xprt_autoclose() clears XPRT_CLOSE_WAIT before invoking the transport's ->close() operation. For RPC/RDMA, ->close() calls rpcrdma_xprt_disconnect(), which disconnects the RDMA CM endpoint and drains its QP. Since commit 31e62d25b5b8 ("xprtrdma: Simplify RPC wake-ups on connect"), RDMA_CM_EVENT_DISCONNECTED requests a SUNRPC transport disconnect. Today that path, along with failed completion handling, reaches xprt_force_disconnect() through rpcrdma_force_disconnect(). Commit c487eb7d8e41 ("xprtrdma: Clean up disconnect") later added re_force_disconnect to ensure that multiple failure indications request only one SUNRPC disconnect. However, the gate remains open when SUNRPC itself begins endpoint teardown. If re_force_disconnect is still clear, either a CM disconnect event or a completion error can set XPRT_CLOSE_WAIT again while the current close is in progress. When the transport send lock is subsequently released, xprt_clear_locked() observes XPRT_CLOSE_WAIT and queues another autoclose. Requesting a disconnect this way is necessary when a connection is lost unexpectedly, but not when the event was generated by rpcrdma_xprt_disconnect() itself. In that case SUNRPC is already committed to closing the transport. Mark re_force_disconnect before initiating local endpoint teardown so that CM events and completion errors caused by that teardown cannot request another close. An unexpected error that wins the race before local endpoint teardown begins can still request a disconnect normally. Use a fully ordered exchange so that the gate is globally closed before rdma_disconnect() can transition the QP to error and generate the callbacks that the gate suppresses. In 30-second traces of a sustained recovery loop, without this change there were 7,693 xprt_force_disconnect() calls, 6,267 SUNRPC autocloses, and 172,892 receive-side IB_WC_WR_FLUSH_ERR completions. With this change, the same tracepoints recorded 3,512 xprt_force_disconnect() calls, 3,212 autocloses, and 131,287 receive-side flush completions. Thus QP teardown continues to produce flushed completions, but closing the disconnect gate before teardown substantially reduces their feedback into the SUNRPC close path. Fixes: 31e62d25b5b8 ("xprtrdma: Simplify RPC wake-ups on connect") Cc: stable@vger.kernel.org Signed-off-by: Tim Menninger --- net/sunrpc/xprtrdma/verbs.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c index be335eed329d..54957295a631 100644 --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -114,9 +114,9 @@ static void rpcrdma_xprt_drain(struct rpcrdma_xprt *r_xprt) rpcrdma_ep_put(ep); } -/* Ensure xprt_force_disconnect() is invoked exactly once when a - * connection is closed or lost. (The important thing is it needs - * to be invoked "at least" once). +/* Ensure xprt_force_disconnect() is invoked at most once for an + * unexpected endpoint failure. Local endpoint teardown closes this + * gate before it can generate CM events and flushed completions. */ void rpcrdma_force_disconnect(struct rpcrdma_ep *ep) { @@ -587,6 +587,9 @@ void rpcrdma_xprt_disconnect(struct rpcrdma_xprt *r_xprt) if (!ep) return; + /* Prevent teardown-generated events from requesting another close. */ + atomic_xchg(&ep->re_force_disconnect, 1); + id = ep->re_id; rc = rdma_disconnect(id); trace_xprtrdma_disconnect(r_xprt, rc); -- 2.34.1