From 3b57c21ef9d0c434968798338292d14ab61290d4 Mon Sep 17 00:00:00 2001
From: =?utf8?q?N=C3=A9lio=20Laranjeiro?= <nelio.laranjeiro@6wind.com>
Date: Tue, 11 Apr 2017 17:21:52 +0200
Subject: [PATCH] net/mlx5: panic when destroying a queue in use

Since the queue release API does not allow failures (return value is void)
and the flow API does not allow a queue to be released as long as a flow
rule depends on it, the only rational decision to avoid undefined behavior
is to panic in this situation.

Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
---
 drivers/net/mlx5/mlx5.h      |  1 +
 drivers/net/mlx5/mlx5_flow.c | 31 +++++++++++++++++++++++++++++++
 drivers/net/mlx5/mlx5_rxq.c  |  4 ++++
 3 files changed, 36 insertions(+)

diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
index e8bf3612cf..71e19ec53e 100644
--- a/drivers/net/mlx5/mlx5.h
+++ b/drivers/net/mlx5/mlx5.h
@@ -313,5 +313,6 @@ int mlx5_flow_destroy(struct rte_eth_dev *, struct rte_flow *,
 int mlx5_flow_flush(struct rte_eth_dev *, struct rte_flow_error *);
 int priv_flow_start(struct priv *);
 void priv_flow_stop(struct priv *);
+int priv_flow_rxq_in_use(struct priv *, struct rxq *);
 
 #endif /* RTE_PMD_MLX5_H_ */
diff --git a/drivers/net/mlx5/mlx5_flow.c b/drivers/net/mlx5/mlx5_flow.c
index c735c438a4..8d62f85e13 100644
--- a/drivers/net/mlx5/mlx5_flow.c
+++ b/drivers/net/mlx5/mlx5_flow.c
@@ -1535,3 +1535,34 @@ priv_flow_start(struct priv *priv)
 	}
 	return 0;
 }
+
+/**
+ * Verify if the Rx queue is used in a flow.
+ *
+ * @param priv
+ *   Pointer to private structure.
+ * @param rxq
+ *   Pointer to the queue to search.
+ *
+ * @return
+ *   Nonzero if the queue is used by a flow.
+ */
+int
+priv_flow_rxq_in_use(struct priv *priv, struct rxq *rxq)
+{
+	struct rte_flow *flow;
+
+	for (flow = LIST_FIRST(&priv->flows);
+	     flow;
+	     flow = LIST_NEXT(flow, next)) {
+		unsigned int n;
+
+		if (flow->drop)
+			continue;
+		for (n = 0; n < flow->rxqs_n; ++n) {
+			if (flow->rxqs[n] == rxq)
+				return 1;
+		}
+	}
+	return 0;
+}
diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
index 556648292e..8b7823360c 100644
--- a/drivers/net/mlx5/mlx5_rxq.c
+++ b/drivers/net/mlx5/mlx5_rxq.c
@@ -59,6 +59,7 @@
 #include <rte_ethdev.h>
 #include <rte_common.h>
 #include <rte_interrupts.h>
+#include <rte_debug.h>
 #ifdef PEDANTIC
 #pragma GCC diagnostic error "-Wpedantic"
 #endif
@@ -1248,6 +1249,9 @@ mlx5_rx_queue_release(void *dpdk_rxq)
 	rxq_ctrl = container_of(rxq, struct rxq_ctrl, rxq);
 	priv = rxq_ctrl->priv;
 	priv_lock(priv);
+	if (priv_flow_rxq_in_use(priv, rxq))
+		rte_panic("Rx queue %p is still used by a flow and cannot be"
+			  " removed\n", (void *)rxq_ctrl);
 	for (i = 0; (i != priv->rxqs_n); ++i)
 		if ((*priv->rxqs)[i] == rxq) {
 			DEBUG("%p: removing RX queue %p from list",
-- 
2.20.1