summaryrefslogtreecommitdiff
path: root/fs
diff options
context:
space:
mode:
Diffstat (limited to 'fs')
-rw-r--r--fs/pipe.c15
1 files changed, 9 insertions, 6 deletions
diff --git a/fs/pipe.c b/fs/pipe.c
index 8e6ef62aeb1c..678dee2a8228 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -444,9 +444,6 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
#endif
/*
- * Epoll nonsensically wants a wakeup whether the pipe
- * was already empty or not.
- *
* If it wasn't empty we try to merge new data into
* the last buffer.
*
@@ -455,9 +452,9 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
* spanning multiple pages.
*/
head = pipe->head;
- was_empty = true;
+ was_empty = pipe_empty(head, pipe->tail);
chars = total_len & (PAGE_SIZE-1);
- if (chars && !pipe_empty(head, pipe->tail)) {
+ if (chars && !was_empty) {
unsigned int mask = pipe->ring_size - 1;
struct pipe_buffer *buf = &pipe->bufs[(head - 1) & mask];
int offset = buf->offset + buf->len;
@@ -590,8 +587,11 @@ out:
* This is particularly important for small writes, because of
* how (for example) the GNU make jobserver uses small writes to
* wake up pending jobs
+ *
+ * Epoll nonsensically wants a wakeup whether the pipe
+ * was already empty or not.
*/
- if (was_empty) {
+ if (was_empty || pipe->poll_usage) {
wake_up_interruptible_sync_poll(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM);
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
}
@@ -654,6 +654,9 @@ pipe_poll(struct file *filp, poll_table *wait)
struct pipe_inode_info *pipe = filp->private_data;
unsigned int head, tail;
+ /* Epoll has some historical nasty semantics, this enables them */
+ pipe->poll_usage = 1;
+
/*
* Reading pipe state only -- no need for acquiring the semaphore.
*