Merge tag 'trace-v6.14-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:

 - Cleanup with guard() and free() helpers

   There were several places in the code that had a lot of "goto out" in
   the error paths to either unlock a lock or free some memory that was
   allocated. But this is error prone. Convert the code over to use the
   guard() and free() helpers that let the compiler unlock locks or free
   memory when the function exits.

 - Update the Rust tracepoint code to use the C code too

   There was some duplication of the tracepoint code for Rust that did
   the same logic as the C code. Add a helper that makes it possible for
   both algorithms to use the same logic in one place.

 - Add poll to trace event hist files

   It is useful to know when an event is triggered, or even with some
   filtering. Since hist files of events get updated when active and the
   event is triggered, allow applications to poll the hist file and wake
   up when an event is triggered. This will let the application know
   that the event it is waiting for happened.

 - Add :mod: command to enable events for current or future modules

   The function tracer already has a way to enable functions to be
   traced in modules by writing ":mod:<module>" into set_ftrace_filter.
   That will enable either all the functions for the module if it is
   loaded, or if it is not, it will cache that command, and when the
   module is loaded that matches <module>, its functions will be
   enabled. This also allows init functions to be traced. But currently
   events do not have that feature.

   Add the command where if ':mod:<module>' is written into set_event,
   then either all the modules events are enabled if it is loaded, or
   cache it so that the module's events are enabled when it is loaded.
   This also works from the kernel command line, where
   "trace_event=:mod:<module>", when the module is loaded at boot up,
   its events will be enabled then.

* tag 'trace-v6.14-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (26 commits)
  tracing: Fix output of set_event for some cached module events
  tracing: Fix allocation of printing set_event file content
  tracing: Rename update_cache() to update_mod_cache()
  tracing: Fix #if CONFIG_MODULES to #ifdef CONFIG_MODULES
  selftests/ftrace: Add test that tests event :mod: commands
  tracing: Cache ":mod:" events for modules not loaded yet
  tracing: Add :mod: command to enabled module events
  selftests/tracing: Add hist poll() support test
  tracing/hist: Support POLLPRI event for poll on histogram
  tracing/hist: Add poll(POLLIN) support on hist file
  tracing: Fix using ret variable in tracing_set_tracer()
  tracepoint: Reduce duplication of __DO_TRACE_CALL
  tracing/string: Create and use __free(argv_free) in trace_dynevent.c
  tracing: Switch trace_stat.c code over to use guard()
  tracing: Switch trace_stack.c code over to use guard()
  tracing: Switch trace_osnoise.c code over to use guard() and __free()
  tracing: Switch trace_events_synth.c code over to use guard()
  tracing: Switch trace_events_filter.c code over to use guard()
  tracing: Switch trace_events_trigger.c code over to use guard()
  tracing: Switch trace_events_hist.c code over to use guard()
  ...

4 files changed, 341 insertions, 0 deletions

diff --git a/tools/testing/selftests/ftrace/Makefile b/tools/testing/selftests/ftrace/Makefile
index a1e955d2de4c..49d96bb16355 100644
--- a/tools/testing/selftests/ftrace/Makefile
+++ b/tools/testing/selftests/ftrace/Makefile
@@ -6,4 +6,6 @@ TEST_PROGS := ftracetest-ktap
 TEST_FILES := test.d settings
 EXTRA_CLEAN := $(OUTPUT)/logs/*
 
+TEST_GEN_PROGS = poll
+
 include ../lib.mk
diff --git a/tools/testing/selftests/ftrace/poll.c b/tools/testing/selftests/ftrace/poll.c
new file mode 100644
index 000000000000..53258f7515e7
--- /dev/null
+++ b/tools/testing/selftests/ftrace/poll.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple poll on a file.
+ *
+ * Copyright (c) 2024 Google LLC.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define BUFSIZE 4096
+
+/*
+ * Usage:
+ *  poll [-I|-P] [-t timeout] FILE
+ */
+int main(int argc, char *argv[])
+{
+	struct pollfd pfd = {.events = POLLIN};
+	char buf[BUFSIZE];
+	int timeout = -1;
+	int ret, opt;
+
+	while ((opt = getopt(argc, argv, "IPt:")) != -1) {
+		switch (opt) {
+		case 'I':
+			pfd.events = POLLIN;
+			break;
+		case 'P':
+			pfd.events = POLLPRI;
+			break;
+		case 't':
+			timeout = atoi(optarg);
+			break;
+		default:
+			fprintf(stderr, "Usage: %s [-I|-P] [-t timeout] FILE\n",
+				argv[0]);
+			return -1;
+		}
+	}
+	if (optind >= argc) {
+		fprintf(stderr, "Error: Polling file is not specified\n");
+		return -1;
+	}
+
+	pfd.fd = open(argv[optind], O_RDONLY);
+	if (pfd.fd < 0) {
+		fprintf(stderr, "failed to open %s", argv[optind]);
+		perror("open");
+		return -1;
+	}
+
+	/* Reset poll by read if POLLIN is specified. */
+	if (pfd.events & POLLIN)
+		do {} while (read(pfd.fd, buf, BUFSIZE) == BUFSIZE);
+
+	ret = poll(&pfd, 1, timeout);
+	if (ret < 0 && errno != EINTR) {
+		perror("poll");
+		return -1;
+	}
+	close(pfd.fd);
+
+	/* If timeout happned (ret == 0), exit code is 1 */
+	if (ret == 0)
+		return 1;
+
+	return 0;
+}
diff --git a/tools/testing/selftests/ftrace/test.d/event/event-mod.tc b/tools/testing/selftests/ftrace/test.d/event/event-mod.tc
new file mode 100644
index 000000000000..175243cd9ab7
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/event/event-mod.tc
@@ -0,0 +1,191 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event tracing - enable/disable with module event
+# requires: set_event "Can enable module events via: :mod:":README
+# flags: instance
+
+rmmod trace-events-sample ||:
+if ! modprobe trace-events-sample ; then
+  echo "No trace-events sample module - please make CONFIG_SAMPLE_TRACE_EVENTS=m"
+  exit_unresolved;
+fi
+trap "rmmod trace-events-sample" EXIT
+
+# Set events for the module
+echo ":mod:trace-events-sample" > set_event
+
+test_all_enabled() {
+
+	# Check if more than one is enabled
+	grep -q sample-trace:foo_bar set_event
+	grep -q sample-trace:foo_bar_with_cond set_event
+	grep -q sample-trace:foo_bar_with_fn set_event
+
+	# All of them should be enabled. Check via the enable file
+	val=`cat events/sample-trace/enable`
+	if [ $val -ne 1 ]; then
+		exit_fail
+	fi
+}
+
+clear_events() {
+	echo > set_event
+	val=`cat events/enable`
+	if [ "$val" != "0" ]; then
+		exit_fail
+	fi
+	count=`cat set_event | wc -l`
+	if [ $count -ne 0 ]; then
+		exit_fail
+	fi
+}
+
+test_all_enabled
+
+echo clear all events
+echo 0 > events/enable
+
+echo Confirm the events are disabled
+val=`cat events/sample-trace/enable`
+if [ $val -ne 0 ]; then
+	exit_fail
+fi
+
+echo And the set_event file is empty
+
+cnt=`wc -l set_event`
+if [ $cnt -ne 0 ]; then
+	exit_fail
+fi
+
+echo now enable all events
+echo 1 > events/enable
+
+echo Confirm the events are enabled again
+val=`cat events/sample-trace/enable`
+if [ $val -ne 1 ]; then
+	exit_fail
+fi
+
+echo disable just the module events
+echo '!:mod:trace-events-sample' >> set_event
+
+echo Should have mix of events enabled
+val=`cat events/enable`
+if [ "$val" != "X" ]; then
+	exit_fail
+fi
+
+echo Confirm the module events are disabled
+val=`cat events/sample-trace/enable`
+if [ $val -ne 0 ]; then
+	exit_fail
+fi
+
+echo 0 > events/enable
+
+echo now enable the system events
+echo 'sample-trace:mod:trace-events-sample' > set_event
+
+test_all_enabled
+
+echo clear all events
+echo 0 > events/enable
+
+echo Confirm the events are disabled
+val=`cat events/sample-trace/enable`
+if [ $val -ne 0 ]; then
+	exit_fail
+fi
+
+echo Test enabling foo_bar only
+echo 'foo_bar:mod:trace-events-sample' > set_event
+
+grep -q sample-trace:foo_bar set_event
+
+echo make sure nothing is found besides foo_bar
+if grep -q -v sample-trace:foo_bar set_event ; then
+	exit_fail
+fi
+
+echo Append another using the system and event name
+echo 'sample-trace:foo_bar_with_cond:mod:trace-events-sample' >> set_event
+
+grep -q sample-trace:foo_bar set_event
+grep -q sample-trace:foo_bar_with_cond set_event
+
+count=`cat set_event | wc -l`
+
+if [ $count -ne 2 ]; then
+	exit_fail
+fi
+
+clear_events
+
+rmmod trace-events-sample
+
+echo ':mod:trace-events-sample' > set_event
+
+echo make sure that the module shows up, and '-' is converted to '_'
+grep -q '\*:\*:mod:trace_events_sample' set_event
+
+modprobe trace-events-sample
+
+test_all_enabled
+
+clear_events
+
+rmmod trace-events-sample
+
+echo Enable just the system events
+echo 'sample-trace:mod:trace-events-sample' > set_event
+grep -q 'sample-trace:mod:trace_events_sample' set_event
+
+modprobe trace-events-sample
+
+test_all_enabled
+
+clear_events
+
+rmmod trace-events-sample
+
+echo Enable event with just event name
+echo 'foo_bar:mod:trace-events-sample' > set_event
+grep -q 'foo_bar:mod:trace_events_sample' set_event
+
+echo Enable another event with both system and event name
+echo 'sample-trace:foo_bar_with_cond:mod:trace-events-sample' >> set_event
+grep -q 'sample-trace:foo_bar_with_cond:mod:trace_events_sample' set_event
+echo Make sure the other event was still there
+grep -q 'foo_bar:mod:trace_events_sample' set_event
+
+modprobe trace-events-sample
+
+echo There should be no :mod: cached events
+if grep -q ':mod:' set_event; then
+	exit_fail
+fi
+
+echo two events should be enabled
+count=`cat set_event | wc -l`
+if [ $count -ne 2 ]; then
+	exit_fail
+fi
+
+echo only two events should be enabled
+val=`cat events/sample-trace/enable`
+if [ "$val" != "X" ]; then
+	exit_fail
+fi
+
+val=`cat events/sample-trace/foo_bar/enable`
+if [ "$val" != "1" ]; then
+	exit_fail
+fi
+
+val=`cat events/sample-trace/foo_bar_with_cond/enable`
+if [ "$val" != "1" ]; then
+	exit_fail
+fi
+
+clear_trace
diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc
new file mode 100644
index 000000000000..8d275e3238d9
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc
@@ -0,0 +1,74 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test poll wait on histogram
+# requires: set_event events/sched/sched_process_free/trigger events/sched/sched_process_free/hist
+# flags: instance
+
+POLL=${FTRACETEST_ROOT}/poll
+
+if [ ! -x ${POLL} ]; then
+  echo "poll program is not compiled!"
+  exit_unresolved
+fi
+
+EVENT=events/sched/sched_process_free/
+
+# Check poll ops is supported. Before implementing poll on hist file, it
+# returns soon with POLLIN | POLLOUT, but not POLLPRI.
+
+# This must wait >1 sec and return 1 (timeout).
+set +e
+${POLL} -I -t 1000 ${EVENT}/hist
+ret=$?
+set -e
+if [ ${ret} != 1 ]; then
+  echo "poll on hist file is not supported"
+  exit_unsupported
+fi
+
+# Test POLLIN
+echo > trace
+echo 'hist:key=comm if comm =="sleep"' > ${EVENT}/trigger
+echo 1 > ${EVENT}/enable
+
+# This sleep command will exit after 2 seconds.
+sleep 2 &
+BGPID=$!
+# if timeout happens, poll returns 1.
+${POLL} -I -t 4000 ${EVENT}/hist
+echo 0 > tracing_on
+
+if [ -d /proc/${BGPID} ]; then
+  echo "poll exits too soon"
+  kill -KILL ${BGPID} ||:
+  exit_fail
+fi
+
+if ! grep -qw "sleep" trace; then
+  echo "poll exits before event happens"
+  exit_fail
+fi
+
+# Test POLLPRI
+echo > trace
+echo 1 > tracing_on
+
+# This sleep command will exit after 2 seconds.
+sleep 2 &
+BGPID=$!
+# if timeout happens, poll returns 1.
+${POLL} -P -t 4000 ${EVENT}/hist
+echo 0 > tracing_on
+
+if [ -d /proc/${BGPID} ]; then
+  echo "poll exits too soon"
+  kill -KILL ${BGPID} ||:
+  exit_fail
+fi
+
+if ! grep -qw "sleep" trace; then
+  echo "poll exits before event happens"
+  exit_fail
+fi
+
+exit_pass