tracing/osnoise: Array printk init and cleanup

None of the calls to trace_array_printk_buf() will do anything
if we don't initialize the buffer on instance creation (unless
some other tracer called it), so do that.

Add an osnoise_print() function to facilitate adding debug prints
(without tainting).

Use trace_array_printk() instead of trace_array_printk_buf(), as we're
only writing to the main buffer (of a non-main instance) anyway -- and
trace_array_printk_buf() skips the check to make sure we're not printing
to the global instance.

Link: https://patch.msgid.link/20260511223035.1475676-1-crwood@redhat.com
Signed-off-by: Crystal Wood <crwood@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 62c2667d97fa96aab407ade900492f13e4db0635..5e83c4f6f2b429c432ddf6ff387ac7426c615b83 100644 (file)
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -83,6 +83,22 @@ struct osnoise_instance {
 
 static struct list_head osnoise_instances;
 
+static void osnoise_print(const char *fmt, ...)
+{
+       struct osnoise_instance *inst;
+       struct trace_array *tr;
+       va_list ap;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(inst, &osnoise_instances, list) {
+               tr = inst->tr;
+               va_start(ap, fmt);
+               trace_array_vprintk(tr, _RET_IP_, fmt, ap);
+               va_end(ap);
+       }
+       rcu_read_unlock();
+}
+
 static bool osnoise_has_registered_instances(void)
 {
        return !!list_first_or_null_rcu(&osnoise_instances,
@@ -123,6 +139,7 @@ static int osnoise_register_instance(struct trace_array *tr)
         * trace_types_lock.
         */
        lockdep_assert_held(&trace_types_lock);
+       trace_array_init_printk(tr);
 
        inst = kmalloc_obj(*inst);
        if (!inst)
@@ -471,15 +488,7 @@ static void print_osnoise_headers(struct seq_file *s)
  * osnoise_taint - report an osnoise error.
  */
 #define osnoise_taint(msg) ({                                                  \
-       struct osnoise_instance *inst;                                          \
-       struct trace_buffer *buffer;                                            \
-                                                                               \
-       rcu_read_lock();                                                        \
-       list_for_each_entry_rcu(inst, &osnoise_instances, list) {               \
-               buffer = inst->tr->array_buffer.buffer;                         \
-               trace_array_printk_buf(buffer, _THIS_IP_, msg);                 \
-       }                                                                       \
-       rcu_read_unlock();                                                      \
+       osnoise_print(msg);                                                     \
        osnoise_data.tainted = true;                                            \
 })
 
@@ -1189,10 +1198,10 @@ static __always_inline void osnoise_stop_exception(char *msg, int cpu)
        rcu_read_lock();
        list_for_each_entry_rcu(inst, &osnoise_instances, list) {
                tr = inst->tr;
-               trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_,
-                                      "stop tracing hit on cpu %d due to exception: %s\n",
-                                      smp_processor_id(),
-                                      msg);
+               trace_array_printk(tr, _THIS_IP_,
+                                  "stop tracing hit on cpu %d due to exception: %s\n",
+                                  smp_processor_id(),
+                                  msg);
 
                if (test_bit(OSN_PANIC_ON_STOP, &osnoise_options))
                        panic("tracer hit on cpu %d due to exception: %s\n",
@@ -1362,8 +1371,8 @@ static __always_inline void osnoise_stop_tracing(void)
        rcu_read_lock();
        list_for_each_entry_rcu(inst, &osnoise_instances, list) {
                tr = inst->tr;
-               trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_,
-                               "stop tracing hit on cpu %d\n", smp_processor_id());
+               trace_array_printk(tr, _THIS_IP_,
+                                  "stop tracing hit on cpu %d\n", smp_processor_id());
 
                if (test_bit(OSN_PANIC_ON_STOP, &osnoise_options))
                        panic("tracer hit stop condition on CPU %d\n", smp_processor_id());