diff options
| -rw-r--r-- | fs/pipe.c | 36 |
1 files changed, 29 insertions, 7 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index 87109e761fa5..04d004ee2e8c 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -364,17 +364,39 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) ret = -EAGAIN; break; } - if (signal_pending(current)) { - if (!ret) - ret = -ERESTARTSYS; - break; - } __pipe_unlock(pipe); - if (was_full) { + + /* + * We only get here if we didn't actually read anything. + * + * However, we could have seen (and removed) a zero-sized + * pipe buffer, and might have made space in the buffers + * that way. + * + * You can't make zero-sized pipe buffers by doing an empty + * write (not even in packet mode), but they can happen if + * the writer gets an EFAULT when trying to fill a buffer + * that already got allocated and inserted in the buffer + * array. + * + * So we still need to wake up any pending writers in the + * _very_ unlikely case that the pipe was full, but we got + * no data. + */ + if (unlikely(was_full)) { wake_up_interruptible_sync_poll(&pipe->wait, EPOLLOUT | EPOLLWRNORM); kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); } - wait_event_interruptible(pipe->wait, pipe_readable(pipe)); + + /* + * But because we didn't read anything, at this point we can + * just return directly with -ERESTARTSYS if we're interrupted, + * since we've done any required wakeups and there's no need + * to mark anything accessed. And we've dropped the lock. + */ + if (wait_event_interruptible(pipe->wait, pipe_readable(pipe)) < 0) + return -ERESTARTSYS; + __pipe_lock(pipe); was_full = pipe_full(pipe->head, pipe->tail, pipe->max_usage); } |