368:
SIGEV_NONE & SIGEV_THREAD_ID = 001 & 100 = 000. Therefore the if
statement becomes false
Line 373:
SIGEV_NONE & SIGEV_SIGNAL = 001 & 000 = 000. Therefore the if statement
is false
Line 377:
SIGEV_NONE & ~(SIGEV_SIGNAL | SIGEV_THREAD_ID)
= 001 & ~(000 | 100)
= 001 & ~(100)
= 001 & 011
= 001
therefore the if condition is true
therefore the function returns NULL from line 378.
Now in sys_timer_create() at line number 462
Process = NULL
Now at line 489
if (!process) becomes TRUE
and function returns with EINVAL
Is my analysis right? If so can you comment on this behaviour?
-Aniruddha
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This archive was generated by hypermail 2b29 : Wed May 07 2003 - 22:00:21 EST