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tracing: Enable comm recording if trace_printk() is used

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If comm recording is not enabled when trace_printk() is used then
you just get this type of output:

[ adding trace_printk("hello! %d", irq); in do_IRQ ]

           <...>-2843  [001] d.h.    80.812300: do_IRQ: hello! 14
           <...>-2734  [002] d.h2    80.824664: do_IRQ: hello! 14
           <...>-2713  [003] d.h.    80.829971: do_IRQ: hello! 14
           <...>-2814  [000] d.h.    80.833026: do_IRQ: hello! 14

By enabling the comm recorder when trace_printk is enabled:

       hackbench-6715  [001] d.h.   193.233776: do_IRQ: hello! 21
            sshd-2659  [001] d.h.   193.665862: do_IRQ: hello! 21
          <idle>-0     [001] d.h1   193.665996: do_IRQ: hello! 21

Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2012-10-11 10:15:05 -04:00 committed by Steven Rostedt
parent b382ede6b5
commit 81698831bc
3 changed files with 38 additions and 2 deletions
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36
kernel/trace/trace.c
View File

@ -1559,10 +1559,10 @@ static int alloc_percpu_trace_buffer(void)
return -ENOMEM;
}
static int buffers_allocated;
void trace_printk_init_buffers(void)
{
static int buffers_allocated;
if (buffers_allocated)
return;
@ -1575,6 +1575,34 @@ void trace_printk_init_buffers(void)
tracing_update_buffers();
buffers_allocated = 1;
/*
* trace_printk_init_buffers() can be called by modules.
* If that happens, then we need to start cmdline recording
* directly here. If the global_trace.buffer is already
* allocated here, then this was called by module code.
*/
if (global_trace.buffer)
tracing_start_cmdline_record();
}
void trace_printk_start_comm(void)
{
/* Start tracing comms if trace printk is set */
if (!buffers_allocated)
return;
tracing_start_cmdline_record();
}
static void trace_printk_start_stop_comm(int enabled)
{
if (!buffers_allocated)
return;
if (enabled)
tracing_start_cmdline_record();
else
tracing_stop_cmdline_record();
}
/**
@ -2797,6 +2825,9 @@ static void set_tracer_flags(unsigned int mask, int enabled)
if (mask == TRACE_ITER_OVERWRITE)
ring_buffer_change_overwrite(global_trace.buffer, enabled);
if (mask == TRACE_ITER_PRINTK)
trace_printk_start_stop_comm(enabled);
}
static ssize_t
@ -5099,6 +5130,7 @@ __init static int tracer_alloc_buffers(void)
/* Only allocate trace_printk buffers if a trace_printk exists */
if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt)
/* Must be called before global_trace.buffer is allocated */
trace_printk_init_buffers();
/* To save memory, keep the ring buffer size to its minimum */

1
kernel/trace/trace.h
View File

@ -841,6 +841,7 @@ extern const char *__start___trace_bprintk_fmt[];
extern const char *__stop___trace_bprintk_fmt[];
void trace_printk_init_buffers(void);
void trace_printk_start_comm(void);
#undef FTRACE_ENTRY
#define FTRACE_ENTRY(call, struct_name, id, tstruct, print, filter) \

3
kernel/trace/trace_events.c
View File

@ -1489,6 +1489,9 @@ static __init int event_trace_enable(void)
if (ret)
pr_warn("Failed to enable trace event: %s\n", token);
}
trace_printk_start_comm();
return 0;
}