If the value _SC_IOV_MAX is missing, sysconf returns -1.
In this case, iov_max is set to a default value of 1024.

Cc: sta...@dpdk.org

Signed-off-by: Oleg Polyakov <olegp...@walla.co.il>
---
 drivers/net/tap/rte_eth_tap.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
index 6f5109fca..2a7e6aa00 100644
--- a/drivers/net/tap/rte_eth_tap.c
+++ b/drivers/net/tap/rte_eth_tap.c
@@ -68,6 +68,8 @@
 /* IPC key for queue fds sync */
 #define TAP_MP_KEY "tap_mp_sync_queues"
 
+#define TAP_IOV_DEFAULT_MAX 1024
+
 static int tap_devices_count;
 static struct rte_vdev_driver pmd_tap_drv;
 static struct rte_vdev_driver pmd_tun_drv;
@@ -1326,6 +1328,12 @@ tap_rx_queue_setup(struct rte_eth_dev *dev,
        struct rx_queue *rxq = &internals->rxq[rx_queue_id];
        struct rte_mbuf **tmp = &rxq->pool;
        long iov_max = sysconf(_SC_IOV_MAX);
+
+       if (iov_max <= 0) {
+               TAP_LOG(WARNING,
+                       "_SC_IOV_MAX is not defined. Using %d as default\n", 
TAP_IOV_DEFAULT_MAX);
+               iov_max = TAP_IOV_DEFAULT_MAX;
+       }
        uint16_t nb_desc = RTE_MIN(nb_rx_desc, iov_max - 1);
        struct iovec (*iovecs)[nb_desc + 1];
        int data_off = RTE_PKTMBUF_HEADROOM;
-- 
2.14.1

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