SUNRPC: Always manipulate rpc_rqst::rq_bc_pa_list under xprt->bc_pa_lock

Other code that accesses rq_bc_pa_list holds xprt->bc_pa_lock.
xprt_complete_bc_request() should do the same.

Fixes: 2ea24497a1b3 ("SUNRPC: RPC callbacks may be split . . .")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/sunrpc/backchannel_rqst.c b/net/sunrpc/backchannel_rqst.c
index 651f49ab601f..9dd0ea8db463 100644
--- a/net/sunrpc/backchannel_rqst.c
+++ b/net/sunrpc/backchannel_rqst.c
@@ -309,12 +309,15 @@ void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
         struct rpc_xprt *xprt = req->rq_xprt;
         struct svc_serv *bc_serv = xprt->bc_serv;
 
+        spin_lock(&xprt->bc_pa_lock);
+        list_del(&req->rq_bc_pa_list);
+        spin_unlock(&xprt->bc_pa_lock);
+
         req->rq_private_buf.len = copied;
         set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
 
         dprintk("RPC:       add callback request to list\n");
         spin_lock(&bc_serv->sv_cb_lock);
-        list_del(&req->rq_bc_pa_list);
         list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
         wake_up(&bc_serv->sv_cb_waitq);
         spin_unlock(&bc_serv->sv_cb_lock);