sunrpc: convert sp_task_pending flag to use atomic bitops

In a later patch, we'll want to be able to handle this flag without
holding the sp_lock. Change this field to an unsigned long flags
field, and declare a new flag in it that can be managed with atomic
bitops.
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

include/linux/sunrpc/svc.h

@@ -50,7 +50,9 @@ struct svc_pool {
 	unsigned int		sp_nrthreads;	/* # of threads in pool */
 	struct list_head	sp_all_threads;	/* all server threads */
 	struct svc_pool_stats	sp_stats;	/* statistics on pool operation */
-	int			sp_task_pending;/* has pending task */
+#define	SP_TASK_PENDING		(0)		/* still work to do even if no
+						 * xprt is queued. */
+	unsigned long		sp_flags;
 } ____cacheline_aligned_in_smp;
 
 /*

net/sunrpc/svc_xprt.c

@@ -509,7 +509,7 @@ void svc_wake_up(struct svc_serv *serv)
 			 */
 			wake_up_process(rqstp->rq_task);
 		} else
-			pool->sp_task_pending = 1;
+			set_bit(SP_TASK_PENDING, &pool->sp_flags);
 		spin_unlock_bh(&pool->sp_lock);
 	}
 }
@@ -644,10 +644,9 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
 		 * long for cache updates.
 		 */
 		rqstp->rq_chandle.thread_wait = 1*HZ;
-		pool->sp_task_pending = 0;
+		clear_bit(SP_TASK_PENDING, &pool->sp_flags);
 	} else {
-		if (pool->sp_task_pending) {
-			pool->sp_task_pending = 0;
+		if (test_and_clear_bit(SP_TASK_PENDING, &pool->sp_flags)) {
 			xprt = ERR_PTR(-EAGAIN);
 			goto out;
 		}