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-rw-r--r--fs/pipe.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/fs/pipe.c b/fs/pipe.c
index 9873a6030..aa8e6ffe1 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -424,6 +424,18 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
bool was_empty = false;
bool wake_next_writer = false;
+ /*
+ * Reject writing to watch queue pipes before the point where we lock
+ * the pipe.
+ * Otherwise, lockdep would be unhappy if the caller already has another
+ * pipe locked.
+ * If we had to support locking a normal pipe and a notification pipe at
+ * the same time, we could set up lockdep annotations for that, but
+ * since we don't actually need that, it's simpler to just bail here.
+ */
+ if (pipe_has_watch_queue(pipe))
+ return -EXDEV;
+
/* Null write succeeds. */
if (unlikely(total_len == 0))
return 0;
@@ -436,11 +448,6 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
goto out;
}
- if (pipe_has_watch_queue(pipe)) {
- ret = -EXDEV;
- goto out;
- }
-
/*
* If it wasn't empty we try to merge new data into
* the last buffer.