SUNRPC: Simplify synopsis of svc_pool_for_cpu()

Clean up: There is one caller. The @cpu argument can be made
implicit now that a get_cpu/put_cpu pair is no longer needed.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

include/linux/sunrpc/svc.h

@@ -504,7 +504,7 @@ int		   svc_register(const struct svc_serv *, struct net *, const int,
 
 void		   svc_wake_up(struct svc_serv *);
 void		   svc_reserve(struct svc_rqst *rqstp, int space);
-struct svc_pool *  svc_pool_for_cpu(struct svc_serv *serv, int cpu);
+struct svc_pool   *svc_pool_for_cpu(struct svc_serv *serv);
 char *		   svc_print_addr(struct svc_rqst *, char *, size_t);
 const char *	   svc_proc_name(const struct svc_rqst *rqstp);
 int		   svc_encode_result_payload(struct svc_rqst *rqstp,

net/sunrpc/svc.c

@@ -356,15 +356,21 @@ svc_pool_map_set_cpumask(struct task_struct *task, unsigned int pidx)
 	}
 }
 
-/*
- * Use the mapping mode to choose a pool for a given CPU.
- * Used when enqueueing an incoming RPC.  Always returns
- * a non-NULL pool pointer.
+/**
+ * svc_pool_for_cpu - Select pool to run a thread on this cpu
+ * @serv: An RPC service
+ *
+ * Use the active CPU and the svc_pool_map's mode setting to
+ * select the svc thread pool to use. Once initialized, the
+ * svc_pool_map does not change.
+ *
+ * Return value:
+ *   A pointer to an svc_pool
  */
-struct svc_pool *
-svc_pool_for_cpu(struct svc_serv *serv, int cpu)
+struct svc_pool *svc_pool_for_cpu(struct svc_serv *serv)
 {
 	struct svc_pool_map *m = &svc_pool_map;
+	int cpu = raw_smp_processor_id();
 	unsigned int pidx = 0;
 
 	if (serv->sv_nrpools <= 1)

net/sunrpc/svc_xprt.c

@@ -460,7 +460,7 @@ void svc_xprt_enqueue(struct svc_xprt *xprt)
 	if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags))
 		return;
 
-	pool = svc_pool_for_cpu(xprt->xpt_server, raw_smp_processor_id());
+	pool = svc_pool_for_cpu(xprt->xpt_server);
 
 	atomic_long_inc(&pool->sp_stats.packets);