ddi_periodic_delete(9F) Kernel Functions for Drivers ddi_periodic_delete(9F)NAMEddi_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 previ‐
ously 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 */
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 ALSOcv_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_peri‐
odic_delete(). A device driver should take a responsibility 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 6 May 2009 ddi_periodic_delete(9F)
