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svcrdma: Hold private mutex while invoking rdma_accept()

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[ Upstream commit 0ac24c320c4d89a9de6ec802591398b8675c7b3c ]

RDMA core mutex locking was restructured by commit d114c6feed
("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 <jgg@nvidia.com>
Link: https://lore.kernel.org/linux-rdma/20210209154014.GO4247@nvidia.com/
Fixes: d114c6feed ("RDMA/cma: Add missing locking to rdma_accept()")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Chuck Lever 2021-02-09 10:48:57 -05:00 committed by Greg Kroah-Hartman
parent 7c7cb07d4a
commit 426b8fb3d6
1 changed files with 3 additions and 3 deletions
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6
net/sunrpc/xprtrdma/svc_rdma_transport.c
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@ -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;