Petalinux pthread_create does not create new thread?

Question

The attached test program creates two detached threads. When I run the app and look at the processes in top, I cannot find individual entries for each thread. I tried typing H with top running, but this did not show me any additional information.
Does this mean that my pthreads are not being created as separate threads somehow?
A side effect of this is that if the ioctl call made by each thread is blocking, the entier process blocks until the ioctl returns, not just the thread that made the call. In the example below, I have worked around this by making the ioctl non-blocking, but now the process consumes the CPU, which is, of course, undesirable.
Thanks, in advance, for your help.
Well, for some reason, the system won't let me attach my source file, so here it is...
 * Placeholder PetaLinux user application.
 * Replace this with your application code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <net/if.h>
#include <pthread.h>
#define FP_IOCTL_CMD  SIOCDEVPRIVATE + 14
#define PPS_IOCTL_CMD SIOCDEVPRIVATE + 1
void* wait_for_frame_pulse(void* arg) {
  int sd;
  int ioctl_result = 0;
  unsigned short fod = 0;
  int flags;
  // setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, "ad160", 5);
  struct ifreq ifr;
  memset(&ifr, 0, sizeof(struct ifreq));
  if ((sd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
    printf("Socket error!\n");
    pthread_exit(NULL);
  flags = fcntl(sd, F_GETFL, 0);
  /* if (fcntl(sd, F_SETFL, O_NONBLOCK) < 0) { */
  /*   printf("fcntl error! %s\n", strerror(errno)); */
  /*   pthread_exit(NULL); */
  strcpy(ifr.ifr_name, "ad160");
  printf("About to start frame pulse waiting cycle.\n");
  while (1) {
    /* printf("Waiting for frame pulse: %d\n", fod%200); */
    while (ioctl(sd, FP_IOCTL_CMD, &ifr) == -1) {
      if (errno != EWOULDBLOCK) {
    printf("AD16NET FP IOCTL failed: %s\n", strerror(errno));
    pthread_exit (NULL);
    /* printf("%d: GOT A FRAME PULSE!\n", fod%200); */
    ++fod;
  pthread_exit(NULL);
void* wait_for_pulse_per_second(void* arg) {
  int sd;
  unsigned short sod = 0;
  int flags;
  // setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, "ad160", 5);
  struct ifreq ifr;
  memset(&ifr, 0, sizeof(struct ifreq));
  if ((sd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
    printf("Socket error!\n");
    pthread_exit(NULL);
  flags = fcntl(sd, F_GETFL, 0);
  /* if (fcntl(sd, F_SETFL, flags | O_NONBLOCK) < 0) { */
  /*   printf("fcntl error! %s\n", strerror(errno)); */
  /*   pthread_exit(NULL); */
  strcpy(ifr.ifr_name, "ad160");
  printf("About to start pulse per second waiting cycle.\n");
  while (1) {
    /* printf("Waiting for pulse per second: %d\n", sod); */
    while (ioctl(sd, PPS_IOCTL_CMD, &ifr) == -1) {
      if (errno != EWOULDBLOCK) {
    printf("AD16NET PPS IOCTL failed: %s\n", strerror(errno));
    pthread_exit (NULL);
    /* printf("%d: GOT A PPS!\n", sod); */
    ++sod;
  pthread_exit(NULL);
int main(int argc, char *argv[])
  int s, thread_id_pps, thread_id_fp;
  pthread_attr_t attr;
  struct timespec sleep_time;
  sleep_time.tv_sec = 1;
  sleep_time.tv_nsec = 0;
    printf("Hello, PetaLinux World!\n");
    printf("cmdline args:\n");
    while(argc--)
        printf("%s\n",*argv++);
    s = pthread_attr_init(&attr);
    if (s != 0) {
      perror("pthread_attr_init");
      exit(-1);
    s = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
    if (s != 0) {
      perror("pthread_attr_setdetachstate");
      exit(-1);
    s = pthread_create(&thread_id_fp,
               &attr,
               &wait_for_frame_pulse,
               NULL);
    if (s) {
      perror("pthread_create 1");
      exit (-1);
    s = pthread_create(&thread_id_pps,
               &attr,
               &wait_for_pulse_per_second,
               NULL);
    if (s) {
      perror("pthread_create 2");
      exit (-1);
    pthread_attr_destroy(&attr);
    /* wait_for_pulse_per_second(); */
    /* if (pthread_detach(thread_id_fp)) { */
    /*   perror("pthread_detach 1"); */
    /*   exit (-1); */
    /* if (pthread_detach(thread_id_pps)) { */
    /*   perror("pthread_detach 2"); */
    /*   exit (-1); */
#if 0
    int pid = fork();
    if (pid == 0) {
      wait_for_frame_pulse();
    else if (pid > 0) {
      wait_for_pulse_per_second();
    else {
      printf("fork() failed!\n");
      return 1;
#endif
    pthread_exit(NULL);
    /* while (1) {nanosleep(&sleep_time, NULL);} */
    /* return 0; */

Answer 1

Actually, that's what I did. I typed "H" while top was running. I just tried it again, and pasted the result, below. Pressing "H" only refreshes the display, nothing else. Also, when I type "top -H" I get the Usage statement, which tells me that the "-H" is not supported.
Also, since this is a network device, it doesn't appear that there is an option to do an "ioctl_unlocked". The only ioctl specified in struct net_device_ops is "ndo_do_ioctl."
Of course, being a newb, I could be missing something.
Mem: 36824K used, 995664K free, 0K shrd, 734928K buff, 734976K cached
CPU: 13.2% usr 83.6% sys  0.0% nic  3.0% idle  0.0% io  0.0% irq  0.0% sirq
Load average: 2.39 0.68 0.23 3/45 882
  PID  PPID USER     STAT   VSZ %VSZ CPU %CPU COMMAND
  877   873 root     Z        0  0.0   1 96.6 [AD16NET_test]
  873     1 root     S     2956  0.2   0  0.0 -sh
  882   873 root     R     2956  0.2   0  0.0 top
  817     1 root     S     2852  0.2   0  0.0 /sbin/inetd
  857     1 root     S     2764  0.2   0  0.0 udhcpc -R -b -p /var/run/udhcpc.et
  875     1 root     S     2764  0.2   1  0.0 /sbin/httpd -h /srv/www
    1     0 root     S     1860  0.1   0  0.0 init [5]
  393     2 root     RW       0  0.0   1  0.0 [kworker/1:1]
    6     2 root     SW       0  0.0   0  0.0 [kworker/u4:0]
   17     2 root     SW       0  0.0   0  0.0 [kworker/u4:1]
    7     2 root     SW       0  0.0   1  0.0 [rcu_preempt]
   49     2 root     SW       0  0.0   0  0.0 [kworker/0:1]
    2     0 root     SW       0  0.0   1  0.0 [kthreadd]
    3     2 root     SW       0  0.0   0  0.0 [ksoftirqd/0]
    4     2 root     SW       0  0.0   0  0.0 [kworker/0:0]
    5     2 root     SW<      0  0.0   0  0.0 [kworker/0:0H]
    8     2 root     SW       0  0.0   0  0.0 [rcu_sched]
    9     2 root     SW       0  0.0   0  0.0 [rcu_bh]
   10     2 root     SW       0  0.0   0  0.0 [migration/0]
   11     2 root     SW       0  0.0   1  0.0 [migration/1]