summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--fs/eventpoll.c24
-rw-r--r--include/uapi/linux/eventpoll.h3
2 files changed, 24 insertions, 3 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 1e009cad8d5c..ae1dbcf47e97 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -92,7 +92,7 @@
*/
/* Epoll private bits inside the event mask */
-#define EP_PRIVATE_BITS (EPOLLWAKEUP | EPOLLONESHOT | EPOLLET)
+#define EP_PRIVATE_BITS (EPOLLWAKEUP | EPOLLONESHOT | EPOLLET | EPOLLEXCLUSIVE)
/* Maximum number of nesting allowed inside epoll sets */
#define EP_MAX_NESTS 4
@@ -1002,6 +1002,7 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k
unsigned long flags;
struct epitem *epi = ep_item_from_wait(wait);
struct eventpoll *ep = epi->ep;
+ int ewake = 0;
if ((unsigned long)key & POLLFREE) {
ep_pwq_from_wait(wait)->whead = NULL;
@@ -1066,8 +1067,10 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k
* Wake up ( if active ) both the eventpoll wait list and the ->poll()
* wait list.
*/
- if (waitqueue_active(&ep->wq))
+ if (waitqueue_active(&ep->wq)) {
+ ewake = 1;
wake_up_locked(&ep->wq);
+ }
if (waitqueue_active(&ep->poll_wait))
pwake++;
@@ -1078,6 +1081,9 @@ out_unlock:
if (pwake)
ep_poll_safewake(&ep->poll_wait);
+ if (epi->event.events & EPOLLEXCLUSIVE)
+ return ewake;
+
return 1;
}
@@ -1095,7 +1101,10 @@ static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
pwq->whead = whead;
pwq->base = epi;
- add_wait_queue(whead, &pwq->wait);
+ if (epi->event.events & EPOLLEXCLUSIVE)
+ add_wait_queue_exclusive(whead, &pwq->wait);
+ else
+ add_wait_queue(whead, &pwq->wait);
list_add_tail(&pwq->llink, &epi->pwqlist);
epi->nwait++;
} else {
@@ -1862,6 +1871,15 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
goto error_tgt_fput;
/*
+ * epoll adds to the wakeup queue at EPOLL_CTL_ADD time only,
+ * so EPOLLEXCLUSIVE is not allowed for a EPOLL_CTL_MOD operation.
+ * Also, we do not currently supported nested exclusive wakeups.
+ */
+ if ((epds.events & EPOLLEXCLUSIVE) && (op == EPOLL_CTL_MOD ||
+ (op == EPOLL_CTL_ADD && is_file_epoll(tf.file))))
+ goto error_tgt_fput;
+
+ /*
* At this point it is safe to assume that the "private_data" contains
* our own data structure.
*/
diff --git a/include/uapi/linux/eventpoll.h b/include/uapi/linux/eventpoll.h
index bc81fb2e1f0e..1c3154913a39 100644
--- a/include/uapi/linux/eventpoll.h
+++ b/include/uapi/linux/eventpoll.h
@@ -26,6 +26,9 @@
#define EPOLL_CTL_DEL 2
#define EPOLL_CTL_MOD 3
+/* Set exclusive wakeup mode for the target file descriptor */
+#define EPOLLEXCLUSIVE (1 << 28)
+
/*
* Request the handling of system wakeup events so as to prevent system suspends
* from happening while those events are being processed.