[PATCH bpf] selftests/bpf/test_progs: do not check errno == 0

[PATCH bpf] selftests/bpf/test_progs: do not check errno == 0

[Mauricio Vasquez B]

The errno man page states: "The value in errno is significant only when
the return value of the call indicated an error..." then it is not correct
to check it, it could be different than zero even if the function
succeeded.

It causes some false positives if errno is set by a previous function.

Signed-off-by: Mauricio Vasquez B <mauricio.vasquez@polito.it>
---
 tools/testing/selftests/bpf/test_progs.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 0ef68204c84b..63a671803ed6 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -112,13 +112,13 @@ static void test_pkt_access(void)
 
 	err = bpf_prog_test_run(prog_fd, 100000, &pkt_v4, sizeof(pkt_v4),
 				NULL, NULL, &retval, &duration);
-	CHECK(err || errno || retval, "ipv4",
+	CHECK(err || retval, "ipv4",
 	      "err %d errno %d retval %d duration %d\n",
 	      err, errno, retval, duration);
 
 	err = bpf_prog_test_run(prog_fd, 100000, &pkt_v6, sizeof(pkt_v6),
 				NULL, NULL, &retval, &duration);
-	CHECK(err || errno || retval, "ipv6",
+	CHECK(err || retval, "ipv6",
 	      "err %d errno %d retval %d duration %d\n",
 	      err, errno, retval, duration);
 	bpf_object__close(obj);
@@ -153,14 +153,14 @@ static void test_xdp(void)
 	err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4),
 				buf, &size, &retval, &duration);
 
-	CHECK(err || errno || retval != XDP_TX || size != 74 ||
+	CHECK(err || retval != XDP_TX || size != 74 ||
 	      iph->protocol != IPPROTO_IPIP, "ipv4",
 	      "err %d errno %d retval %d size %d\n",
 	      err, errno, retval, size);
 
 	err = bpf_prog_test_run(prog_fd, 1, &pkt_v6, sizeof(pkt_v6),
 				buf, &size, &retval, &duration);
-	CHECK(err || errno || retval != XDP_TX || size != 114 ||
+	CHECK(err || retval != XDP_TX || size != 114 ||
 	      iph6->nexthdr != IPPROTO_IPV6, "ipv6",
 	      "err %d errno %d retval %d size %d\n",
 	      err, errno, retval, size);
@@ -185,13 +185,13 @@ static void test_xdp_adjust_tail(void)
 	err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4),
 				buf, &size, &retval, &duration);
 
-	CHECK(err || errno || retval != XDP_DROP,
+	CHECK(err || retval != XDP_DROP,
 	      "ipv4", "err %d errno %d retval %d size %d\n",
 	      err, errno, retval, size);
 
 	err = bpf_prog_test_run(prog_fd, 1, &pkt_v6, sizeof(pkt_v6),
 				buf, &size, &retval, &duration);
-	CHECK(err || errno || retval != XDP_TX || size != 54,
+	CHECK(err || retval != XDP_TX || size != 54,
 	      "ipv6", "err %d errno %d retval %d size %d\n",
 	      err, errno, retval, size);
 	bpf_object__close(obj);
@@ -254,14 +254,14 @@ static void test_l4lb(const char *file)
 
 	err = bpf_prog_test_run(prog_fd, NUM_ITER, &pkt_v4, sizeof(pkt_v4),
 				buf, &size, &retval, &duration);
-	CHECK(err || errno || retval != 7/*TC_ACT_REDIRECT*/ || size != 54 ||
+	CHECK(err || retval != 7/*TC_ACT_REDIRECT*/ || size != 54 ||
 	      *magic != MAGIC_VAL, "ipv4",
 	      "err %d errno %d retval %d size %d magic %x\n",
 	      err, errno, retval, size, *magic);
 
 	err = bpf_prog_test_run(prog_fd, NUM_ITER, &pkt_v6, sizeof(pkt_v6),
 				buf, &size, &retval, &duration);
-	CHECK(err || errno || retval != 7/*TC_ACT_REDIRECT*/ || size != 74 ||
+	CHECK(err || retval != 7/*TC_ACT_REDIRECT*/ || size != 74 ||
 	      *magic != MAGIC_VAL, "ipv6",
 	      "err %d errno %d retval %d size %d magic %x\n",
 	      err, errno, retval, size, *magic);
@@ -343,14 +343,14 @@ static void test_xdp_noinline(void)
 
 	err = bpf_prog_test_run(prog_fd, NUM_ITER, &pkt_v4, sizeof(pkt_v4),
 				buf, &size, &retval, &duration);
-	CHECK(err || errno || retval != 1 || size != 54 ||
+	CHECK(err || retval != 1 || size != 54 ||
 	      *magic != MAGIC_VAL, "ipv4",
 	      "err %d errno %d retval %d size %d magic %x\n",
 	      err, errno, retval, size, *magic);
 
 	err = bpf_prog_test_run(prog_fd, NUM_ITER, &pkt_v6, sizeof(pkt_v6),
 				buf, &size, &retval, &duration);
-	CHECK(err || errno || retval != 1 || size != 74 ||
+	CHECK(err || retval != 1 || size != 74 ||
 	      *magic != MAGIC_VAL, "ipv6",
 	      "err %d errno %d retval %d size %d magic %x\n",
 	      err, errno, retval, size, *magic);
-- 
2.7.4

Re: [PATCH bpf] selftests/bpf/test_progs: do not check errno == 0

[Alexei Starovoitov]

On Mon, Sep 03, 2018 at 07:01:59PM +0200, Mauricio Vasquez B wrote:
> The errno man page states: "The value in errno is significant only when
> the return value of the call indicated an error..." then it is not correct
> to check it, it could be different than zero even if the function
> succeeded.
> 
> It causes some false positives if errno is set by a previous function.
> 
> Signed-off-by: Mauricio Vasquez B <mauricio.vasquez@polito.it>

Applied, Thanks