IB/mad: Issue complete whenever decrements agent refcount

Replace calls of atomic_dec() to mad_agent_priv->refcount with calls to
deref_mad_agent() in order to issue complete. Most likely the refcount is
> 1 at these points, but it is difficult to prove. Performance is not
important on these paths, so be obviously correct.

Link: https://lore.kernel.org/r/20200621104738.54850-3-leon@kernel.orgSigned-off-by: Shay Drory <shayd@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/mad.c

@@ -1148,7 +1148,7 @@ int ib_post_send_mad(struct ib_mad_send_buf *send_buf,
 			spin_lock_irqsave(&mad_agent_priv->lock, flags);
 			list_del(&mad_send_wr->agent_list);
 			spin_unlock_irqrestore(&mad_agent_priv->lock, flags);
-			atomic_dec(&mad_agent_priv->refcount);
+			deref_mad_agent(mad_agent_priv);
 			goto error;
 		}
 	}
@@ -1831,7 +1831,7 @@ static void ib_mad_complete_recv(struct ib_mad_agent_private *mad_agent_priv,
 				mad_agent_priv->agent.recv_handler(
 						&mad_agent_priv->agent, NULL,
 						mad_recv_wc);
-				atomic_dec(&mad_agent_priv->refcount);
+				deref_mad_agent(mad_agent_priv);
 			} else {
 				/* not user rmpp, revert to normal behavior and
 				 * drop the mad */
@@ -1848,7 +1848,7 @@ static void ib_mad_complete_recv(struct ib_mad_agent_private *mad_agent_priv,
 					&mad_agent_priv->agent,
 					&mad_send_wr->send_buf,
 					mad_recv_wc);
-			atomic_dec(&mad_agent_priv->refcount);
+			deref_mad_agent(mad_agent_priv);
 
 			mad_send_wc.status = IB_WC_SUCCESS;
 			mad_send_wc.vendor_err = 0;
@@ -2438,7 +2438,7 @@ static void cancel_mads(struct ib_mad_agent_private *mad_agent_priv)
 		list_del(&mad_send_wr->agent_list);
 		mad_agent_priv->agent.send_handler(&mad_agent_priv->agent,
 						   &mad_send_wc);
-		atomic_dec(&mad_agent_priv->refcount);
+		deref_mad_agent(mad_agent_priv);
 	}
 }
 
@@ -2572,7 +2572,7 @@ static void local_completions(struct work_struct *work)
 						&local->mad_send_wr->send_buf,
 						&local->mad_priv->header.recv_wc);
 			spin_lock_irqsave(&recv_mad_agent->lock, flags);
-			atomic_dec(&recv_mad_agent->refcount);
+			deref_mad_agent(recv_mad_agent);
 			spin_unlock_irqrestore(&recv_mad_agent->lock, flags);
 		}
 
@@ -2585,7 +2585,7 @@ static void local_completions(struct work_struct *work)
 						   &mad_send_wc);
 
 		spin_lock_irqsave(&mad_agent_priv->lock, flags);
-		atomic_dec(&mad_agent_priv->refcount);
+		deref_mad_agent(mad_agent_priv);
 		if (free_mad)
 			kfree(local->mad_priv);
 		kfree(local);
@@ -2671,7 +2671,7 @@ static void timeout_sends(struct work_struct *work)
 		mad_agent_priv->agent.send_handler(&mad_agent_priv->agent,
 						   &mad_send_wc);
 
-		atomic_dec(&mad_agent_priv->refcount);
+		deref_mad_agent(mad_agent_priv);
 		spin_lock_irqsave(&mad_agent_priv->lock, flags);
 	}
 	spin_unlock_irqrestore(&mad_agent_priv->lock, flags);