[for-next][PATCH 0/8] tracing: Updates for v6.17

[for-next][PATCH 0/8] tracing: Updates for v6.17

[Steven Rostedt]

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

Head SHA1: 9ba817fb7c6afd3c86a6d4c3b822924b87ef0348


Arnd Bergmann (1):
      kernel: trace: preemptirq_delay_test: use offstack cpu mask

Nam Cao (1):
      tracing: Remove pointless memory barriers

Ricardo Neri (1):
      tracing/sched: Remove obsolete comment on suffixes

Steven Rostedt (4):
      tracing: Use queue_rcu_work() to free filters
      tracing: Remove EVENT_FILE_FL_SOFT_MODE flag
      tracing: Fix comment in trace_module_remove_events()
      tracing: Deprecate auto-mounting tracefs in debugfs

Yury Norov (1):
      tracing: Replace opencoded cpumask_next_wrap() in move_to_next_cpu()

----
 .../ABI/obsolete/automount-tracefs-debugfs         | 20 ++++++++++++++++
 include/linux/trace_events.h                       |  3 ---
 include/trace/events/sched.h                       |  2 --
 kernel/trace/Kconfig                               | 13 ++++++++++
 kernel/trace/preemptirq_delay_test.c               | 13 ++++++----
 kernel/trace/rv/rv.c                               |  6 -----
 kernel/trace/trace.c                               | 21 ++++++++--------
 kernel/trace/trace_events.c                        | 26 ++++++++++----------
 kernel/trace/trace_events_filter.c                 | 28 +++++++++++++++-------
 kernel/trace/trace_hwlat.c                         |  5 +---
 10 files changed, 86 insertions(+), 51 deletions(-)
 create mode 100644 Documentation/ABI/obsolete/automount-tracefs-debugfs

[for-next][PATCH 1/8] tracing: Replace opencoded cpumask_next_wrap() in move_to_next_cpu()

[Steven Rostedt]

From: Yury Norov <yury.norov@gmail.com>

The dedicated cpumask_next_wrap() is more verbose and effective than
cpumask_next() followed by cpumask_first().

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250605000651.45281-1-yury.norov@gmail.com
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_hwlat.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index b65353ec2837..2f7b94e98317 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -325,12 +325,9 @@ static void move_to_next_cpu(void)
 
 	cpus_read_lock();
 	cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
-	next_cpu = cpumask_next(raw_smp_processor_id(), current_mask);
+	next_cpu = cpumask_next_wrap(raw_smp_processor_id(), current_mask);
 	cpus_read_unlock();
 
-	if (next_cpu >= nr_cpu_ids)
-		next_cpu = cpumask_first(current_mask);
-
 	if (next_cpu >= nr_cpu_ids) /* Shouldn't happen! */
 		goto change_mode;
 
-- 
2.47.2

[for-next][PATCH 2/8] tracing: Use queue_rcu_work() to free filters

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

Freeing of filters requires to wait for both an RCU grace period as well as
a RCU task trace wait period after they have been detached from their
lists. The trace task period can be quite large so the freeing of the
filters was moved to use the call_rcu*() routines. The problem with that is
that the callback functions of call_rcu*() is done from a soft irq and can
cause latencies if the callback takes a bit of time.

The filters are freed per event in a system and the syscalls system
contains an event per system call, which can be over 700 events. Freeing 700
filters in a bottom half is undesirable.

Instead, move the freeing to use queue_rcu_work() which is done in task
context.

Link: https://lore.kernel.org/all/9a2f0cd0-1561-4206-8966-f93ccd25927f@paulmck-laptop/

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250609131732.04fd303b@gandalf.local.home
Fixes: a9d0aab5eb33 ("tracing: Fix regression of filter waiting a long time on RCU synchronization")
Suggested-by: "Paul E. McKenney" <paulmck@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_events_filter.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 3885aadc434d..196c8bf34970 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1344,13 +1344,14 @@ struct filter_list {
 
 struct filter_head {
 	struct list_head	list;
-	struct rcu_head		rcu;
+	union {
+		struct rcu_head		rcu;
+		struct rcu_work		rwork;
+	};
 };
 
-
-static void free_filter_list(struct rcu_head *rhp)
+static void free_filter_list(struct filter_head *filter_list)
 {
-	struct filter_head *filter_list = container_of(rhp, struct filter_head, rcu);
 	struct filter_list *filter_item, *tmp;
 
 	list_for_each_entry_safe(filter_item, tmp, &filter_list->list, list) {
@@ -1361,9 +1362,20 @@ static void free_filter_list(struct rcu_head *rhp)
 	kfree(filter_list);
 }
 
+static void free_filter_list_work(struct work_struct *work)
+{
+	struct filter_head *filter_list;
+
+	filter_list = container_of(to_rcu_work(work), struct filter_head, rwork);
+	free_filter_list(filter_list);
+}
+
 static void free_filter_list_tasks(struct rcu_head *rhp)
 {
-	call_rcu(rhp, free_filter_list);
+	struct filter_head *filter_list = container_of(rhp, struct filter_head, rcu);
+
+	INIT_RCU_WORK(&filter_list->rwork, free_filter_list_work);
+	queue_rcu_work(system_wq, &filter_list->rwork);
 }
 
 /*
@@ -1460,7 +1472,7 @@ static void filter_free_subsystem_filters(struct trace_subsystem_dir *dir,
 	tracepoint_synchronize_unregister();
 
 	if (head)
-		free_filter_list(&head->rcu);
+		free_filter_list(head);
 
 	list_for_each_entry(file, &tr->events, list) {
 		if (file->system != dir || !file->filter)
@@ -2305,7 +2317,7 @@ static int process_system_preds(struct trace_subsystem_dir *dir,
 	return 0;
  fail:
 	/* No call succeeded */
-	free_filter_list(&filter_list->rcu);
+	free_filter_list(filter_list);
 	parse_error(pe, FILT_ERR_BAD_SUBSYS_FILTER, 0);
 	return -EINVAL;
  fail_mem:
@@ -2315,7 +2327,7 @@ static int process_system_preds(struct trace_subsystem_dir *dir,
 	if (!fail)
 		delay_free_filter(filter_list);
 	else
-		free_filter_list(&filter_list->rcu);
+		free_filter_list(filter_list);
 
 	return -ENOMEM;
 }
-- 
2.47.2

[for-next][PATCH 3/8] kernel: trace: preemptirq_delay_test: use offstack cpu mask

[Steven Rostedt]

From: Arnd Bergmann <arnd@arndb.de>

A CPU mask on the stack is broken for large values of CONFIG_NR_CPUS:

kernel/trace/preemptirq_delay_test.c: In function ‘preemptirq_delay_run’:
kernel/trace/preemptirq_delay_test.c:143:1: error: the frame size of 8512 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]

Fall back to dynamic allocation here.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Song Chen <chensong_2000@189.cn>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250620111215.3365305-1-arnd@kernel.org
Fixes: 4b9091e1c194 ("kernel: trace: preemptirq_delay_test: add cpu affinity")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/preemptirq_delay_test.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/preemptirq_delay_test.c b/kernel/trace/preemptirq_delay_test.c
index 314ffc143039..acb0c971a408 100644
--- a/kernel/trace/preemptirq_delay_test.c
+++ b/kernel/trace/preemptirq_delay_test.c
@@ -117,12 +117,15 @@ static int preemptirq_delay_run(void *data)
 {
 	int i;
 	int s = MIN(burst_size, NR_TEST_FUNCS);
-	struct cpumask cpu_mask;
+	cpumask_var_t cpu_mask;
+
+	if (!alloc_cpumask_var(&cpu_mask, GFP_KERNEL))
+		return -ENOMEM;
 
 	if (cpu_affinity > -1) {
-		cpumask_clear(&cpu_mask);
-		cpumask_set_cpu(cpu_affinity, &cpu_mask);
-		if (set_cpus_allowed_ptr(current, &cpu_mask))
+		cpumask_clear(cpu_mask);
+		cpumask_set_cpu(cpu_affinity, cpu_mask);
+		if (set_cpus_allowed_ptr(current, cpu_mask))
 			pr_err("cpu_affinity:%d, failed\n", cpu_affinity);
 	}
 
@@ -139,6 +142,8 @@ static int preemptirq_delay_run(void *data)
 
 	__set_current_state(TASK_RUNNING);
 
+	free_cpumask_var(cpu_mask);
+
 	return 0;
 }
 
-- 
2.47.2

[for-next][PATCH 4/8] tracing/sched: Remove obsolete comment on suffixes

[Steven Rostedt]

From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>

Commit ac01fa73f530 ("tracepoint: Have tracepoints created with DECLARE_
TRACE() have _tp suffix") makes it unnecessary to manually add a suffix.

Remove a now obsolete comment.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Link: https://lore.kernel.org/20250620-rneri-tp-comment-fix-v1-1-e0f6495ac33c@linux.intel.com
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 include/trace/events/sched.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 4e6b2910cec3..f24c373bcc44 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -829,8 +829,6 @@ TRACE_EVENT(sched_wake_idle_without_ipi,
 /*
  * Following tracepoints are not exported in tracefs and provide hooking
  * mechanisms only for testing and debugging purposes.
- *
- * Postfixed with _tp to make them easily identifiable in the code.
  */
 DECLARE_TRACE(pelt_cfs,
 	TP_PROTO(struct cfs_rq *cfs_rq),
-- 
2.47.2

[for-next][PATCH 5/8] tracing: Remove pointless memory barriers

[Steven Rostedt]

From: Nam Cao <namcao@linutronix.de>

Memory barriers are useful to ensure memory accesses from one CPU appear in
the original order as seen by other CPUs.

Some smp_rmb() and smp_wmb() are used, but they are not ordering multiple
memory accesses.

Remove them.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/20250626151940.1756398-1-namcao@linutronix.de
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/rv/rv.c | 6 ------
 kernel/trace/trace.c | 7 -------
 2 files changed, 13 deletions(-)

diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c
index e4077500a91d..c04a49da4328 100644
--- a/kernel/trace/rv/rv.c
+++ b/kernel/trace/rv/rv.c
@@ -675,8 +675,6 @@ static bool __read_mostly monitoring_on;
  */
 bool rv_monitoring_on(void)
 {
-	/* Ensures that concurrent monitors read consistent monitoring_on */
-	smp_rmb();
 	return READ_ONCE(monitoring_on);
 }
 
@@ -696,8 +694,6 @@ static ssize_t monitoring_on_read_data(struct file *filp, char __user *user_buf,
 static void turn_monitoring_off(void)
 {
 	WRITE_ONCE(monitoring_on, false);
-	/* Ensures that concurrent monitors read consistent monitoring_on */
-	smp_wmb();
 }
 
 static void reset_all_monitors(void)
@@ -713,8 +709,6 @@ static void reset_all_monitors(void)
 static void turn_monitoring_on(void)
 {
 	WRITE_ONCE(monitoring_on, true);
-	/* Ensures that concurrent monitors read consistent monitoring_on */
-	smp_wmb();
 }
 
 static void turn_monitoring_on_with_reset(void)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 95ae7c4e5835..0dff4298fc0e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -936,7 +936,6 @@ int tracing_is_enabled(void)
 	 * return the mirror variable of the state of the ring buffer.
 	 * It's a little racy, but we don't really care.
 	 */
-	smp_rmb();
 	return !global_trace.buffer_disabled;
 }
 
@@ -1107,8 +1106,6 @@ void tracer_tracing_on(struct trace_array *tr)
 	 * important to be fast than accurate.
 	 */
 	tr->buffer_disabled = 0;
-	/* Make the flag seen by readers */
-	smp_wmb();
 }
 
 /**
@@ -1640,8 +1637,6 @@ void tracer_tracing_off(struct trace_array *tr)
 	 * important to be fast than accurate.
 	 */
 	tr->buffer_disabled = 1;
-	/* Make the flag seen by readers */
-	smp_wmb();
 }
 
 /**
@@ -2710,8 +2705,6 @@ void trace_buffered_event_enable(void)
 
 static void enable_trace_buffered_event(void *data)
 {
-	/* Probably not needed, but do it anyway */
-	smp_rmb();
 	this_cpu_dec(trace_buffered_event_cnt);
 }
 
-- 
2.47.2

[for-next][PATCH 6/8] tracing: Remove EVENT_FILE_FL_SOFT_MODE flag

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

When soft disabling of trace events was first created, it needed to have a
way to know if a file had a user that was using it with soft disabled (for
triggers that need to enable or disable events from a context that can not
really enable or disable the event, it would set SOFT_DISABLED to state it
is disabled). The flag SOFT_MODE was used to denote that an event had a
user that would enable or disable it via the SOFT_DISABLED flag.

Commit 1cf4c0732db3c ("tracing: Modify soft-mode only if there's no other
referrer") fixed a bug where if two users were using the SOFT_DISABLED
flag the accounting would get messed up as the SOFT_MODE flag could only
handle one user. That commit added the sm_ref counter which kept track of
how many users were using the event in "soft mode". This made the
SOFT_MODE flag redundant as it should only be set if the sm_ref counter is
non zero.

Remove the SOFT_MODE flag and just use the sm_ref counter to know the
event is in soft mode or not. This makes the code a bit simpler.

Link: https://lore.kernel.org/all/20250702111908.03759998@batman.local.home/

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Link: https://lore.kernel.org/20250702143657.18dd1882@batman.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 include/linux/trace_events.h |  3 ---
 kernel/trace/trace_events.c  | 24 ++++++++++++------------
 2 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index fa9cf4292dff..04307a19cde3 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -480,7 +480,6 @@ enum {
 	EVENT_FILE_FL_RECORDED_TGID_BIT,
 	EVENT_FILE_FL_FILTERED_BIT,
 	EVENT_FILE_FL_NO_SET_FILTER_BIT,
-	EVENT_FILE_FL_SOFT_MODE_BIT,
 	EVENT_FILE_FL_SOFT_DISABLED_BIT,
 	EVENT_FILE_FL_TRIGGER_MODE_BIT,
 	EVENT_FILE_FL_TRIGGER_COND_BIT,
@@ -618,7 +617,6 @@ extern int __kprobe_event_add_fields(struct dynevent_cmd *cmd, ...);
  *  RECORDED_TGID - The tgids should be recorded at sched_switch
  *  FILTERED	  - The event has a filter attached
  *  NO_SET_FILTER - Set when filter has error and is to be ignored
- *  SOFT_MODE     - The event is enabled/disabled by SOFT_DISABLED
  *  SOFT_DISABLED - When set, do not trace the event (even though its
  *                   tracepoint may be enabled)
  *  TRIGGER_MODE  - When set, invoke the triggers associated with the event
@@ -633,7 +631,6 @@ enum {
 	EVENT_FILE_FL_RECORDED_TGID	= (1 << EVENT_FILE_FL_RECORDED_TGID_BIT),
 	EVENT_FILE_FL_FILTERED		= (1 << EVENT_FILE_FL_FILTERED_BIT),
 	EVENT_FILE_FL_NO_SET_FILTER	= (1 << EVENT_FILE_FL_NO_SET_FILTER_BIT),
-	EVENT_FILE_FL_SOFT_MODE		= (1 << EVENT_FILE_FL_SOFT_MODE_BIT),
 	EVENT_FILE_FL_SOFT_DISABLED	= (1 << EVENT_FILE_FL_SOFT_DISABLED_BIT),
 	EVENT_FILE_FL_TRIGGER_MODE	= (1 << EVENT_FILE_FL_TRIGGER_MODE_BIT),
 	EVENT_FILE_FL_TRIGGER_COND	= (1 << EVENT_FILE_FL_TRIGGER_COND_BIT),
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 120531268abf..0980f4def360 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -768,6 +768,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 {
 	struct trace_event_call *call = file->event_call;
 	struct trace_array *tr = file->tr;
+	bool soft_mode = atomic_read(&file->sm_ref) != 0;
 	int ret = 0;
 	int disable;
 
@@ -782,7 +783,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		 * is set we do not want the event to be enabled before we
 		 * clear the bit.
 		 *
-		 * When soft_disable is not set but the SOFT_MODE flag is,
+		 * When soft_disable is not set but the soft_mode is,
 		 * we do nothing. Do not disable the tracepoint, otherwise
 		 * "soft enable"s (clearing the SOFT_DISABLED bit) wont work.
 		 */
@@ -790,11 +791,11 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 			if (atomic_dec_return(&file->sm_ref) > 0)
 				break;
 			disable = file->flags & EVENT_FILE_FL_SOFT_DISABLED;
-			clear_bit(EVENT_FILE_FL_SOFT_MODE_BIT, &file->flags);
+			soft_mode = false;
 			/* Disable use of trace_buffered_event */
 			trace_buffered_event_disable();
 		} else
-			disable = !(file->flags & EVENT_FILE_FL_SOFT_MODE);
+			disable = !soft_mode;
 
 		if (disable && (file->flags & EVENT_FILE_FL_ENABLED)) {
 			clear_bit(EVENT_FILE_FL_ENABLED_BIT, &file->flags);
@@ -812,8 +813,8 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 
 			WARN_ON_ONCE(ret);
 		}
-		/* If in SOFT_MODE, just set the SOFT_DISABLE_BIT, else clear it */
-		if (file->flags & EVENT_FILE_FL_SOFT_MODE)
+		/* If in soft mode, just set the SOFT_DISABLE_BIT, else clear it */
+		if (soft_mode)
 			set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
 		else
 			clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
@@ -823,7 +824,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		 * When soft_disable is set and enable is set, we want to
 		 * register the tracepoint for the event, but leave the event
 		 * as is. That means, if the event was already enabled, we do
-		 * nothing (but set SOFT_MODE). If the event is disabled, we
+		 * nothing (but set soft_mode). If the event is disabled, we
 		 * set SOFT_DISABLED before enabling the event tracepoint, so
 		 * it still seems to be disabled.
 		 */
@@ -832,7 +833,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		else {
 			if (atomic_inc_return(&file->sm_ref) > 1)
 				break;
-			set_bit(EVENT_FILE_FL_SOFT_MODE_BIT, &file->flags);
+			soft_mode = true;
 			/* Enable use of trace_buffered_event */
 			trace_buffered_event_enable();
 		}
@@ -840,7 +841,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		if (!(file->flags & EVENT_FILE_FL_ENABLED)) {
 			bool cmd = false, tgid = false;
 
-			/* Keep the event disabled, when going to SOFT_MODE. */
+			/* Keep the event disabled, when going to soft mode. */
 			if (soft_disable)
 				set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
 
@@ -1792,8 +1793,7 @@ event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
 	    !(flags & EVENT_FILE_FL_SOFT_DISABLED))
 		strcpy(buf, "1");
 
-	if (flags & EVENT_FILE_FL_SOFT_DISABLED ||
-	    flags & EVENT_FILE_FL_SOFT_MODE)
+	if (atomic_read(&file->sm_ref) != 0)
 		strcat(buf, "*");
 
 	strcat(buf, "\n");
@@ -3584,7 +3584,7 @@ static int probe_remove_event_call(struct trace_event_call *call)
 			continue;
 		/*
 		 * We can't rely on ftrace_event_enable_disable(enable => 0)
-		 * we are going to do, EVENT_FILE_FL_SOFT_MODE can suppress
+		 * we are going to do, soft mode can suppress
 		 * TRACE_REG_UNREGISTER.
 		 */
 		if (file->flags & EVENT_FILE_FL_ENABLED)
@@ -3997,7 +3997,7 @@ static int free_probe_data(void *data)
 
 	edata->ref--;
 	if (!edata->ref) {
-		/* Remove the SOFT_MODE flag */
+		/* Remove soft mode */
 		__ftrace_event_enable_disable(edata->file, 0, 1);
 		trace_event_put_ref(edata->file->event_call);
 		kfree(edata);
-- 
2.47.2

[for-next][PATCH 7/8] tracing: Fix comment in trace_module_remove_events()

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

Fix typo "allocade" -> "allocated".

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250710095628.42ed6b06@batman.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_events.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 0980f4def360..6c0783fc4c2c 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -3695,7 +3695,7 @@ static void trace_module_remove_events(struct module *mod)
 		if (call->module == mod)
 			__trace_remove_event_call(call);
 	}
-	/* Check for any strings allocade for this module */
+	/* Check for any strings allocated for this module */
 	list_for_each_entry_safe(modstr, m, &module_strings, next) {
 		if (modstr->module != mod)
 			continue;
-- 
2.47.2

[for-next][PATCH 8/8] tracing: Deprecate auto-mounting tracefs in debugfs

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

In January 2015, tracefs was created to allow access to the tracing
infrastructure without needing to compile in debugfs. When tracefs is
configured, the directory /sys/kernel/tracing will exist and tooling is
expected to use that path to access the tracing infrastructure.

To allow backward compatibility, when debugfs is mounted, it would
automount tracefs in its "tracing" directory so that tooling that had hard
coded /sys/kernel/debug/tracing would still work.

It has been over 10 years since the new interface was introduced, and all
tooling should now be using it. Start the process of deprecating the old
path so that it doesn't need to be maintained anymore.

A new config is added to allow distributions to disable automounting of
tracefs on debugfs.

If /sys/kernel/debug/tracing is accessed, a pr_warn() will trigger stating:

"NOTICE: Automounting of tracing to debugfs is deprecated and will be removed in 2030"

Expect to remove this feature in 5 years (2030).

Cc: <linux-trace-users@vger.kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/20250722170806.40c068c6@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 .../ABI/obsolete/automount-tracefs-debugfs    | 20 +++++++++++++++++++
 kernel/trace/Kconfig                          | 13 ++++++++++++
 kernel/trace/trace.c                          | 14 +++++++++----
 3 files changed, 43 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/ABI/obsolete/automount-tracefs-debugfs

diff --git a/Documentation/ABI/obsolete/automount-tracefs-debugfs b/Documentation/ABI/obsolete/automount-tracefs-debugfs
new file mode 100644
index 000000000000..a5196ec78cb5
--- /dev/null
+++ b/Documentation/ABI/obsolete/automount-tracefs-debugfs
@@ -0,0 +1,20 @@
+What:		/sys/kernel/debug/tracing
+Date:		May 2008
+KernelVersion:	2.6.27
+Contact:	linux-trace-kernel@vger.kernel.org
+Description:
+
+	The ftrace was first added to the kernel, its interface was placed
+	into the debugfs file system under the "tracing" directory. Access
+	to the files were in /sys/kernel/debug/tracing. As systems wanted
+	access to the tracing interface without having to enable debugfs, a
+	new interface was created called "tracefs". This was a stand alone
+	file system and was usually mounted in /sys/kernel/tracing.
+
+	To allow older tooling to continue to operate, when mounting
+	debugfs, the tracefs file system would automatically get mounted in
+	the "tracing" directory of debugfs. The tracefs interface was added
+	in January 2015 in the v4.1 kernel.
+
+	All tooling should now be using tracefs directly and the "tracing"
+	directory in debugfs should be removed by January 2030.
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index a3f35c7d83b6..93e8e7fc11c0 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -199,6 +199,19 @@ menuconfig FTRACE
 
 if FTRACE
 
+config TRACEFS_AUTOMOUNT_DEPRECATED
+	bool "Automount tracefs on debugfs [DEPRECATED]"
+	depends on TRACING
+	default y
+	help
+	  The tracing interface was moved from /sys/kernel/debug/tracing
+	  to /sys/kernel/tracing in 2015, but the tracing file system
+	  was still automounted in /sys/kernel/debug for backward
+	  compatibility with tooling.
+
+	  The new interface has been around for more than 10 years and
+	  the old debug mount will soon be removed.
+
 config BOOTTIME_TRACING
 	bool "Boot-time Tracing support"
 	depends on TRACING
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0dff4298fc0e..06ab5b7a8711 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6296,7 +6296,7 @@ static bool tracer_options_updated;
 static void add_tracer_options(struct trace_array *tr, struct tracer *t)
 {
 	/* Only enable if the directory has been created already. */
-	if (!tr->dir)
+	if (!tr->dir && !(tr->flags & TRACE_ARRAY_FL_GLOBAL))
 		return;
 
 	/* Only create trace option files after update_tracer_options finish */
@@ -8977,13 +8977,13 @@ static inline __init int register_snapshot_cmd(void) { return 0; }
 
 static struct dentry *tracing_get_dentry(struct trace_array *tr)
 {
-	if (WARN_ON(!tr->dir))
-		return ERR_PTR(-ENODEV);
-
 	/* Top directory uses NULL as the parent */
 	if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
 		return NULL;
 
+	if (WARN_ON(!tr->dir))
+		return ERR_PTR(-ENODEV);
+
 	/* All sub buffers have a descriptor */
 	return tr->dir;
 }
@@ -10249,6 +10249,7 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 	ftrace_init_tracefs(tr, d_tracer);
 }
 
+#ifdef CONFIG_TRACEFS_AUTOMOUNT_DEPRECATED
 static struct vfsmount *trace_automount(struct dentry *mntpt, void *ingore)
 {
 	struct vfsmount *mnt;
@@ -10270,6 +10271,8 @@ static struct vfsmount *trace_automount(struct dentry *mntpt, void *ingore)
 	if (IS_ERR(fc))
 		return ERR_CAST(fc);
 
+	pr_warn("NOTICE: Automounting of tracing to debugfs is deprecated and will be removed in 2030\n");
+
 	ret = vfs_parse_fs_string(fc, "source",
 				  "tracefs", strlen("tracefs"));
 	if (!ret)
@@ -10280,6 +10283,7 @@ static struct vfsmount *trace_automount(struct dentry *mntpt, void *ingore)
 	put_fs_context(fc);
 	return mnt;
 }
+#endif
 
 /**
  * tracing_init_dentry - initialize top level trace array
@@ -10304,6 +10308,7 @@ int tracing_init_dentry(void)
 	if (WARN_ON(!tracefs_initialized()))
 		return -ENODEV;
 
+#ifdef CONFIG_TRACEFS_AUTOMOUNT_DEPRECATED
 	/*
 	 * As there may still be users that expect the tracing
 	 * files to exist in debugfs/tracing, we must automount
@@ -10312,6 +10317,7 @@ int tracing_init_dentry(void)
 	 */
 	tr->dir = debugfs_create_automount("tracing", NULL,
 					   trace_automount, NULL);
+#endif
 
 	return 0;
 }
-- 
2.47.2