[PATCH 5.1 36/62] selftests: txring_overwrite: fix incorrect test of mmap() return value

[Greg Kroah-Hartman]

From: Frank de Brabander <debraban...@gmail.com>

[ Upstream commit cecaa76b2919aac2aa584ce476e9fcd5b084add5 ]

If mmap() fails it returns MAP_FAILED, which is defined as ((void *) -1).
The current if-statement incorrectly tests if *ring is NULL.

Fixes: 358be656406d ("selftests/net: add txring_overwrite")
Signed-off-by: Frank de Brabander <debraban...@gmail.com>
Acked-by: Willem de Bruijn <will...@google.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 tools/testing/selftests/net/txring_overwrite.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/testing/selftests/net/txring_overwrite.c
+++ b/tools/testing/selftests/net/txring_overwrite.c
@@ -113,7 +113,7 @@ static int setup_tx(char **ring)
 
        *ring = mmap(0, req.tp_block_size * req.tp_block_nr,
                     PROT_READ | PROT_WRITE, MAP_SHARED, fdt, 0);
-       if (!*ring)
+       if (*ring == MAP_FAILED)
                error(1, errno, "mmap");
 
        return fdt;