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

[Stephen Hemminger]

From: Stephen Hemminger <sthem...@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 <sthem...@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