Updates to Real Time Linux Analysis tool for 5.19:

Various clean ups and fixes.
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Merge tag 'trace-tools-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing tool updates from Steven Rostedt:

 - Various clean ups and fixes to rtla (Real Time Linux Analysis)

* tag 'trace-tools-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  rtla: Remove procps-ng dependency
  rtla: Fix __set_sched_attr error message
  rtla: Minor grammar fix for rtla README
  rtla: Don't overwrite existing directory mode
  rtla: Avoid record NULL pointer dereference
  rtla/Makefile: Properly handle dependencies

Documentation/tools/rtla/Makefile

@@ -17,9 +17,21 @@ DOC_MAN1	= $(addprefix $(OUTPUT),$(_DOC_MAN1))
 RST2MAN_DEP	:= $(shell command -v rst2man 2>/dev/null)
 RST2MAN_OPTS	+= --verbose
 
+TEST_RST2MAN = $(shell sh -c "rst2man --version > /dev/null 2>&1 || echo n")
+
 $(OUTPUT)%.1: %.rst
 ifndef RST2MAN_DEP
-	$(error "rst2man not found, but required to generate man pages")
+	$(info ********************************************)
+	$(info ** NOTICE: rst2man not found)
+	$(info **)
+	$(info ** Consider installing the latest rst2man from your)
+	$(info ** distribution, e.g., 'dnf install python3-docutils' on Fedora,)
+	$(info ** or from source:)
+	$(info **)
+	$(info **  https://docutils.sourceforge.io/docs/dev/repository.html )
+	$(info **)
+	$(info ********************************************)
+	$(error NOTICE: rst2man required to generate man pages)
 endif
 	rst2man $(RST2MAN_OPTS) $< > $@
 

tools/tracing/rtla/Makefile

@@ -23,6 +23,7 @@ $(call allow-override,LD_SO_CONF_PATH,/etc/ld.so.conf.d/)
 $(call allow-override,LDCONFIG,ldconfig)
 
 INSTALL	=	install
+MKDIR	=	mkdir
 FOPTS	:=	-flto=auto -ffat-lto-objects -fexceptions -fstack-protector-strong \
 		-fasynchronous-unwind-tables -fstack-clash-protection
 WOPTS	:= 	-Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -Wno-maybe-uninitialized
@@ -31,7 +32,7 @@ TRACEFS_HEADERS	:= $$($(PKG_CONFIG) --cflags libtracefs)
 
 CFLAGS	:=	-O -g -DVERSION=\"$(VERSION)\" $(FOPTS) $(MOPTS) $(WOPTS) $(TRACEFS_HEADERS)
 LDFLAGS	:=	-ggdb
-LIBS	:=	$$($(PKG_CONFIG) --libs libtracefs) -lprocps
+LIBS	:=	$$($(PKG_CONFIG) --libs libtracefs)
 
 SRC	:=	$(wildcard src/*.c)
 HDR	:=	$(wildcard src/*.h)
@@ -57,6 +58,41 @@ else
 DOCSRC	=	$(SRCTREE)/../../../Documentation/tools/rtla/
 endif
 
+LIBTRACEEVENT_MIN_VERSION = 1.5
+LIBTRACEFS_MIN_VERSION = 1.3
+
+TEST_LIBTRACEEVENT = $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEEVENT_MIN_VERSION) libtraceevent > /dev/null 2>&1 || echo n")
+ifeq ("$(TEST_LIBTRACEEVENT)", "n")
+.PHONY: warning_traceevent
+warning_traceevent:
+	@echo "********************************************"
+	@echo "** NOTICE: libtraceevent version $(LIBTRACEEVENT_MIN_VERSION) or higher not found"
+	@echo "**"
+	@echo "** Consider installing the latest libtraceevent from your"
+	@echo "** distribution, e.g., 'dnf install libtraceevent' on Fedora,"
+	@echo "** or from source:"
+	@echo "**"
+	@echo "**  https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/ "
+	@echo "**"
+	@echo "********************************************"
+endif
+
+TEST_LIBTRACEFS = $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEFS_MIN_VERSION) libtracefs > /dev/null 2>&1 || echo n")
+ifeq ("$(TEST_LIBTRACEFS)", "n")
+.PHONY: warning_tracefs
+warning_tracefs:
+	@echo "********************************************"
+	@echo "** NOTICE: libtracefs version $(LIBTRACEFS_MIN_VERSION) or higher not found"
+	@echo "**"
+	@echo "** Consider installing the latest libtracefs from your"
+	@echo "** distribution, e.g., 'dnf install libtracefs' on Fedora,"
+	@echo "** or from source:"
+	@echo "**"
+	@echo "**  https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ "
+	@echo "**"
+	@echo "********************************************"
+endif
+
 .PHONY:	all
 all:	rtla
 
@@ -68,7 +104,7 @@ static: $(OBJ)
 
 .PHONY: install
 install: doc_install
-	$(INSTALL) -d -m 755 $(DESTDIR)$(BINDIR)
+	$(MKDIR) -p $(DESTDIR)$(BINDIR)
 	$(INSTALL) rtla -m 755 $(DESTDIR)$(BINDIR)
 	$(STRIP) $(DESTDIR)$(BINDIR)/rtla
 	@test ! -f $(DESTDIR)$(BINDIR)/osnoise || rm $(DESTDIR)$(BINDIR)/osnoise

tools/tracing/rtla/README.txt

@@ -1,19 +1,16 @@
 RTLA: Real-Time Linux Analysis tools
 
-The rtla is a meta-tool that includes a set of commands that
+The rtla meta-tool includes a set of commands that aims to analyze
-aims to analyze the real-time properties of Linux. But, instead of
+the real-time properties of Linux. Instead of testing Linux as a black box,
-testing Linux as a black box, rtla leverages kernel tracing
+rtla leverages kernel tracing capabilities to provide precise information
-capabilities to provide precise information about the properties
+about the properties and root causes of unexpected results.
-and root causes of unexpected results.
 
 Installing RTLA
 
-RTLA depends on some libraries and tools. More precisely, it depends on the
+RTLA depends on the following libraries and tools:
-following libraries:
 
  - libtracefs
  - libtraceevent
- - procps
 
 It also depends on python3-docutils to compile man pages.
 

tools/tracing/rtla/src/osnoise_hist.c

@@ -809,7 +809,7 @@ int osnoise_hist_main(int argc, char *argv[])
 		retval = set_comm_sched_attr("osnoise/", &params->sched_param);
 		if (retval) {
 			err_msg("Failed to set sched parameters\n");
-			goto out_hist;
+			goto out_free;
 		}
 	}
 
@@ -819,7 +819,7 @@ int osnoise_hist_main(int argc, char *argv[])
 		record = osnoise_init_trace_tool("osnoise");
 		if (!record) {
 			err_msg("Failed to enable the trace instance\n");
-			goto out_hist;
+			goto out_free;
 		}
 
 		if (params->events) {
@@ -869,6 +869,7 @@ int osnoise_hist_main(int argc, char *argv[])
 out_hist:
 	trace_events_destroy(&record->trace, params->events);
 	params->events = NULL;
+out_free:
 	osnoise_free_histogram(tool->data);
 out_destroy:
 	osnoise_destroy_tool(record);

tools/tracing/rtla/src/osnoise_top.c

@@ -572,7 +572,7 @@ int osnoise_top_main(int argc, char **argv)
 	retval = osnoise_top_apply_config(tool, params);
 	if (retval) {
 		err_msg("Could not apply config\n");
-		goto out_top;
+		goto out_free;
 	}
 
 	trace = &tool->trace;
@@ -580,14 +580,14 @@ int osnoise_top_main(int argc, char **argv)
 	retval = enable_osnoise(trace);
 	if (retval) {
 		err_msg("Failed to enable osnoise tracer\n");
-		goto out_top;
+		goto out_free;
 	}
 
 	if (params->set_sched) {
 		retval = set_comm_sched_attr("osnoise/", &params->sched_param);
 		if (retval) {
 			err_msg("Failed to set sched parameters\n");
-			goto out_top;
+			goto out_free;
 		}
 	}
 
@@ -597,7 +597,7 @@ int osnoise_top_main(int argc, char **argv)
 		record = osnoise_init_trace_tool("osnoise");
 		if (!record) {
 			err_msg("Failed to enable the trace instance\n");
-			goto out_top;
+			goto out_free;
 		}
 
 		if (params->events) {
@@ -649,6 +649,7 @@ int osnoise_top_main(int argc, char **argv)
 out_top:
 	trace_events_destroy(&record->trace, params->events);
 	params->events = NULL;
+out_free:
 	osnoise_free_top(tool->data);
 	osnoise_destroy_tool(record);
 	osnoise_destroy_tool(tool);

tools/tracing/rtla/src/timerlat_hist.c

@@ -821,7 +821,7 @@ int timerlat_hist_main(int argc, char *argv[])
 	retval = timerlat_hist_apply_config(tool, params);
 	if (retval) {
 		err_msg("Could not apply config\n");
-		goto out_hist;
+		goto out_free;
 	}
 
 	trace = &tool->trace;
@@ -829,14 +829,14 @@ int timerlat_hist_main(int argc, char *argv[])
 	retval = enable_timerlat(trace);
 	if (retval) {
 		err_msg("Failed to enable timerlat tracer\n");
-		goto out_hist;
+		goto out_free;
 	}
 
 	if (params->set_sched) {
 		retval = set_comm_sched_attr("timerlat/", &params->sched_param);
 		if (retval) {
 			err_msg("Failed to set sched parameters\n");
-			goto out_hist;
+			goto out_free;
 		}
 	}
 
@@ -844,7 +844,7 @@ int timerlat_hist_main(int argc, char *argv[])
 		dma_latency_fd = set_cpu_dma_latency(params->dma_latency);
 		if (dma_latency_fd < 0) {
 			err_msg("Could not set /dev/cpu_dma_latency.\n");
-			goto out_hist;
+			goto out_free;
 		}
 	}
 
@@ -854,7 +854,7 @@ int timerlat_hist_main(int argc, char *argv[])
 		record = osnoise_init_trace_tool("timerlat");
 		if (!record) {
 			err_msg("Failed to enable the trace instance\n");
-			goto out_hist;
+			goto out_free;
 		}
 
 		if (params->events) {
@@ -904,6 +904,7 @@ out_hist:
 		close(dma_latency_fd);
 	trace_events_destroy(&record->trace, params->events);
 	params->events = NULL;
+out_free:
 	timerlat_free_histogram(tool->data);
 	osnoise_destroy_tool(record);
 	osnoise_destroy_tool(tool);

tools/tracing/rtla/src/timerlat_top.c

@@ -612,7 +612,7 @@ int timerlat_top_main(int argc, char *argv[])
 	retval = timerlat_top_apply_config(top, params);
 	if (retval) {
 		err_msg("Could not apply config\n");
-		goto out_top;
+		goto out_free;
 	}
 
 	trace = &top->trace;
@@ -620,14 +620,14 @@ int timerlat_top_main(int argc, char *argv[])
 	retval = enable_timerlat(trace);
 	if (retval) {
 		err_msg("Failed to enable timerlat tracer\n");
-		goto out_top;
+		goto out_free;
 	}
 
 	if (params->set_sched) {
 		retval = set_comm_sched_attr("timerlat/", &params->sched_param);
 		if (retval) {
 			err_msg("Failed to set sched parameters\n");
-			goto out_top;
+			goto out_free;
 		}
 	}
 
@@ -635,7 +635,7 @@ int timerlat_top_main(int argc, char *argv[])
 		dma_latency_fd = set_cpu_dma_latency(params->dma_latency);
 		if (dma_latency_fd < 0) {
 			err_msg("Could not set /dev/cpu_dma_latency.\n");
-			goto out_top;
+			goto out_free;
 		}
 	}
 
@@ -645,7 +645,7 @@ int timerlat_top_main(int argc, char *argv[])
 		record = osnoise_init_trace_tool("timerlat");
 		if (!record) {
 			err_msg("Failed to enable the trace instance\n");
-			goto out_top;
+			goto out_free;
 		}
 
 		if (params->events) {
@@ -699,6 +699,7 @@ out_top:
 		close(dma_latency_fd);
 	trace_events_destroy(&record->trace, params->events);
 	params->events = NULL;
+out_free:
 	timerlat_free_top(top->data);
 	osnoise_destroy_tool(record);
 	osnoise_destroy_tool(top);

tools/tracing/rtla/src/utils.c

@@ -3,7 +3,7 @@
  * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
  */
 
-#include <proc/readproc.h>
+#include <dirent.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
@@ -255,50 +255,114 @@ int __set_sched_attr(int pid, struct sched_attr *attr)
 
 	retval = sched_setattr(pid, attr, flags);
 	if (retval < 0) {
-		err_msg("boost_with_deadline failed to boost pid %d: %s\n",
+		err_msg("Failed to set sched attributes to the pid %d: %s\n",
 			pid, strerror(errno));
 		return 1;
 	}
 
 	return 0;
 }
+
 /*
- * set_comm_sched_attr - set sched params to threads starting with char *comm
+ * procfs_is_workload_pid - check if a procfs entry contains a comm_prefix* comm
  *
- * This function uses procps to list the currently running threads and then
+ * Check if the procfs entry is a directory of a process, and then check if the
- * set the sched_attr *attr to the threads that start with char *comm. It is
+ * process has a comm with the prefix set in char *comm_prefix. As the
+ * current users of this function only check for kernel threads, there is no
+ * need to check for the threads for the process.
+ *
+ * Return: True if the proc_entry contains a comm file with comm_prefix*.
+ * Otherwise returns false.
+ */
+static int procfs_is_workload_pid(const char *comm_prefix, struct dirent *proc_entry)
+{
+	char buffer[MAX_PATH];
+	int comm_fd, retval;
+	char *t_name;
+
+	if (proc_entry->d_type != DT_DIR)
+		return 0;
+
+	if (*proc_entry->d_name == '.')
+		return 0;
+
+	/* check if the string is a pid */
+	for (t_name = proc_entry->d_name; t_name; t_name++) {
+		if (!isdigit(*t_name))
+			break;
+	}
+
+	if (*t_name != '\0')
+		return 0;
+
+	snprintf(buffer, MAX_PATH, "/proc/%s/comm", proc_entry->d_name);
+	comm_fd = open(buffer, O_RDONLY);
+	if (comm_fd < 0)
+		return 0;
+
+	memset(buffer, 0, MAX_PATH);
+	retval = read(comm_fd, buffer, MAX_PATH);
+
+	close(comm_fd);
+
+	if (retval <= 0)
+		return 0;
+
+	retval = strncmp(comm_prefix, buffer, strlen(comm_prefix));
+	if (retval)
+		return 0;
+
+	/* comm already have \n */
+	debug_msg("Found workload pid:%s comm:%s", proc_entry->d_name, buffer);
+
+	return 1;
+}
+
+/*
+ * set_comm_sched_attr - set sched params to threads starting with char *comm_prefix
+ *
+ * This function uses procfs to list the currently running threads and then set the
+ * sched_attr *attr to the threads that start with char *comm_prefix. It is
  * mainly used to set the priority to the kernel threads created by the
  * tracers.
  */
-int set_comm_sched_attr(const char *comm, struct sched_attr *attr)
+int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr)
 {
-	int flags = PROC_FILLCOM | PROC_FILLSTAT;
+	struct dirent *proc_entry;
-	PROCTAB *ptp;
+	DIR *procfs;
-	proc_t task;
 	int retval;
 
-	ptp = openproc(flags);
+	if (strlen(comm_prefix) >= MAX_PATH) {
-	if (!ptp) {
+		err_msg("Command prefix is too long: %d < strlen(%s)\n",
-		err_msg("error openproc()\n");
+			MAX_PATH, comm_prefix);
-		return -ENOENT;
+		return 1;
 	}
 
-	memset(&task, 0, sizeof(task));
+	procfs = opendir("/proc");
+	if (!procfs) {
+		err_msg("Could not open procfs\n");
+		return 1;
+	}
 
-	while (readproc(ptp, &task)) {
+	while ((proc_entry = readdir(procfs))) {
-		retval = strncmp(comm, task.cmd, strlen(comm));
+
-		if (retval)
+		retval = procfs_is_workload_pid(comm_prefix, proc_entry);
+		if (!retval)
 			continue;
-		retval = __set_sched_attr(task.tid, attr);
-		if (retval)
-			goto out_err;
-	}
 
-	closeproc(ptp);
+		/* procfs_is_workload_pid confirmed it is a pid */
+		retval = __set_sched_attr(atoi(proc_entry->d_name), attr);
+		if (retval) {
+			err_msg("Error setting sched attributes for pid:%s\n", proc_entry->d_name);
+			goto out_err;
+		}
+
+		debug_msg("Set sched attributes for pid:%s\n", proc_entry->d_name);
+	}
 	return 0;
 
 out_err:
-	closeproc(ptp);
+	closedir(procfs);
 	return 1;
 }
 

tools/tracing/rtla/src/utils.h

@@ -6,6 +6,7 @@
  * '18446744073709551615\0'
  */
 #define BUFF_U64_STR_SIZE	24
+#define MAX_PATH		1024
 
 #define container_of(ptr, type, member)({			\
 	const typeof(((type *)0)->member) *__mptr = (ptr);	\
@@ -53,5 +54,5 @@ struct sched_attr {
 };
 
 int parse_prio(char *arg, struct sched_attr *sched_param);
-int set_comm_sched_attr(const char *comm, struct sched_attr *attr);
+int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr);
 int set_cpu_dma_latency(int32_t latency);