[for-next][PATCH 0/5] tracing: Final updates for 7.1

[for-next][PATCH 0/5] tracing: Final updates for 7.1

[Steven Rostedt]

Small cleanups fixes and updates for 7.1

  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace/for-next

Head SHA1: 621a59d8fc678762abc12ad8ad6bf616496fa4d2


CaoRuichuang (1):
      tracing: Report ipi_raise target CPUs as cpumask

David Carlier (1):
      tracepoint: balance regfunc() on func_add() failure in tracepoint_add_func()

Pengpeng Hou (1):
      tracing: Rebuild full_name on each hist_field_name() call

Tom Zanussi (2):
      tracing: Fix fully-qualified variable reference printing in histograms
      selftests/ftrace: Add test case for fully-qualified variable references

----
 include/trace/events/ipi.h                         |  6 ++--
 kernel/trace/trace_events_hist.c                   | 25 ++++++++++------
 kernel/tracepoint.c                                |  2 ++
 .../inter-event/trigger-fully-qualified-var-ref.tc | 34 ++++++++++++++++++++++
 4 files changed, 55 insertions(+), 12 deletions(-)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-fully-qualified-var-ref.tc

[for-next][PATCH 1/5] tracing: Report ipi_raise target CPUs as cpumask

[Steven Rostedt]

From: CaoRuichuang <create0818@163.com>

Bugzilla 217447 points out that ftrace bitmask fields still use the
legacy dynamic-array format, which makes trace consumers treat them
as unsigned long arrays instead of bitmaps.

This is visible in the ipi events today: ipi_send_cpumask already
reports its CPU mask as '__data_loc cpumask_t', but ipi_raise still
exposes target_cpus as '__data_loc unsigned long[]'.

Switch ipi_raise to __cpumask() and the matching helpers so its
tracefs format matches the existing cpumask representation used by
the other ipi event. The underlying storage size stays the same, but
trace data consumers can now recognize the field as a cpumask
directly.

Link: https://patch.msgid.link/20260406162434.40767-1-create0818@163.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217447
Signed-off-by: CaoRuichuang <create0818@163.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 include/trace/events/ipi.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/trace/events/ipi.h b/include/trace/events/ipi.h
index 9912f0ded81d..fae4f8eac411 100644
--- a/include/trace/events/ipi.h
+++ b/include/trace/events/ipi.h
@@ -68,16 +68,16 @@ TRACE_EVENT(ipi_raise,
 	TP_ARGS(mask, reason),
 
 	TP_STRUCT__entry(
-		__bitmask(target_cpus, nr_cpumask_bits)
+		__cpumask(target_cpus)
 		__field(const char *, reason)
 	),
 
 	TP_fast_assign(
-		__assign_bitmask(target_cpus, cpumask_bits(mask), nr_cpumask_bits);
+		__assign_cpumask(target_cpus, cpumask_bits(mask));
 		__entry->reason = reason;
 	),
 
-	TP_printk("target_mask=%s (%s)", __get_bitmask(target_cpus), __entry->reason)
+	TP_printk("target_mask=%s (%s)", __get_cpumask(target_cpus), __entry->reason)
 );
 
 DECLARE_EVENT_CLASS(ipi_handler,
-- 
2.51.0

[for-next][PATCH 2/5] tracing: Rebuild full_name on each hist_field_name() call

[Steven Rostedt]

From: Pengpeng Hou <pengpeng@iscas.ac.cn>

hist_field_name() uses a static MAX_FILTER_STR_VAL buffer for fully
qualified variable-reference names, but it currently appends into that
buffer with strcat() without rebuilding it first. As a result, repeated
calls append a new "system.event.field" name onto the previous one,
which can eventually run past the end of full_name.

Build the name with snprintf() on each call and return NULL if the fully
qualified name does not fit in MAX_FILTER_STR_VAL.

Link: https://patch.msgid.link/20260401112224.85582-1-pengpeng@iscas.ac.cn
Fixes: 067fe038e70f ("tracing: Add variable reference handling to hist triggers")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Tested-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_events_hist.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 67cb92310864..b2b675c7d663 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1361,12 +1361,14 @@ static const char *hist_field_name(struct hist_field *field,
 		 field->flags & HIST_FIELD_FL_VAR_REF) {
 		if (field->system) {
 			static char full_name[MAX_FILTER_STR_VAL];
+			int len;
+
+			len = snprintf(full_name, sizeof(full_name), "%s.%s.%s",
+				       field->system, field->event_name,
+				       field->name);
+			if (len >= sizeof(full_name))
+				return NULL;
 
-			strcat(full_name, field->system);
-			strcat(full_name, ".");
-			strcat(full_name, field->event_name);
-			strcat(full_name, ".");
-			strcat(full_name, field->name);
 			field_name = full_name;
 		} else
 			field_name = field->name;
-- 
2.51.0

[for-next][PATCH 3/5] tracepoint: balance regfunc() on func_add() failure in tracepoint_add_func()

[Steven Rostedt]

From: David Carlier <devnexen@gmail.com>

When a tracepoint goes through the 0 -> 1 transition, tracepoint_add_func()
invokes the subsystem's ext->regfunc() before attempting to install the
new probe via func_add(). If func_add() then fails (for example, when
allocate_probes() cannot allocate a new probe array under memory pressure
and returns -ENOMEM), the function returns the error without calling the
matching ext->unregfunc(), leaving the side effects of regfunc() behind
with no installed probe to justify them.

For syscall tracepoints this is particularly unpleasant: syscall_regfunc()
bumps sys_tracepoint_refcount and sets SYSCALL_TRACEPOINT on every task.
After a leaked failure, the refcount is stuck at a non-zero value with no
consumer, and every task continues paying the syscall trace entry/exit
overhead until reboot. Other subsystems providing regfunc()/unregfunc()
pairs exhibit similarly scoped persistent state.

Mirror the existing 1 -> 0 cleanup and call ext->unregfunc() in the
func_add() error path, gated on the same condition used there so the
unwind is symmetric with the registration.

Fixes: 8cf868affdc4 ("tracing: Have the reg function allow to fail")
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260413190601.21993-1-devnexen@gmail.com
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/tracepoint.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 91905aa19294..dffef52a807b 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -300,6 +300,8 @@ static int tracepoint_add_func(struct tracepoint *tp,
 			lockdep_is_held(&tracepoints_mutex));
 	old = func_add(&tp_funcs, func, prio);
 	if (IS_ERR(old)) {
+		if (tp->ext && tp->ext->unregfunc && !static_key_enabled(&tp->key))
+			tp->ext->unregfunc();
 		WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM);
 		return PTR_ERR(old);
 	}
-- 
2.51.0

[for-next][PATCH 4/5] tracing: Fix fully-qualified variable reference printing in histograms

[Steven Rostedt]

From: Tom Zanussi <zanussi@kernel.org>

The syntax for fully-qualified variable references in histograms is
subsys.event.$var, which is parsed correctly, but not displayed correctly
when printing a histogram spec. The current code puts the $ reference at
the beginning of the fully-qualified variable name i.e. $subsys.event.var,
which is incorrect.

Before:

trigger info: hist:keys=next_comm:vals=hitcount:wakeup_lat=common_timestamp.usecs-$sched.sched_wakeup.ts0: ...

After:

trigger info: hist:keys=next_comm:vals=hitcount:wakeup_lat=common_timestamp.usecs-sched.sched_wakeup.$ts0: ...

Link: https://patch.msgid.link/5dee9a86d062a4dd68c2214f3d90ac93811e1951.1776112478.git.zanussi@kernel.org
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_events_hist.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index b2b675c7d663..0dbbf6cca9bc 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1361,9 +1361,12 @@ static const char *hist_field_name(struct hist_field *field,
 		 field->flags & HIST_FIELD_FL_VAR_REF) {
 		if (field->system) {
 			static char full_name[MAX_FILTER_STR_VAL];
+			static char *fmt;
 			int len;
 
-			len = snprintf(full_name, sizeof(full_name), "%s.%s.%s",
+			fmt = field->flags & HIST_FIELD_FL_VAR_REF ? "%s.%s.$%s" : "%s.%s.%s";
+
+			len = snprintf(full_name, sizeof(full_name), fmt,
 				       field->system, field->event_name,
 				       field->name);
 			if (len >= sizeof(full_name))
@@ -1742,9 +1745,10 @@ static const char *get_hist_field_flags(struct hist_field *hist_field)
 
 static void expr_field_str(struct hist_field *field, char *expr)
 {
-	if (field->flags & HIST_FIELD_FL_VAR_REF)
-		strcat(expr, "$");
-	else if (field->flags & HIST_FIELD_FL_CONST) {
+	if (field->flags & HIST_FIELD_FL_VAR_REF) {
+		if (!field->system)
+			strcat(expr, "$");
+	} else if (field->flags & HIST_FIELD_FL_CONST) {
 		char str[HIST_CONST_DIGITS_MAX];
 
 		snprintf(str, HIST_CONST_DIGITS_MAX, "%llu", field->constant);
@@ -6156,7 +6160,8 @@ static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
 	else if (field_name) {
 		if (hist_field->flags & HIST_FIELD_FL_VAR_REF ||
 		    hist_field->flags & HIST_FIELD_FL_ALIAS)
-			seq_putc(m, '$');
+			if (!hist_field->system)
+				seq_putc(m, '$');
 		seq_printf(m, "%s", field_name);
 	} else if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP)
 		seq_puts(m, "common_timestamp");
-- 
2.51.0

[for-next][PATCH 5/5] selftests/ftrace: Add test case for fully-qualified variable references

[Steven Rostedt]

From: Tom Zanussi <zanussi@kernel.org>

This test adds a variable (ts0) to two events (sched_waking and
sched_wakeup) and uses a fully-qualified variable reference to expicitly
choose a particular one (sched_wakeup.$ts0) when calculating the wakeup
latency.

Link: https://patch.msgid.link/ce9d96aeb84b2d40bd469fe9a346e225442873b1.1776112478.git.zanussi@kernel.org
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 .../trigger-fully-qualified-var-ref.tc        | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-fully-qualified-var-ref.tc

diff --git a/tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-fully-qualified-var-ref.tc b/tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-fully-qualified-var-ref.tc
new file mode 100644
index 000000000000..8d12cdd06f1d
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-fully-qualified-var-ref.tc
@@ -0,0 +1,34 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test fully-qualified variable reference support
+# requires: set_event synthetic_events events/sched/sched_process_fork/hist ping:program
+
+fail() { #msg
+    echo $1
+    exit_fail
+}
+
+echo "Test fully-qualified variable reference support"
+
+echo 'wakeup_latency u64 lat; pid_t pid; int prio; char comm[16]' > synthetic_events
+echo 'hist:keys=comm:ts0=common_timestamp.usecs if comm=="ping"' > events/sched/sched_waking/trigger
+echo 'hist:keys=comm:ts0=common_timestamp.usecs if comm=="ping"' > events/sched/sched_wakeup/trigger
+echo 'hist:keys=next_comm:wakeup_lat=common_timestamp.usecs-sched.sched_wakeup.$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid,sched.sched_waking.prio,next_comm) if next_comm=="ping"' > events/sched/sched_switch/trigger
+echo 'hist:keys=pid,prio,comm:vals=lat:sort=pid,prio' > events/synthetic/wakeup_latency/trigger
+
+ping $LOCALHOST -c 3
+if ! grep -q "ping" events/synthetic/wakeup_latency/hist; then
+    fail "Failed to create inter-event histogram"
+fi
+
+if ! grep -q "synthetic_prio=prio" events/sched/sched_waking/hist; then
+    fail "Failed to create histogram with fully-qualified variable reference"
+fi
+
+echo '!hist:keys=next_comm:wakeup_lat=common_timestamp.usecs-sched.sched_wakeup.$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid,sched.sched_waking.prio,next_comm) if next_comm=="ping"' >> events/sched/sched_switch/trigger
+
+if grep -q "synthetic_prio=prio" events/sched/sched_waking/hist; then
+    fail "Failed to remove histogram with fully-qualified variable reference"
+fi
+
+exit 0
-- 
2.51.0