ddi_periodic_delete(9f) [opensolaris man page]

ddi_periodic_delete(9F) 				   Kernel Functions for Drivers 				   ddi_periodic_delete(9F)

NAME

       ddi_periodic_delete - cancel nanosecond periodic timeout requests

SYNOPSIS

       #include <sys/dditypes.h>
       #include <sys/sunddi.h>

       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 problems. 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 pre-
       viously issued.

	 /*
	 * Stop the periodic timer
	 */
	 static void
	 stop_periodic_timer(struct my_state *statep)
	 {
		  ddi_periodic_delete(statep->periodic_id);
		  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)

SunOS 5.11							    2 Oct 2007						   ddi_periodic_delete(9F)

untimeout(9F)						   Kernel Functions for Drivers 					     untimeout(9F)

NAME

       untimeout - cancel previous timeout function call

SYNOPSIS

       #include <sys/types.h>
       #include <sys/conf.h>

       clock_t untimeout(timeout_id_t id);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       id	Opaque timeout ID from a previous timeout(9F) call.

DESCRIPTION

       untimeout() cancels a pending  timeout(9F) request. untimeout() will not return until the pending callback is cancelled or has run. Because
       of this, locks acquired by the callback routine should not be held across the call to untimeout() or a deadlock may result.

       Since no mutex should be held across the call to untimeout(), there is a race condition between the occurrence of an expected event and the
       execution  of  the  timeout  handler. In particular, it should be noted that no problems will result from calling untimeout() for a timeout
       which is either running on another CPU, or has already completed.  Drivers should be structured with the understanding that the arrival	of
       both an interrupt and a timeout for that interrupt can occasionally occur, in either order.

RETURN VALUES

       untimeout() returns -1 if the id is not found. Otherwise, it returns an integer value greater than or equal to 0.

CONTEXT

       untimeout() can be called from user or interrupt context.

EXAMPLES

       In  the	following  example,  the  device  driver has issued an IO request and is waiting for the device to respond. If the device does not
       respond within 5 seconds, the device driver will print out an error message to the console.

       static void
       xxtimeout_handler(void *arg)
       {
	       struct xxstate *xsp = (struct xxstate *)arg;
	       mutex_enter(&xsp->lock);
	       cv_signal(&xsp->cv);
	       xsp->flags |= TIMED_OUT;
	       mutex_exit(&xsp->lock);
	       xsp->timeout_id = 0;
       }
       static uint_t
       xxintr(caddr_t arg)
       {
	       struct xxstate *xsp = (struct xxstate *)arg;
		.
		.
		.
	       mutex_enter(&xsp->lock);
	       /* Service interrupt */
	       cv_signal(&xsp->cv);
	       mutex_exit(&xsp->lock);
	       if (xsp->timeout_id != 0) {
		       (void) untimeout(xsp->timeout_id);
		       xsp->timeout_id = 0;
	       }
	       return(DDI_INTR_CLAIMED);
       }
       static void
       xxcheckcond(struct xxstate *xsp)
       {
		.
		.
		.
	       xsp->timeout_id = timeout(xxtimeout_handler,
		   xsp, (5 * drv_usectohz(1000000)));
	       mutex_enter(&xsp->lock);
	       while (/* Waiting for interrupt	or timeout*/)
		       cv_wait(&xsp->cv, &xsp->lock);
	       if (xsp->flags & TIMED_OUT)
		       cmn_err(CE_WARN, "Device not responding");
		.
		.
		.
	       mutex_exit(&xsp->lock);
		.
		.
		.
       }

SEE ALSO

       open(9E), cv_signal(9F), cv_wait_sig(9F), delay(9F), timeout(9F)

       Writing Device Drivers

SunOS 5.10							    18 Feb 1998 						     untimeout(9F)