rtla: Add libsubcmd dependency

In preparation for migrating RTLA to libsubcmd, build libsubcmd from the
appropriate directory next to the RTLA build proper, and link the
resulting object to RTLA.

libsubcmd uses str_error_r() and strlcpy() at several places. To support
these, also link the respective libraries from tools/lib.

For completeness, also add tools/include to include path. This will
allow other userspace functions and macros shipped with the kernel to be
used in RTLA; perf and bpftool, two other users of libsubcmd, already do
that.

To prevent a name conflict, rename RTLA's run_command() function to
run_tool_command(), and replace RTLA's own container_of implementation
with the one in tools/include/linux/container_of.h.

Assisted-by: Composer:composer-1
Link: https://lore.kernel.org/r/20260528103254.2990068-2-tglozar@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>

Author: lenticularis39

tools/tracing/rtla/.gitignore

@@ -10,3 +10,5 @@ custom_filename.txt
 osnoise_irq_noise_hist.txt
 osnoise_trace.txt
 timerlat_trace.txt
+libsubcmd/
+lib/

tools/tracing/rtla/Makefile

@@ -27,6 +27,30 @@ endif
 RTLA		:= $(OUTPUT)rtla
 RTLA_IN		:= $(RTLA)-in.o
 
+LIBSUBCMD_DIR = $(srctree)/tools/lib/subcmd/
+ifneq ($(OUTPUT),)
+  LIBSUBCMD_OUTPUT = $(abspath $(OUTPUT))/libsubcmd
+else
+  LIBSUBCMD_OUTPUT = $(CURDIR)/libsubcmd
+endif
+LIBSUBCMD = $(LIBSUBCMD_OUTPUT)/libsubcmd.a
+LIBSUBCMD_INCLUDES = $(LIBSUBCMD_OUTPUT)/include
+LIBSUBCMD_MAKEFLAGS = O=$(LIBSUBCMD_OUTPUT) DESTDIR=$(LIBSUBCMD_OUTPUT) prefix= subdir=
+
+TOOLS_INCLUDES = -I$(srctree)/tools/include
+
+ifneq ($(OUTPUT),)
+  LIB_OUTPUT = $(abspath $(OUTPUT))/lib
+else
+  LIB_OUTPUT = $(CURDIR)/lib
+endif
+
+LIB_STRING = $(LIB_OUTPUT)/string.o
+LIB_STRING_SRC = $(srctree)/tools/lib/string.c
+
+LIB_STR_ERROR_R = $(LIB_OUTPUT)/str_error_r.o
+LIB_STR_ERROR_R_SRC = $(srctree)/tools/lib/str_error_r.c
+
 VERSION		:= $(shell sh -c "make -sC ../../.. kernelversion | grep -v make")
 DOCSRC		:= ../../../Documentation/tools/rtla/
 
@@ -66,7 +90,7 @@ ifeq ($(config),1)
   include Makefile.config
 endif
 
-CFLAGS		+= $(INCLUDES) $(LIB_INCLUDES)
+CFLAGS		+= $(INCLUDES) $(LIB_INCLUDES) $(TOOLS_INCLUDES) -I$(LIBSUBCMD_INCLUDES)
 
 export CFLAGS OUTPUT srctree
 
@@ -93,20 +117,48 @@ tests/bpf/bpf_action_map.o: tests/bpf/bpf_action_map.c
 	$(Q)echo "BPF skeleton support is disabled, skipping tests/bpf/bpf_action_map.o"
 endif
 
-$(RTLA): $(RTLA_IN)
-	$(QUIET_LINK)$(CC) $(LDFLAGS) -o $(RTLA) $(RTLA_IN) $(EXTLIBS)
+$(RTLA): $(RTLA_IN) $(LIBSUBCMD) $(LIB_STRING) $(LIB_STR_ERROR_R)
+	$(QUIET_LINK)$(CC) $(LDFLAGS) -o $(RTLA) $(RTLA_IN) $(LIBSUBCMD) $(LIB_STRING) $(LIB_STR_ERROR_R) $(EXTLIBS)
 
-static: $(RTLA_IN)
+static: $(RTLA_IN) $(LIBSUBCMD) $(LIB_STRING) $(LIB_STR_ERROR_R)
 	$(eval LDFLAGS += -static)
-	$(QUIET_LINK)$(CC) -static $(LDFLAGS) -o $(RTLA)-static $(RTLA_IN)  $(EXTLIBS)
+	$(QUIET_LINK)$(CC) -static $(LDFLAGS) -o $(RTLA)-static $(RTLA_IN) $(LIBSUBCMD) $(LIB_STRING) $(LIB_STR_ERROR_R) $(EXTLIBS)
 
 rtla.%: fixdep FORCE
 	make -f $(srctree)/tools/build/Makefile.build dir=. $@
 
-$(RTLA_IN): fixdep FORCE src/timerlat.skel.h
+$(RTLA_IN): fixdep FORCE src/timerlat.skel.h $(LIBSUBCMD_INCLUDES)
 	make $(build)=rtla
 
-clean: doc_clean fixdep-clean
+$(LIBSUBCMD_OUTPUT):
+	$(Q)$(MKDIR) -p $@
+
+$(LIBSUBCMD_INCLUDES): FORCE | $(LIBSUBCMD_OUTPUT)
+	$(Q)$(MAKE) -C $(LIBSUBCMD_DIR) $(LIBSUBCMD_MAKEFLAGS) \
+		install_headers
+
+$(LIBSUBCMD): FORCE | $(LIBSUBCMD_OUTPUT)
+	$(Q)$(MAKE) -C $(LIBSUBCMD_DIR) $(LIBSUBCMD_MAKEFLAGS) \
+		$@
+
+$(LIB_OUTPUT):
+	$(Q)$(MKDIR) -p $@
+
+$(LIB_STR_ERROR_R): $(LIB_STR_ERROR_R_SRC) | $(LIB_OUTPUT)
+	$(QUIET_CC)$(CC) $(CFLAGS) -c -o $@ $<
+
+$(LIB_STRING): $(LIB_STRING_SRC) | $(LIB_OUTPUT)
+	$(QUIET_CC)$(CC) $(CFLAGS) -c -o $@ $<
+
+libsubcmd-clean:
+	$(call QUIET_CLEAN, libsubcmd)
+	$(Q)$(RM) -r -- $(LIBSUBCMD_OUTPUT)
+
+lib-clean:
+	$(call QUIET_CLEAN, lib)
+	$(Q)$(RM) -r -- $(LIB_OUTPUT)
+
+clean: doc_clean fixdep-clean libsubcmd-clean lib-clean
 	$(call QUIET_CLEAN, rtla)
 	$(Q)find . -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
 	$(Q)rm -f rtla rtla-static fixdep FEATURE-DUMP rtla-*

tools/tracing/rtla/src/rtla.c

@@ -38,12 +38,12 @@ static void rtla_usage(int err)
 }
 
 /*
- * run_command - try to run a rtla tool command
+ * run_tool_command - try to run a rtla tool command
  *
  * It returns 0 if it fails. The tool's main will generally not
  * return as they should call exit().
  */
-int run_command(int argc, char **argv, int start_position)
+int run_tool_command(int argc, char **argv, int start_position)
 {
 	if (strcmp(argv[start_position], "osnoise") == 0) {
 		osnoise_main(argc-start_position, &argv[start_position]);
@@ -69,7 +69,7 @@ int main(int argc, char *argv[])
 	int retval;
 
 	/* is it an alias? */
-	retval = run_command(argc, argv, 0);
+	retval = run_tool_command(argc, argv, 0);
 	if (retval)
 		exit(0);
 
@@ -82,7 +82,7 @@ int main(int argc, char *argv[])
 		rtla_usage(0);
 	}
 
-	retval = run_command(argc, argv, 1);
+	retval = run_tool_command(argc, argv, 1);
 	if (retval)
 		exit(0);
 

tools/tracing/rtla/src/utils.h

@@ -7,6 +7,8 @@
 #include <stdbool.h>
 #include <stdlib.h>
 
+#include <linux/container_of.h>
+
 /*
  * '18446744073709551615\0'
  */
@@ -37,10 +39,6 @@ static inline bool str_has_prefix(const char *str, const char *prefix)
 	return strncmp(str, prefix, strlen(prefix)) == 0;
 }
 
-#define container_of(ptr, type, member)({			\
-	const typeof(((type *)0)->member) *__mptr = (ptr);	\
-	(type *)((char *)__mptr - offsetof(type, member)) ; })
-
 extern int config_debug;
 void debug_msg(const char *fmt, ...);
 void err_msg(const char *fmt, ...);