pollwakeup(D3)pollwakeup(D3)NAMEpollwakeup - inform polling processes that an event has occurred
SYNOPSIS
#include <sys/poll.h>
#include <sys/ddi.h>
void pollwakeup(struct pollhead *php, short event);
Arguments
php Pointer to a pollhead structure.
event Event to notify the process about.
DESCRIPTION
The pollwakeup function provides non-STREAMS character drivers with a way
to notify processes polling for the occurrence of an event.
Return Values
None
USAGEpollwakeup should be called from the driver for each occurrence of an
event. Events are described in poll(D2).
The pollhead structure will usually be associated with the driver's
private data structure for the particular minor device where the event
has occurred.
pollwakeup should only be called with one event at a time.
Level
Base or Interrupt.
Synchronization Constraints
Does not sleep.
Driver-defined basic locks, read/write locks, and sleep locks may be held
across calls to this function.
Note that the portions of the driver which implement the driver's poll()
routine and the lower layer which calls pollwakeup must agree on some
fundamental synchronization between themselves. Often this will be done
via a lock to prevent the lower layer interrupt code and upper layer poll
routine from manipulating state bits simultaneously or examining
inconsistent state. Of particular import is the poll() routine's
snapshot of the driver's pollhead generation number (if the driver has a
pollhead). This snapshot must occur either within the inter-locked code
in the poll() routine to hold off any call to pollwakeup in the lower
layer, or it must be done before any event state is examined if there is
no inter-lock between the high and low layers of the driver. Of similar
concern, the lower level layer must either call pollwakeup within an
interlocked synchronization section or must call after all device state
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pollwakeup(D3)pollwakeup(D3)
queried by the poll() routine has been updated. See poll(D2) for an
explanation of the race condition that is detected by this rule.
REFERENCESpoll(2), poll(D2)
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