selftests/bpf/test_progs: do not check errno == 0

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>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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);