FreeBSD kernel module that unlock an unlinked fifo's locked threads

mysql_fifo_test.c

#include <sys/types.h>
#include <sys/module.h>
#include <sys/errno.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/types.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/fcntl.h>
#include <sys/vnode.h>
#include <sys/buf.h>
#include <sys/capability.h>
 
int link_vnode_at(struct thread *td, struct vnode *vp, char *path);
void mysql_fifo_test_main_thread(void *p);
 
static struct mtx main_thread_mutex;
static struct thread *main_thread;
 
void mysql_fifo_test_main_thread(void *p) {
  struct vop_vector *f;
  vop_open_t *fifo_open;
  vop_close_t *fifo_close;
 
  mtx_lock(&main_thread_mutex);
  printf("MySQL FIFO Test In da thread.\n");
 
  /* Get a pointer to the original open args */
  struct vop_open_args *ap;
  ap = (struct vop_open_args *) 0xfffffe0095f17678;
 
  /* Get pointers to the fifo ops functions */
  f = &fifo_specops;
  fifo_open = f->vop_open;
  fifo_close = f->vop_close;
 
  /* Call fifo_open */
  struct file some_file;
  struct vop_open_args ap_open;
  ap_open.a_vp = ap->a_vp;
  ap_open.a_mode = FWRITE;
  ap_open.a_cred = NULL; //unused in fifo_open
  ap_open.a_fp = &some_file;
  ap_open.a_td = main_thread;
  fifo_open(&ap_open);
 
  /* Call fifo_close */
  struct vop_close_args ap_close;
  ap_close.a_vp = ap->a_vp;
  ap_close.a_fflag = FWRITE;
  ap_close.a_cred = NULL; //unused in fifo_close
  ap_close.a_td = main_thread;
  fifo_close(&ap_close);
 
  mtx_unlock(&main_thread_mutex);
  kthread_exit();
}
 
static void
mysql_fifo_test_load() {
  mtx_init(&main_thread_mutex, "mysql_fifo_test_main_thread_mutex", NULL, MTX_DEF);
  mtx_lock(&main_thread_mutex);
 
  kthread_add(mysql_fifo_test_main_thread, NULL, NULL, &main_thread, 0, 0, "mysql_fifo_test_main_thread");
 
  mtx_unlock(&main_thread_mutex);
}
 
static void
mysql_fifo_test_unload() {
  mtx_lock(&main_thread_mutex);
  mtx_destroy(&main_thread_mutex);  
}
 
static int
mysql_fifo_test_loader(struct module *m, int what, void *arg)
{
  int err = 0;
 
  switch (what) {
  case MOD_LOAD:
    mysql_fifo_test_load();
    uprintf("MySQL FIFO Test loaded.\n");
    break;
  case MOD_UNLOAD:
    mysql_fifo_test_unload();
    uprintf("MySQL FIFO Test unloaded.\n");
    break;
  default:
    err = EOPNOTSUPP;
    break;
  }
  return(err);
}
 
static moduledata_t mysql_fifo_test_mod = {
  "mysql_fifo_test",
  mysql_fifo_test_loader,
  NULL
};
 
DECLARE_MODULE(mysql_fifo_test, mysql_fifo_test_mod, SI_SUB_KLD, SI_ORDER_ANY);