From: "Steven Rostedt (VMware)" Allow writing to the trace_markers file initiate triggers defined in tracefs/ftrace/print/trigger file. This will allow of user space to trigger the same type of triggers (including histograms) that the trace events use. Had to create a ftrace_event_register() function that will become the trace_marker print event's reg() function. This is required because of how triggers are enabled: event_trigger_write() { event_trigger_regex_write() { trigger_process_regex() { for p in trigger_commands { p->func(); /* trigger_snapshot_cmd->func */ event_trigger_callback() { cmd_ops->reg() /* register_trigger() */ { trace_event_trigger_enable_disable() { trace_event_enable_disable() { call->class->reg(); Without the reg() function, the trigger code will call a NULL pointer and crash the system. Cc: Tom Zanussi Cc: Clark Williams Cc: Karim Yaghmour Cc: Brendan Gregg Suggested-by: Joel Fernandes Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace.c | 17 +++++++++++++++++ kernel/trace/trace.h | 1 + kernel/trace/trace_entries.h | 6 ++++-- kernel/trace/trace_export.c | 7 +++++++ 4 files changed, 29 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index e0d6ffb76985..f11b89fa5049 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6074,6 +6074,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, { struct trace_array *tr = filp->private_data; struct ring_buffer_event *event; + enum event_trigger_type tt = ETT_NONE; struct ring_buffer *buffer; struct print_entry *entry; unsigned long irq_flags; @@ -6122,6 +6123,12 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, written = cnt; len = cnt; + if (tr->trace_marker_file && !list_empty(&tr->trace_marker_file->triggers)) { + /* do not add \n before testing triggers, but add \0 */ + entry->buf[cnt] = '\0'; + tt = event_triggers_call(tr->trace_marker_file, entry, event); + } + if (entry->buf[cnt - 1] != '\n') { entry->buf[cnt] = '\n'; entry->buf[cnt + 1] = '\0'; @@ -6130,6 +6137,9 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, __buffer_unlock_commit(buffer, event); + if (tt) + event_triggers_post_call(tr->trace_marker_file, tt); + if (written > 0) *fpos += written; @@ -7896,6 +7906,7 @@ static __init void create_trace_instances(struct dentry *d_tracer) static void init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer) { + struct trace_event_file *file; int cpu; trace_create_file("available_tracers", 0444, d_tracer, @@ -7928,6 +7939,12 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer) trace_create_file("trace_marker", 0220, d_tracer, tr, &tracing_mark_fops); + file = __find_event_file(tr, "ftrace", "print"); + if (file && file->dir) + trace_create_file("trigger", 0644, file->dir, file, + &event_trigger_fops); + tr->trace_marker_file = file; + trace_create_file("trace_marker_raw", 0220, d_tracer, tr, &tracing_mark_raw_fops); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 2414fd72dedd..c7fa58d31a84 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -259,6 +259,7 @@ struct trace_array { struct trace_options *topts; struct list_head systems; struct list_head events; + struct trace_event_file *trace_marker_file; cpumask_var_t tracing_cpumask; /* only trace on set CPUs */ int ref; #ifdef CONFIG_FUNCTION_TRACER diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h index e3a658bac10f..1d67464ed95e 100644 --- a/kernel/trace/trace_entries.h +++ b/kernel/trace/trace_entries.h @@ -230,7 +230,7 @@ FTRACE_ENTRY(bprint, bprint_entry, FILTER_OTHER ); -FTRACE_ENTRY(print, print_entry, +FTRACE_ENTRY_REG(print, print_entry, TRACE_PRINT, @@ -242,7 +242,9 @@ FTRACE_ENTRY(print, print_entry, F_printk("%ps: %s", (void *)__entry->ip, __entry->buf), - FILTER_OTHER + FILTER_OTHER, + + ftrace_event_register ); FTRACE_ENTRY(raw_data, raw_data_entry, diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c index d842f1eadfe5..45630a76ed3a 100644 --- a/kernel/trace/trace_export.c +++ b/kernel/trace/trace_export.c @@ -14,6 +14,13 @@ #include "trace_output.h" +/* Stub function for events with triggers */ +static int ftrace_event_register(struct trace_event_call *call, + enum trace_reg type, void *data) +{ + return 0; +} + #undef TRACE_SYSTEM #define TRACE_SYSTEM ftrace -- 2.17.0