[dpdk-dev] [PATCH 3/7] bus/vmbus: fix check for mmap failure

[Stephen Hemminger <stephen@networkplumber.org>]

From: Stephen Hemminger <sthemmin@microsoft.com>

The code was testing the result of mmap incorrectly.
I.e the test that a local pointer is not MAP_FAILED would
always succeed and therefore hid any potential problems.

Fixes: 831dba47bd36 ("bus/vmbus: add Hyper-V virtual bus support")
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
---
 drivers/bus/vmbus/linux/vmbus_uio.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/bus/vmbus/linux/vmbus_uio.c b/drivers/bus/vmbus/linux/vmbus_uio.c
index 09f7efdca286..8c6bc52fd475 100644
--- a/drivers/bus/vmbus/linux/vmbus_uio.c
+++ b/drivers/bus/vmbus/linux/vmbus_uio.c
@@ -202,6 +202,7 @@ static int vmbus_uio_map_subchan(const struct rte_vmbus_device *dev,
 	char ring_path[PATH_MAX];
 	size_t file_size;
 	struct stat sb;
+	void *mapaddr;
 	int fd;
 
 	snprintf(ring_path, sizeof(ring_path),
@@ -232,14 +233,16 @@ static int vmbus_uio_map_subchan(const struct rte_vmbus_device *dev,
 		return -EINVAL;
 	}
 
-	*ring_size = file_size / 2;
-	*ring_buf = vmbus_map_resource(vmbus_map_addr, fd,
-				       0, sb.st_size, 0);
+	mapaddr = vmbus_map_resource(vmbus_map_addr, fd,
+				     0, file_size, 0);
 	close(fd);
 
-	if (ring_buf == MAP_FAILED)
+	if (mapaddr == MAP_FAILED)
 		return -EIO;
 
+	*ring_size = file_size / 2;
+	*ring_buf = mapaddr;
+
 	vmbus_map_addr = RTE_PTR_ADD(ring_buf, file_size);
 	return 0;
 }
-- 
2.20.1