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

[Jeff Layton <jlayton@kernel.org>]

On Tue, 2026-10-20 at 10:14 +0300, Avi Weiss wrote:
> 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

Reviewed-by: Jeff Layton <jlayton@kernel.org>