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: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 98524d0656bfc4d69ce00bd7e53c1b659ddebf1b..40521216667737f6891db3916ad248d0d372660e 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -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))

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index b50383aa8e5022e460e573ca9ed4077af7e70fa6..ebb47abc0ee7fba482edc140703186fd33ad047c 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -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);