Manual Pages for UNIX Operating System command usage for man ddi_periodic_delete

Kernel Functions for Drivers              ddi_periodic_delete(9F)



NAME
     ddi_periodic_delete -  cancel  nanosecond  periodic  timeout
     requests

SYNOPSIS
     #include 
     #include 

     void ddi_periodic_delete(ddi_periodic_t req);


INTERFACE LEVEL
     Solaris DDI specific (Solaris DDI)

PARAMETERS
     req    ddi_periodic_t    opaque    value     returned     by
            ddi_periodic_add(9F)


DESCRIPTION
     The    ddi_periodic_delete()    function     cancels     the
     ddi_periodic_add(9F) request that was previously issued.


     As with untimeout(9F), calling ddi_periodic_delete() against
     a  periodic  timeout  request  which  is  either  running on
     another CPU, or has already been canceled  causes  no  prob-
     lems. Unlike untimeout(9F), there are no restrictions on the
     lock   which   might   be   held   across   the   call    to
     ddi_periodic_delete().

CONTEXT
     The ddi_periodic_delete() function may be called  from  user
     or kernel context.

EXAMPLES
     Example 1 Cancelling a timeout request


     In the following example,  the  device  driver  cancels  the
     timeout request by calling ddi_periodic_delete() against the
     request that was previously issued.


       /*
       * Stop the periodic timer
       */
       static void
       stop_periodic_timer(struct my_state *statep)
       {
                ddi_periodic_delete(statep->periodic_id);
                delay(1); /* wait for one tick */



SunOS 5.11           Last change: 6 May 2009                    1






Kernel Functions for Drivers              ddi_periodic_delete(9F)



                mutex_destory(&statep->lock);
       }

       static void
       start_periodic_timer(struct my_state *statep)
       {
                hrtime_t interval = CHECK_INTERVAL;

                mutex_init(&statep->lock, NULL, MUTEX_DRIVER,
                    (void *)DDI_IPL_0);

                /*
                 * Register my_callback which is invoked periodically
                 * in CHECK_INTERVAL in kernel context.
                 */
                statep->periodic_id = ddi_periodic_add(my_periodic_func,
                    statep, interval, DDI_IPL_0);
       }

       static void
       my_periodic_func(void *arg)
       {
                  /*
                   * This handler is invoked periodically.
                   */
                  struct my_state *statep = (struct my_state *)arg;

                  mutex_enter(&statep->lock);
                  if (load_unbalanced(statep)) {
                      balance_tasks(statep);
                  }
                  mutex_exit(&statep->lock);
       }


SEE ALSO
     cv_timedwait(9F),                      ddi_intr_get_pri(9F),
     ddi_periodic_add(9F),      delay(9F),      drv_usectohz(9F),
     qtimeout(9F), quntimeout(9F), timeout(9F), untimeout(9F)

NOTES
     There might be a race  between  a  callback  invocation  and
     ddi_periodic_delete(). A device driver should take a respon-
     sibility for this avoidance if needed by  using  the  kernel
     synchronization such as a mutex lock or calling delay(9F) as
     in the example above.









SunOS 5.11           Last change: 6 May 2009                    2