linux/kernel/trace/trace_boot.c
Arnaldo Carvalho de Melo 51a763dd84 tracing: Introduce trace_buffer_{lock_reserve,unlock_commit}
Impact: new API

These new functions do what previously was being open coded, reducing
the number of details ftrace plugin writers have to worry about.

It also standardizes the handling of stacktrace, userstacktrace and
other trace options we may introduce in the future.

With this patch, for instance, the blk tracer (and some others already
in the tree) can use the "userstacktrace" /d/tracing/trace_options
facility.

$ codiff /tmp/vmlinux.before /tmp/vmlinux.after
linux-2.6-tip/kernel/trace/trace.c:
  trace_vprintk              |   -5
  trace_graph_return         |  -22
  trace_graph_entry          |  -26
  trace_function             |  -45
  __ftrace_trace_stack       |  -27
  ftrace_trace_userstack     |  -29
  tracing_sched_switch_trace |  -66
  tracing_stop               |   +1
  trace_seq_to_user          |   -1
  ftrace_trace_special       |  -63
  ftrace_special             |   +1
  tracing_sched_wakeup_trace |  -70
  tracing_reset_online_cpus  |   -1
 13 functions changed, 2 bytes added, 355 bytes removed, diff: -353

linux-2.6-tip/block/blktrace.c:
  __blk_add_trace |  -58
 1 function changed, 58 bytes removed, diff: -58

linux-2.6-tip/kernel/trace/trace.c:
  trace_buffer_lock_reserve  |  +88
  trace_buffer_unlock_commit |  +86
 2 functions changed, 174 bytes added, diff: +174

/tmp/vmlinux.after:
 16 functions changed, 176 bytes added, 413 bytes removed, diff: -237

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Frédéric Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-06 01:01:41 +01:00

179 lines
3.8 KiB
C

/*
* ring buffer based initcalls tracer
*
* Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>
*
*/
#include <linux/init.h>
#include <linux/debugfs.h>
#include <linux/ftrace.h>
#include <linux/kallsyms.h>
#include "trace.h"
#include "trace_output.h"
static struct trace_array *boot_trace;
static bool pre_initcalls_finished;
/* Tells the boot tracer that the pre_smp_initcalls are finished.
* So we are ready .
* It doesn't enable sched events tracing however.
* You have to call enable_boot_trace to do so.
*/
void start_boot_trace(void)
{
pre_initcalls_finished = true;
}
void enable_boot_trace(void)
{
if (boot_trace && pre_initcalls_finished)
tracing_start_sched_switch_record();
}
void disable_boot_trace(void)
{
if (boot_trace && pre_initcalls_finished)
tracing_stop_sched_switch_record();
}
static int boot_trace_init(struct trace_array *tr)
{
int cpu;
boot_trace = tr;
if (!tr)
return 0;
for_each_cpu(cpu, cpu_possible_mask)
tracing_reset(tr, cpu);
tracing_sched_switch_assign_trace(tr);
return 0;
}
static enum print_line_t
initcall_call_print_line(struct trace_iterator *iter)
{
struct trace_entry *entry = iter->ent;
struct trace_seq *s = &iter->seq;
struct trace_boot_call *field;
struct boot_trace_call *call;
u64 ts;
unsigned long nsec_rem;
int ret;
trace_assign_type(field, entry);
call = &field->boot_call;
ts = iter->ts;
nsec_rem = do_div(ts, 1000000000);
ret = trace_seq_printf(s, "[%5ld.%09ld] calling %s @ %i\n",
(unsigned long)ts, nsec_rem, call->func, call->caller);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
else
return TRACE_TYPE_HANDLED;
}
static enum print_line_t
initcall_ret_print_line(struct trace_iterator *iter)
{
struct trace_entry *entry = iter->ent;
struct trace_seq *s = &iter->seq;
struct trace_boot_ret *field;
struct boot_trace_ret *init_ret;
u64 ts;
unsigned long nsec_rem;
int ret;
trace_assign_type(field, entry);
init_ret = &field->boot_ret;
ts = iter->ts;
nsec_rem = do_div(ts, 1000000000);
ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s "
"returned %d after %llu msecs\n",
(unsigned long) ts,
nsec_rem,
init_ret->func, init_ret->result, init_ret->duration);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
else
return TRACE_TYPE_HANDLED;
}
static enum print_line_t initcall_print_line(struct trace_iterator *iter)
{
struct trace_entry *entry = iter->ent;
switch (entry->type) {
case TRACE_BOOT_CALL:
return initcall_call_print_line(iter);
case TRACE_BOOT_RET:
return initcall_ret_print_line(iter);
default:
return TRACE_TYPE_UNHANDLED;
}
}
struct tracer boot_tracer __read_mostly =
{
.name = "initcall",
.init = boot_trace_init,
.reset = tracing_reset_online_cpus,
.print_line = initcall_print_line,
};
void trace_boot_call(struct boot_trace_call *bt, initcall_t fn)
{
struct ring_buffer_event *event;
struct trace_boot_call *entry;
struct trace_array *tr = boot_trace;
if (!tr || !pre_initcalls_finished)
return;
/* Get its name now since this function could
* disappear because it is in the .init section.
*/
sprint_symbol(bt->func, (unsigned long)fn);
preempt_disable();
event = trace_buffer_lock_reserve(tr, TRACE_BOOT_CALL,
sizeof(*entry), 0, 0);
if (!event)
goto out;
entry = ring_buffer_event_data(event);
entry->boot_call = *bt;
trace_buffer_unlock_commit(tr, event, 0, 0);
out:
preempt_enable();
}
void trace_boot_ret(struct boot_trace_ret *bt, initcall_t fn)
{
struct ring_buffer_event *event;
struct trace_boot_ret *entry;
struct trace_array *tr = boot_trace;
if (!tr || !pre_initcalls_finished)
return;
sprint_symbol(bt->func, (unsigned long)fn);
preempt_disable();
event = trace_buffer_lock_reserve(tr, TRACE_BOOT_RET,
sizeof(*entry), 0, 0);
if (!event)
goto out;
entry = ring_buffer_event_data(event);
entry->boot_ret = *bt;
trace_buffer_unlock_commit(tr, event, 0, 0);
out:
preempt_enable();
}