From 0ac24c320c4d89a9de6ec802591398b8675c7b3c Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Tue, 9 Feb 2021 10:48:57 -0500 Subject: svcrdma: Hold private mutex while invoking rdma_accept() RDMA core mutex locking was restructured by commit d114c6feedfe ("RDMA/cma: Add missing locking to rdma_accept()") [Aug 2020]. When lock debugging is enabled, the RPC/RDMA server trips over the new lockdep assertion in rdma_accept() because it doesn't call rdma_accept() from its CM event handler. As a temporary fix, have svc_rdma_accept() take the handler_mutex explicitly. In the meantime, let's consider how to restructure the RPC/RDMA transport to invoke rdma_accept() from the proper context. Calls to svc_rdma_accept() are serialized with calls to svc_rdma_free() by the generic RPC server layer. Suggested-by: Jason Gunthorpe Link: https://lore.kernel.org/linux-rdma/20210209154014.GO4247@nvidia.com/ Fixes: d114c6feedfe ("RDMA/cma: Add missing locking to rdma_accept()") Signed-off-by: Chuck Lever --- net/sunrpc/xprtrdma/svc_rdma_transport.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'net') diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c index afba4e9d5425..c895f80df659 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c @@ -475,9 +475,6 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt) if (!svc_rdma_post_recvs(newxprt)) goto errout; - /* Swap out the handler */ - newxprt->sc_cm_id->event_handler = svc_rdma_cma_handler; - /* Construct RDMA-CM private message */ pmsg.cp_magic = rpcrdma_cmp_magic; pmsg.cp_version = RPCRDMA_CMP_VERSION; @@ -498,7 +495,10 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt) } conn_param.private_data = &pmsg; conn_param.private_data_len = sizeof(pmsg); + rdma_lock_handler(newxprt->sc_cm_id); + newxprt->sc_cm_id->event_handler = svc_rdma_cma_handler; ret = rdma_accept(newxprt->sc_cm_id, &conn_param); + rdma_unlock_handler(newxprt->sc_cm_id); if (ret) { trace_svcrdma_accept_err(newxprt, ret); goto errout; -- cgit v1.2.3-70-g09d2