/*
* This is a single linked list that chains all the "struct epitem" that
- * happened while transfering ready events to userspace w/out
+ * happened while transferring ready events to userspace w/out
* holding ->lock.
*/
struct epitem *ovflist;
spin_lock_init(&ncalls->lock);
}
+/**
+ * ep_events_available - Checks if ready events might be available.
+ *
+ * @ep: Pointer to the eventpoll context.
+ *
+ * Returns: Returns a value different than zero if ready events are available,
+ * or zero otherwise.
+ */
+static inline int ep_events_available(struct eventpoll *ep)
+{
+ return !list_empty(&ep->rdllist) || ep->ovflist != EP_UNACTIVE_PTR;
+}
+
/**
* ep_call_nested - Perform a bound (possibly) nested call, by checking
* that the recursion limit is not exceeded, and that
* We do not need to hold "ep->mtx" here because the epoll file
* is on the way to be removed and no one has references to it
* anymore. The only hit might come from eventpoll_release_file() but
- * holding "epmutex" is sufficent here.
+ * holding "epmutex" is sufficient here.
*/
mutex_lock(&epmutex);
/*
* We don't want to get "file->f_lock" because it is not
* necessary. It is not necessary because we're in the "struct file"
- * cleanup path, and this means that noone is using this file anymore.
+ * cleanup path, and this means that no one is using this file anymore.
* So, for example, epoll_ctl() cannot hit here since if we reach this
* point, the file counter already went to zero and fget() would fail.
* The only hit might come from ep_free() but by holding the mutex
* Trigger mode, we need to insert back inside
* the ready list, so that the next call to
* epoll_wait() will check again the events
- * availability. At this point, noone can insert
+ * availability. At this point, no one can insert
* into ep->rdllist besides us. The epoll_ctl()
* callers are locked out by
* ep_scan_ready_list() holding "mtx" and the
return timespec_add_safe(now, ts);
}
+/**
+ * ep_poll - Retrieves ready events, and delivers them to the caller supplied
+ * event buffer.
+ *
+ * @ep: Pointer to the eventpoll context.
+ * @events: Pointer to the userspace buffer where the ready events should be
+ * stored.
+ * @maxevents: Size (in terms of number of events) of the caller event buffer.
+ * @timeout: Maximum timeout for the ready events fetch operation, in
+ * milliseconds. If the @timeout is zero, the function will not block,
+ * while if the @timeout is less than zero, the function will block
+ * until at least one event has been retrieved (or an error
+ * occurred).
+ *
+ * Returns: Returns the number of ready events which have been fetched, or an
+ * error code, in case of error.
+ */
static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
int maxevents, long timeout)
{
- int res, eavail, timed_out = 0;
+ int res = 0, eavail, timed_out = 0;
unsigned long flags;
- long slack;
+ long slack = 0;
wait_queue_t wait;
ktime_t expires, *to = NULL;
to = &expires;
*to = timespec_to_ktime(end_time);
} else if (timeout == 0) {
+ /*
+ * Avoid the unnecessary trip to the wait queue loop, if the
+ * caller specified a non blocking operation.
+ */
timed_out = 1;
+ spin_lock_irqsave(&ep->lock, flags);
+ goto check_events;
}
-retry:
+fetch_events:
spin_lock_irqsave(&ep->lock, flags);
- res = 0;
- if (list_empty(&ep->rdllist)) {
+ if (!ep_events_available(ep)) {
/*
* We don't have any available event to return to the caller.
* We need to sleep here, and we will be wake up by
* to TASK_INTERRUPTIBLE before doing the checks.
*/
set_current_state(TASK_INTERRUPTIBLE);
- if (!list_empty(&ep->rdllist) || timed_out)
+ if (ep_events_available(ep) || timed_out)
break;
if (signal_pending(current)) {
res = -EINTR;
set_current_state(TASK_RUNNING);
}
+check_events:
/* Is it worth to try to dig for events ? */
- eavail = !list_empty(&ep->rdllist) || ep->ovflist != EP_UNACTIVE_PTR;
+ eavail = ep_events_available(ep);
spin_unlock_irqrestore(&ep->lock, flags);
*/
if (!res && eavail &&
!(res = ep_send_events(ep, events, maxevents)) && !timed_out)
- goto retry;
+ goto fetch_events;
return res;
}