diff options
| author | David Howells <dhowells@redhat.com> | 2019-09-24 16:07:04 +0100 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2019-11-15 16:22:54 +0000 |
| commit | 8446487feba988a92e7649c60367510f0b0445a8 (patch) | |
| tree | 01cd1b646eef48374f50c10fd0cd35792854ffd1 | |
| parent | b667b867344301e24f21d4a4c844675ff61d89e1 (diff) | |
pipe: Conditionalise wakeup in pipe_read()
Only do a wakeup in pipe_read() if we made space in a completely full
buffer. The producer shouldn't be waiting on pipe->wait otherwise.
Signed-off-by: David Howells <dhowells@redhat.com>
| -rw-r--r-- | fs/pipe.c | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index ea134f69a292..c16950e36ded 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -328,11 +328,13 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) spin_lock_irq(&pipe->wait.lock); tail++; pipe->tail = tail; - do_wakeup = 0; - wake_up_interruptible_sync_poll_locked( - &pipe->wait, EPOLLOUT | EPOLLWRNORM); + do_wakeup = 1; + if (head - (tail - 1) == pipe->max_usage) + wake_up_interruptible_sync_poll_locked( + &pipe->wait, EPOLLOUT | EPOLLWRNORM); spin_unlock_irq(&pipe->wait.lock); - kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); + if (head - (tail - 1) == pipe->max_usage) + kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); } total_len -= chars; if (!total_len) @@ -361,11 +363,6 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) ret = -ERESTARTSYS; break; } - if (do_wakeup) { - wake_up_interruptible_sync_poll(&pipe->wait, EPOLLOUT | EPOLLWRNORM); - kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); - do_wakeup = 0; - } pipe_wait(pipe); } __pipe_unlock(pipe); |