ethdev: fix potential leak in PCI probing helper

Sanity check is performed after a rte_eth_dev object is allocated.

The object is not freed if the check fails, though in the current
reality this never happens, but it's better programming paradigm
to move the quick check up front to the start of
rte_eth_dev_pci_generic_probe().

Fixes: dcd5c81 ("ethdev: add PCI driver helpers")
Cc: stable@dpdk.org

Signed-off-by: Kaiyu Zhang <squirrel.prog@gmail.com>
Reviewed-by: Chengwen Feng <fengchengwen@huawei.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@amd.com>

.mailmap

@@ -698,6 +698,7 @@ Kai Ji <kai.ji@intel.com>
 Kaijun Zeng <corezeng@gmail.com>
 Kaisen You <kaisenx.you@intel.com>
 Kaiwen Deng <kaiwenx.deng@intel.com>
+Kaiyu Zhang <squirrel.prog@gmail.com>
 Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
 Kamalakannan R <kamalakannan.r@intel.com>
 Kamalakshitha Aligeri <kamalakshitha.aligeri@arm.com>

lib/ethdev/ethdev_pci.h

@@ -126,12 +126,13 @@ rte_eth_dev_pci_generic_probe(struct rte_pci_device *pci_dev,
 	struct rte_eth_dev *eth_dev;
 	int ret;
 
+	if (*dev_init == NULL)
+		return -EINVAL;
+
 	eth_dev = rte_eth_dev_pci_allocate(pci_dev, private_data_size);
 	if (!eth_dev)
 		return -ENOMEM;
 
-	if (*dev_init == NULL)
-		return -EINVAL;
 	ret = dev_init(eth_dev);
 	if (ret)
 		rte_eth_dev_release_port(eth_dev);