pipe: use event aware wakeups

Send the events the wakeup refers to, so that epoll, and even the new poll
code in fs/select.c can avoid wakeups if the events do not match the
requested set.

Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/pipe.c

@@ -441,7 +441,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
 			break;
 		}
 		if (do_wakeup) {
-			wake_up_interruptible_sync(&pipe->wait);
+			wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT);
  			kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 		}
 		pipe_wait(pipe);
@@ -450,7 +450,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
 
 	/* Signal writers asynchronously that there is more room. */
 	if (do_wakeup) {
-		wake_up_interruptible_sync(&pipe->wait);
+		wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT);
 		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 	}
 	if (ret > 0)
@@ -612,7 +612,7 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
 			break;
 		}
 		if (do_wakeup) {
-			wake_up_interruptible_sync(&pipe->wait);
+			wake_up_interruptible_sync_poll(&pipe->wait, POLLIN);
 			kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 			do_wakeup = 0;
 		}
@@ -623,7 +623,7 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
 out:
 	mutex_unlock(&inode->i_mutex);
 	if (do_wakeup) {
-		wake_up_interruptible_sync(&pipe->wait);
+		wake_up_interruptible_sync_poll(&pipe->wait, POLLIN);
 		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 	}
 	if (ret > 0)
@@ -715,7 +715,7 @@ pipe_release(struct inode *inode, int decr, int decw)
 	if (!pipe->readers && !pipe->writers) {
 		free_pipe_info(inode);
 	} else {
-		wake_up_interruptible_sync(&pipe->wait);
+		wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLOUT);
 		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 	}