SUNRPC: Don't dereference xprt->snd_task if it's a cookie

Fixes: e26d9972 ("SUNRPC: Clean up scheduling of autoclose")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

include/trace/events/sunrpc.h

@@ -965,7 +965,8 @@ TRACE_EVENT(rpc_socket_nospace,
 		{ BIT(XPRT_REMOVE),		"REMOVE" },		\
 		{ BIT(XPRT_CONGESTED),		"CONGESTED" },		\
 		{ BIT(XPRT_CWND_WAIT),		"CWND_WAIT" },		\
-		{ BIT(XPRT_WRITE_SPACE),	"WRITE_SPACE" })
+		{ BIT(XPRT_WRITE_SPACE),	"WRITE_SPACE" },	\
+		{ BIT(XPRT_SND_IS_COOKIE),	"SND_IS_COOKIE" })
 
 DECLARE_EVENT_CLASS(rpc_xprt_lifetime_class,
 	TP_PROTO(
@@ -1162,8 +1163,11 @@ DECLARE_EVENT_CLASS(xprt_writelock_event,
 			__entry->task_id = -1;
 			__entry->client_id = -1;
 		}
-		__entry->snd_task_id = xprt->snd_task ?
-					xprt->snd_task->tk_pid : -1;
+		if (xprt->snd_task &&
+		    !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
+			__entry->snd_task_id = xprt->snd_task->tk_pid;
+		else
+			__entry->snd_task_id = -1;
 	),
 
 	TP_printk(SUNRPC_TRACE_TASK_SPECIFIER
@@ -1208,8 +1212,12 @@ DECLARE_EVENT_CLASS(xprt_cong_event,
 			__entry->task_id = -1;
 			__entry->client_id = -1;
 		}
-		__entry->snd_task_id = xprt->snd_task ?
-					xprt->snd_task->tk_pid : -1;
+		if (xprt->snd_task &&
+		    !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
+			__entry->snd_task_id = xprt->snd_task->tk_pid;
+		else
+			__entry->snd_task_id = -1;
+
 		__entry->cong = xprt->cong;
 		__entry->cwnd = xprt->cwnd;
 		__entry->wait = test_bit(XPRT_CWND_WAIT, &xprt->state);