close() Entry Point (Block Drivers)

The close(9E) entry point uses the same arguments as open(9E) with one exception. dev is the device number rather than a pointer to the device number.

The close() routine should verify otyp in the same way as was described for the open(9E) entry point. In the following example, close() must determine when the device can really be closed. Closing is affected by the number of block opens and layered opens.

Example 16–3 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);
}