[dpdk-stable] [DPDK] bus/ifpga: fix ifpga afu driver probe failure handler

[Andy Pei <andy.pei@intel.com>]

From: AndyPei <andy.pei@intel.com>

In the original code, when an AFU device probe a driver,
if the first driver in the driver list does not support
this device or some error happens, an error is returned.
With this patch, a device wil try to match driver
in the driver list one by one until an appropriate
driver is found. If some error happens, the error is 
returned. If the current driver does not support the 
device, just try the next driver in the list.
If all the drivers in the list are tried and no
driver matches, 0 is returned. Otherwise, the error code 
is returned.

Fixes: 05fa3d4a6539 ("bus/ifpga: add Intel FPGA bus library")
Cc: stable@dpdk.org

Signed-off-by: AndyPei <andy.pei@intel.com>
---
 drivers/bus/ifpga/ifpga_bus.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/bus/ifpga/ifpga_bus.c b/drivers/bus/ifpga/ifpga_bus.c
index e4b7b6f..55d3abf 100644
--- a/drivers/bus/ifpga/ifpga_bus.c
+++ b/drivers/bus/ifpga/ifpga_bus.c
@@ -306,12 +306,19 @@ void rte_ifpga_driver_unregister(struct rte_afu_driver *driver)
 	}
 
 	TAILQ_FOREACH(drv, &ifpga_afu_drv_list, next) {
-		if (ifpga_probe_one_driver(drv, afu_dev)) {
-			ret = -1;
-			break;
-		}
+		ret = ifpga_probe_one_driver(drv, afu_dev);
+		if (ret < 0)
+			/* negative value is an error */
+			return ret;
+		if (ret > 0)
+			/* positive value means driver doesn't support it */
+			continue;
+		return 0;
 	}
-	return ret;
+	if ((ret > 0) && (afu_dev->driver == NULL))
+		return 0;
+	else
+		return ret;
 }
 
 /*
-- 
1.8.3.1