[dpdk-dev] [PATCH] examples/kni: fix crash while handling userspace request

[Ferruh Yigit]

When KNI interface receives RTE_KNI_REQ_CFG_NETWORK_IF request, it
stap/start the physical device which as a result of stop() can free all
the mbufs in its queue.
Meanwhile sample application continues to read from KNI interface queues
and push into device queues. This simultaneous access may cause a crash,
crash log can be found at defect description.

As a solution KNI sample application can do the proper synchronization,
and stop transfer between KNI interface and physical interface while
physical device stop/started.

Bugzilla ID: 116
Fixes: 3fc5ca2f6352 ("kni: initial import")
Cc: stable at dpdk.org

Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
---
Cc: he.qiao17 at zte.com.cn
I am not able to re-produce the defect can you please test with this
patch?

And another concern is performance affect of this patch, new check is
added into fast path. Cc'ed a few more people for comment:
Cc: Igor Ryzhov <iryzhov at nfware.com>
Cc: Phil Yang <phil.yang at arm.com>
Cc: Dan Gora <dg at adax.com>
---
 examples/kni/main.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/examples/kni/main.c b/examples/kni/main.c
index c468ffd19..a8ce07e2a 100644
--- a/examples/kni/main.c
+++ b/examples/kni/main.c
@@ -132,6 +132,7 @@ static int kni_config_network_interface(uint16_t port_id, uint8_t if_up);
 static int kni_config_mac_address(uint16_t port_id, uint8_t mac_addr[]);
 
 static rte_atomic32_t kni_stop = RTE_ATOMIC32_INIT(0);
+static rte_atomic32_t kni_pause = RTE_ATOMIC32_INIT(0);
 
 /* Print out statistics on packets handled */
 static void
@@ -276,6 +277,7 @@ main_loop(__rte_unused void *arg)
 {
 	uint16_t i;
 	int32_t f_stop;
+	int32_t f_pause;
 	const unsigned lcore_id = rte_lcore_id();
 	enum lcore_rxtx {
 		LCORE_NONE,
@@ -304,8 +306,11 @@ main_loop(__rte_unused void *arg)
 					kni_port_params_array[i]->port_id);
 		while (1) {
 			f_stop = rte_atomic32_read(&kni_stop);
+			f_pause = rte_atomic32_read(&kni_pause);
 			if (f_stop)
 				break;
+			if (f_pause)
+				continue;
 			kni_ingress(kni_port_params_array[i]);
 		}
 	} else if (flag == LCORE_TX) {
@@ -314,8 +319,11 @@ main_loop(__rte_unused void *arg)
 					kni_port_params_array[i]->port_id);
 		while (1) {
 			f_stop = rte_atomic32_read(&kni_stop);
+			f_pause = rte_atomic32_read(&kni_pause);
 			if (f_stop)
 				break;
+			if (f_pause)
+				continue;
 			kni_egress(kni_port_params_array[i]);
 		}
 	} else
@@ -807,12 +815,16 @@ kni_config_network_interface(uint16_t port_id, uint8_t if_up)
 	RTE_LOG(INFO, APP, "Configure network interface of %d %s\n",
 					port_id, if_up ? "up" : "down");
 
+	rte_atomic32_inc(&kni_pause);
+
 	if (if_up != 0) { /* Configure network interface up */
 		rte_eth_dev_stop(port_id);
 		ret = rte_eth_dev_start(port_id);
 	} else /* Configure network interface down */
 		rte_eth_dev_stop(port_id);
 
+	rte_atomic32_dec(&kni_pause);
+
 	if (ret < 0)
 		RTE_LOG(ERR, APP, "Failed to start port %d\n", port_id);
 
-- 
2.17.2