Subject: [PATCH 39/49] selftests: txring_overwrite: fix incorrect test of mmap() return value

From: Frank de Brabander <[email-masked]>
Date: Fri, 5 Jul 2019 13:43:14 +0200

[ 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 <[email-masked]>
Acked-by: Willem de Bruijn <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 tools/testing/selftests/net/txring_overwrite.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/txring_overwrite.c b/tools/testing/selftests/net/txring_overwrite.c
index fd8b1c663c39..7d9ea039450a 100644
--- 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;
-- 
2.20.1