[PATCH] SUNRPC: wake poll waiters when an empty pipe is unlinked

[Avi Weiss <thnkslprpt@gmail.com>]

When an empty rpc_pipefs pipe is unlinked, rpc_purge_list() returns
without waking the pipe wait queue. An existing epoll waiter can
remain blocked even though rpc_pipe_poll() reports EPOLLHUP and
EPOLLERR for the disconnected pipe.

Wake the wait queue after clearing RPC_I(inode)->pipe so existing
poll waiters are notified regardless of whether messages were purged.

Fixes: 9842ef3557ab ("SUNRPC: rpc_timeout_upcall_queue should not sleep")
Signed-off-by: Avi Weiss <thnkslprpt@gmail.com>
---

Tested with an empty rpc_pipefs pipe in QEMU:
- 7.3.0 baseline: fresh poll() reports HUP/ERR (0x18),
  but an existing epoll_wait() times out.
- 7.3.0 with this patch: fresh poll() reports HUP/ERR (0x18),
  and epoll_wait() returns events=0x18.

 net/sunrpc/rpc_pipe.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index 9d349cfbc4831..68b4e040a77d9 100644
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -191,6 +191,7 @@ rpc_close_pipes(struct dentry *dentry)
 	cancel_delayed_work_sync(&pipe->queue_timeout);
 	rpc_inode_setowner(inode, NULL);
 	RPC_I(inode)->pipe = NULL;
+	wake_up(&RPC_I(inode)->waitq);
 	inode_unlock(inode);
 }
 

base-commit: c03c1a14507dfaf8b856c2608f9ac216021fc222
-- 
2.43.0