Merge branch 'Build BPF selftests and its libbpf, bpftool in debug mode'

Andrii Nakryiko says:

====================

Build BPF selftests and libbpf and bpftool, that are used as part of
selftests, in debug mode (specifically, -Og). This makes it much simpler and
nicer to do development and/or bug fixing. See patch #4 for some unscientific
measurements.

This patch set fixes new maybe-unitialized warnings produced in -Og build
mode. Patch #1 fixes the blocker which was causing some XDP selftests failures
due to non-zero padding in bpf_xdp_set_link_opts, which only happened in debug
mode.
====================

Signed-off-by: Alexei Starovoitov <[e-mail]>

tools/bpf/bpftool/btf.c

···
 			NEXT_ARG();
 			if (argc < 1) {
 				p_err("expecting value for 'format' option\n");
+				err = -EINVAL;
 				goto done;
 			}
 			if (strcmp(*argv, "c") == 0) {
···
 			} else {
 				p_err("unrecognized format specifier: '%s', possible values: raw, c",
 				      *argv);
+				err = -EINVAL;
 				goto done;
 			}
 			NEXT_ARG();
 		} else {
 			p_err("unrecognized option: '%s'", *argv);
+			err = -EINVAL;
 			goto done;
 		}
 	}

tools/bpf/bpftool/main.c

···
 	int n_argc;
 	FILE *fp;
 	char *cp;
-	int err;
+	int err = 0;
 	int i;
 
 	if (argc < 2) {
···
 	} else {
 		if (!json_output)
 			printf("processed %d commands\n", lines);
-		err = 0;
 	}
 err_close:
 	if (fp != stdin)

tools/bpf/bpftool/map.c

···
 		       void *value)
 {
 	__u32 value_id;
-	int ret;
+	int ret = 0;
 
 	/* start of key-value pair */
 	jsonw_start_object(d->jw);

tools/lib/bpf/libbpf.h

···
 struct bpf_xdp_set_link_opts {
 	size_t sz;
 	int old_fd;
+	size_t :0;
 };
 #define bpf_xdp_set_link_opts__last_field old_fd
 

tools/testing/selftests/bpf/Makefile

···
 
 BPF_GCC		?= $(shell command -v bpf-gcc;)
 SAN_CFLAGS	?=
-CFLAGS += -g -rdynamic -Wall -O2 $(GENFLAGS) $(SAN_CFLAGS)		\
+CFLAGS += -g -Og -rdynamic -Wall $(GENFLAGS) $(SAN_CFLAGS)		\
 	  -I$(CURDIR) -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR)		\
 	  -I$(TOOLSINCDIR) -I$(APIDIR) -I$(OUTPUT)			\
 	  -Dbpf_prog_load=bpf_prog_test_load				\
···
 		    $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/bpftool
 	$(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)			       \
 		    CC=$(HOSTCC) LD=$(HOSTLD)				       \
+		    EXTRA_CFLAGS='-g -Og'				       \
 		    OUTPUT=$(HOST_BUILD_DIR)/bpftool/			       \
 		    prefix= DESTDIR=$(HOST_SCRATCH_DIR)/ install
 
···
 	   ../../../include/uapi/linux/bpf.h                                   \
 	   | $(INCLUDE_DIR) $(BUILD_DIR)/libbpf
 	$(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/ \
+		    EXTRA_CFLAGS='-g -Og'					       \
 		    DESTDIR=$(SCRATCH_DIR) prefix= all install_headers
 
 ifneq ($(BPFOBJ),$(HOST_BPFOBJ))
···
 	   ../../../include/uapi/linux/bpf.h                                   \
 	   | $(INCLUDE_DIR) $(HOST_BUILD_DIR)/libbpf
 	$(Q)$(MAKE) $(submake_extras) -C $(BPFDIR)                             \
-		OUTPUT=$(HOST_BUILD_DIR)/libbpf/ CC=$(HOSTCC) LD=$(HOSTLD)     \
+		    EXTRA_CFLAGS='-g -Og'					       \
+		    OUTPUT=$(HOST_BUILD_DIR)/libbpf/ CC=$(HOSTCC) LD=$(HOSTLD) \
 		    DESTDIR=$(HOST_SCRATCH_DIR)/ prefix= all install_headers
 endif
 

tools/testing/selftests/bpf/xdpxceiver.c

···
 static void xsk_populate_fill_ring(struct xsk_umem_info *umem)
 {
 	int ret, i;
-	u32 idx;
+	u32 idx = 0;
 
 	ret = xsk_ring_prod__reserve(&umem->fq, XSK_RING_PROD__DEFAULT_NUM_DESCS, &idx);
 	if (ret != XSK_RING_PROD__DEFAULT_NUM_DESCS)
···
 
 static void tx_only(struct xsk_socket_info *xsk, u32 *frameptr, int batch_size)
 {
-	u32 idx;
+	u32 idx = 0;
 	unsigned int i;
 	bool tx_invalid_test = stat_test_type == STAT_TEST_TX_INVALID;
 	u32 len = tx_invalid_test ? XSK_UMEM__DEFAULT_FRAME_SIZE + 1 : PKT_SIZE;