close(9E)

The arguments of the close(9E) entry point are identical to arguments of open(9E), except that dev is the device number, as opposed to a pointer to the device number.

The close(9E) routine should verify otyp in the same way as was described for the open(9E) entry point. In Example 11-3, close(9E) must determine when the device can really be closed based on the number of block opens and layered opens.

Example 11-3 Block Device close(9E) Routine

static int
xxclose(dev_t dev, int flag, int otyp, cred_t *credp)
{
     minor_t instance;
     struct xxstate *xsp;

     instance = getminor(dev);
     xsp = ddi_get_soft_state(statep, instance);
       if (xsp == NULL)
              return (ENXIO);
     mutex_enter(&xsp->mu);
     switch (otyp) {
       case OTYP_LYR:
           xsp->nlayered--;
           break;
      case OTYP_BLK:
           xsp->open = 0;
           break;
     default:
           mutex_exit(&xsp->mu);
           return (EINVAL);
       }

     if (xsp->open || xsp->nlayered) {
           /* not done yet */
           mutex_exit(&xsp->mu);
           return (0);
     }
       /* cleanup (rewind tape, free memory, etc.) */
   /* wait for I/O to drain */
     mutex_exit(&xsp->mu);

     return (0);
}