IB/srpt: Simplify srpt_shutdown_session()

The target core guarantees that shutdown_session() is only invoked
once per session. This means that the ib_srpt target driver doesn't
have to track whether or not shutdown_session() has been called.
Additionally, ensure that target_sess_cmd_list_set_waiting() is
called before target_wait_for_sess_cmds() by moving it into
srpt_release_channel_work().

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Cc: Alex Estrin <alex.estrin@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/srpt/ib_srpt.c

@@ -1892,20 +1892,7 @@ static void srpt_close_ch(struct srpt_rdma_ch *ch)
  */
 static int srpt_shutdown_session(struct se_session *se_sess)
 {
-	struct srpt_rdma_ch *ch = se_sess->fabric_sess_ptr;
-	unsigned long flags;
-
-	spin_lock_irqsave(&ch->spinlock, flags);
-	if (ch->in_shutdown) {
-		spin_unlock_irqrestore(&ch->spinlock, flags);
-		return true;
-	}
-
-	ch->in_shutdown = true;
-	target_sess_cmd_list_set_waiting(se_sess);
-	spin_unlock_irqrestore(&ch->spinlock, flags);
-
-	return true;
+	return 1;
 }
 
 /**
@@ -2008,6 +1995,7 @@ static void srpt_release_channel_work(struct work_struct *w)
 	se_sess = ch->sess;
 	BUG_ON(!se_sess);
 
+	target_sess_cmd_list_set_waiting(se_sess);
 	target_wait_for_sess_cmds(se_sess);
 
 	transport_deregister_session_configfs(se_sess);

drivers/infiniband/ulp/srpt/ib_srpt.h

@@ -286,7 +286,6 @@ struct srpt_rdma_ch {
 	u8			sess_name[36];
 	struct work_struct	release_work;
 	struct completion	*release_done;
-	bool			in_shutdown;
 };
 
 /**