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SUNRPC/xprtrdma: Fix reconnection locking 

The xprtrdma client code currently relies on the task that initiated the
connect to hold the XPRT_LOCK for the duration of the connection
attempt. If the task is woken early, due to some other event, then that
lock could get released early.
Avoid races by using the same mechanism that the socket code uses of
transferring lock ownership to the RDMA connect worker itself. That
frees us to call rpcrdma_xprt_disconnect() directly since we're now
guaranteed exclusion w.r.t. other callers.

Fixes: 4cf44be6f1 ("xprtrdma: Fix recursion into rpcrdma_xprt_disconnect()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Trond Myklebust 2021-07-26 08:03:12 -04:00 committed by Anna Schumaker
parent e26d997272
commit f99fa50880
2 changed files with 7 additions and 6 deletions
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2
net/sunrpc/xprt.c
View File

@ -877,6 +877,7 @@ out:
spin_unlock(&xprt->transport_lock);
return ret;
}
EXPORT_SYMBOL_GPL(xprt_lock_connect);
void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
{
@ -893,6 +894,7 @@ out:
spin_unlock(&xprt->transport_lock);
wake_up_bit(&xprt->state, XPRT_LOCKED);
}
EXPORT_SYMBOL_GPL(xprt_unlock_connect);
/**
* xprt_connect - schedule a transport connect operation

11
net/sunrpc/xprtrdma/transport.c
View File

@ -250,12 +250,9 @@ xprt_rdma_connect_worker(struct work_struct *work)
xprt->stat.connect_start;
xprt_set_connected(xprt);
rc = -EAGAIN;
} else {
/* Force a call to xprt_rdma_close to clean up */
spin_lock(&xprt->transport_lock);
set_bit(XPRT_CLOSE_WAIT, &xprt->state);
spin_unlock(&xprt->transport_lock);
}
} else
rpcrdma_xprt_disconnect(r_xprt);
xprt_unlock_connect(xprt, r_xprt);
xprt_wake_pending_tasks(xprt, rc);
}
@ -489,6 +486,8 @@ xprt_rdma_connect(struct rpc_xprt *xprt, struct rpc_task *task)
struct rpcrdma_ep *ep = r_xprt->rx_ep;
unsigned long delay;
WARN_ON_ONCE(!xprt_lock_connect(xprt, task, r_xprt));
delay = 0;
if (ep && ep->re_connect_status != 0) {
delay = xprt_reconnect_delay(xprt);