Commit 8446487f authored by David Howells's avatar David Howells

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: default avatarDavid Howells <dhowells@redhat.com>
parent b667b867
......@@ -328,10 +328,12 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to)
spin_lock_irq(&pipe->wait.lock);
tail++;
pipe->tail = tail;
do_wakeup = 0;
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);
if (head - (tail - 1) == pipe->max_usage)
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
}
total_len -= chars;
......@@ -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);
......
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