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trace: let boot trace be chosen by command line 

Now that we have a working ftrace=<tracer> function, make the boot
tracer get activated by it. This way we can turn it on or off without
recompiling the kernel, as well as keeping the selftests on. The
selftests are disabled whenever a default tracer starts running.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt 2009-02-02 21:38:33 -05:00 committed by Ingo Molnar
parent b2821ae68b
commit 79fb0768fb
3 changed files with 11 additions and 12 deletions
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7
kernel/trace/Kconfig
View File

@ -164,9 +164,8 @@ config BOOT_TRACER
representation of the delays during initcalls - but the raw representation of the delays during initcalls - but the raw
/debug/tracing/trace text output is readable too. /debug/tracing/trace text output is readable too.
( Note that tracing self tests can't be enabled if this tracer is You must pass in ftrace=initcall to the kernel command line
selected, because the self-tests are an initcall as well and that to enable this on bootup.
would invalidate the boot trace. )
config TRACE_BRANCH_PROFILING config TRACE_BRANCH_PROFILING
bool "Trace likely/unlikely profiler" bool "Trace likely/unlikely profiler"
@ -326,7 +325,7 @@ config FTRACE_SELFTEST
config FTRACE_STARTUP_TEST config FTRACE_STARTUP_TEST
bool "Perform a startup test on ftrace" bool "Perform a startup test on ftrace"
depends on TRACING && DEBUG_KERNEL && !BOOT_TRACER depends on TRACING && DEBUG_KERNEL
select FTRACE_SELFTEST select FTRACE_SELFTEST
help help
This option performs a series of startup tests on ftrace. On bootup This option performs a series of startup tests on ftrace. On bootup

5
kernel/trace/trace.c
View File

@ -3167,12 +3167,9 @@ __init static int tracer_alloc_buffers(void)
trace_init_cmdlines(); trace_init_cmdlines();
register_tracer(&nop_trace); register_tracer(&nop_trace);
current_trace = &nop_trace;
#ifdef CONFIG_BOOT_TRACER #ifdef CONFIG_BOOT_TRACER
register_tracer(&boot_tracer); register_tracer(&boot_tracer);
current_trace = &boot_tracer;
current_trace->init(&global_trace);
#else
current_trace = &nop_trace;
#endif #endif
/* All seems OK, enable tracing */ /* All seems OK, enable tracing */
tracing_disabled = 0; tracing_disabled = 0;

11
kernel/trace/trace_boot.c
View File

@ -28,13 +28,13 @@ void start_boot_trace(void)
void enable_boot_trace(void) void enable_boot_trace(void)
{ {
if (pre_initcalls_finished) if (boot_trace && pre_initcalls_finished)
tracing_start_sched_switch_record(); tracing_start_sched_switch_record();
} }
void disable_boot_trace(void) void disable_boot_trace(void)
{ {
if (pre_initcalls_finished) if (boot_trace && pre_initcalls_finished)
tracing_stop_sched_switch_record(); tracing_stop_sched_switch_record();
} }
@ -43,6 +43,9 @@ static int boot_trace_init(struct trace_array *tr)
int cpu; int cpu;
boot_trace = tr; boot_trace = tr;
if (!tr)
return 0;
for_each_cpu(cpu, cpu_possible_mask) for_each_cpu(cpu, cpu_possible_mask)
tracing_reset(tr, cpu); tracing_reset(tr, cpu);
@ -132,7 +135,7 @@ void trace_boot_call(struct boot_trace_call *bt, initcall_t fn)
unsigned long irq_flags; unsigned long irq_flags;
struct trace_array *tr = boot_trace; struct trace_array *tr = boot_trace;
if (!pre_initcalls_finished) if (!tr || !pre_initcalls_finished)
return; return;
/* Get its name now since this function could /* Get its name now since this function could
@ -164,7 +167,7 @@ void trace_boot_ret(struct boot_trace_ret *bt, initcall_t fn)
unsigned long irq_flags; unsigned long irq_flags;
struct trace_array *tr = boot_trace; struct trace_array *tr = boot_trace;
if (!pre_initcalls_finished) if (!tr || !pre_initcalls_finished)
return; return;
sprint_symbol(bt->func, (unsigned long)fn); sprint_symbol(bt->func, (unsigned long)fn);