Commit e4c1a09a authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
Browse files

tracing: Add tracer_uses_snapshot() helper to remove #ifdefs 

Instead of having #ifdef CONFIG_TRACER_MAX_TRACE around every access to
the struct tracer's use_max_tr field, add a helper function for that
access and if CONFIG_TRACER_MAX_TRACE is not configured it just returns
false.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://patch.msgid.link/20260208183856.599390238@kernel.org


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 694b3f6f

kernel/trace/trace.c

+16 −35
Original line number Diff line number Diff line
@@ -810,7 +810,6 @@ EXPORT_SYMBOL_GPL(tracing_on); 
static void tracing_snapshot_instance_cond(struct trace_array *tr,

					   void *cond_data)

{

	struct tracer *tracer = tr->current_trace;

	unsigned long flags;



	if (in_nmi()) {
@@ -827,7 +826,7 @@ static void tracing_snapshot_instance_cond(struct trace_array *tr, 
	}



	/* Note, snapshot can not be used when the tracer uses it */

	if (tracer->use_max_tr) {

	if (tracer_uses_snapshot(tr->current_trace)) {

		trace_array_puts(tr, "*** LATENCY TRACER ACTIVE ***\n");

		trace_array_puts(tr, "*** Can not use snapshot (sorry) ***\n");

		return;
@@ -1076,7 +1075,7 @@ int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, 


	guard(mutex)(&trace_types_lock);



	if (tr->current_trace->use_max_tr)

	if (tracer_uses_snapshot(tr->current_trace))

		return -EBUSY;



	/*
@@ -1787,7 +1786,7 @@ static int run_tracer_selftest(struct tracer *type) 
	tr->current_trace_flags = type->flags ? : type->default_flags;



#ifdef CONFIG_TRACER_MAX_TRACE

	if (type->use_max_tr) {

	if (tracer_uses_snapshot(type)) {

		/* If we expanded the buffers, make sure the max is expanded too */

		if (tr->ring_buffer_expanded)

			ring_buffer_resize(tr->snapshot_buffer.buffer, trace_buf_size,
@@ -1812,7 +1811,7 @@ static int run_tracer_selftest(struct tracer *type) 
	tracing_reset_online_cpus(&tr->array_buffer);



#ifdef CONFIG_TRACER_MAX_TRACE

	if (type->use_max_tr) {

	if (tracer_uses_snapshot(type)) {

		tr->allocated_snapshot = false;



		/* Shrink the max buffer again */
@@ -3240,10 +3239,8 @@ static void *s_start(struct seq_file *m, loff_t *pos) 
	}

	mutex_unlock(&trace_types_lock);



#ifdef CONFIG_TRACER_MAX_TRACE

	if (iter->snapshot && iter->trace->use_max_tr)

	if (iter->snapshot && tracer_uses_snapshot(iter->trace))

		return ERR_PTR(-EBUSY);

#endif



	if (*pos != iter->pos) {

		iter->ent = NULL;
@@ -3282,10 +3279,8 @@ static void s_stop(struct seq_file *m, void *p) 
{

	struct trace_iterator *iter = m->private;



#ifdef CONFIG_TRACER_MAX_TRACE

	if (iter->snapshot && iter->trace->use_max_tr)

	if (iter->snapshot && tracer_uses_snapshot(iter->trace))

		return;

#endif



	trace_access_unlock(iter->cpu_file);

	trace_event_read_unlock();
@@ -4177,11 +4172,9 @@ static int tracing_open(struct inode *inode, struct file *file) 
static bool

trace_ok_for_array(struct tracer *t, struct trace_array *tr)

{

#ifdef CONFIG_TRACER_SNAPSHOT

	/* arrays with mapped buffer range do not have snapshots */

	if (tr->range_addr_start && t->use_max_tr)

	if (tr->range_addr_start && tracer_uses_snapshot(t))

		return false;

#endif

	return (tr->flags & TRACE_ARRAY_FL_GLOBAL) || t->allow_instances;

}
@@ -5550,9 +5543,7 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) 
{

	struct tracer *trace = NULL;

	struct tracers *t;

#ifdef CONFIG_TRACER_MAX_TRACE

	bool had_max_tr;

#endif

	int ret;



	guard(mutex)(&trace_types_lock);
@@ -5580,7 +5571,7 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) 
		return 0;



#ifdef CONFIG_TRACER_SNAPSHOT

	if (trace->use_max_tr) {

	if (tracer_uses_snapshot(trace)) {

		local_irq_disable();

		arch_spin_lock(&tr->max_lock);

		ret = tr->cond_snapshot ? -EBUSY : 0;
@@ -5612,14 +5603,13 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) 
	if (tr->current_trace->reset)

		tr->current_trace->reset(tr);



#ifdef CONFIG_TRACER_MAX_TRACE

	had_max_tr = tr->current_trace->use_max_tr;

	had_max_tr = tracer_uses_snapshot(tr->current_trace);



	/* Current trace needs to be nop_trace before synchronize_rcu */

	tr->current_trace = &nop_trace;

	tr->current_trace_flags = nop_trace.flags;



	if (had_max_tr && !trace->use_max_tr) {

	if (had_max_tr && !tracer_uses_snapshot(trace)) {

		/*

		 * We need to make sure that the update_max_tr sees that

		 * current_trace changed to nop_trace to keep it from
@@ -5632,24 +5622,19 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) 
		tracing_disarm_snapshot(tr);

	}



	if (!had_max_tr && trace->use_max_tr) {

	if (!had_max_tr && tracer_uses_snapshot(trace)) {

		ret = tracing_arm_snapshot_locked(tr);

		if (ret)

			return ret;

	}

#else

	tr->current_trace = &nop_trace;

#endif



	tr->current_trace_flags = t->flags ? : t->tracer->flags;



	if (trace->init) {

		ret = tracer_init(trace, tr);

		if (ret) {

#ifdef CONFIG_TRACER_MAX_TRACE

			if (trace->use_max_tr)

			if (tracer_uses_snapshot(trace))

				tracing_disarm_snapshot(tr);

#endif

			tr->current_trace_flags = nop_trace.flags;

			return ret;

		}
@@ -7207,7 +7192,7 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt, 


	guard(mutex)(&trace_types_lock);



	if (tr->current_trace->use_max_tr)

	if (tracer_uses_snapshot(tr->current_trace))

		return -EBUSY;



	local_irq_disable();
@@ -7306,7 +7291,7 @@ static int snapshot_raw_open(struct inode *inode, struct file *filp) 


	info = filp->private_data;



	if (info->iter.trace->use_max_tr) {

	if (tracer_uses_snapshot(info->iter.trace)) {

		tracing_buffers_release(inode, filp);

		return -EBUSY;

	}
@@ -7862,10 +7847,8 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, 
	if (!count)

		return 0;



#ifdef CONFIG_TRACER_MAX_TRACE

	if (iter->snapshot && iter->tr->current_trace->use_max_tr)

	if (iter->snapshot && tracer_uses_snapshot(iter->tr->current_trace))

		return -EBUSY;

#endif



	page_size = ring_buffer_subbuf_size_get(iter->array_buffer->buffer);
@@ -8049,10 +8032,8 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, 
	int entries, i;

	ssize_t ret = 0;



#ifdef CONFIG_TRACER_MAX_TRACE

	if (iter->snapshot && iter->tr->current_trace->use_max_tr)

	if (iter->snapshot && tracer_uses_snapshot(iter->tr->current_trace))

		return -EBUSY;

#endif



	page_size = ring_buffer_subbuf_size_get(iter->array_buffer->buffer);

	if (*ppos & (page_size - 1))

kernel/trace/trace.h

+12 −0
Original line number Diff line number Diff line
@@ -817,6 +817,18 @@ static inline void __trace_stack(struct trace_array *tr, unsigned int trace_ctx, 
}

#endif /* CONFIG_STACKTRACE */



#ifdef CONFIG_TRACER_MAX_TRACE

static inline bool tracer_uses_snapshot(struct tracer *tracer)

{

	return tracer->use_max_tr;

}

#else

static inline bool tracer_uses_snapshot(struct tracer *tracer)

{

	return false;

}

#endif



void trace_last_func_repeats(struct trace_array *tr,

			     struct trace_func_repeats *last_info,

			     unsigned int trace_ctx);