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Commit 0438cf86 authored by Jamie Gennis's avatar Jamie Gennis Committed by Ruchi Kandoi
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trace: Add an option to show tgids in trace output 



The tgids are tracked along side the saved_cmdlines tracking, and can be
included in trace output by enabling the 'print-tgid' trace option. This is
useful when doing post-processing of the trace data, as it allows events to be
grouped by tgid.

Change-Id: I52ed04c3a8ca7fddbb868b792ce5d21ceb76250e
Signed-off-by: default avatarJamie Gennis <jgennis@google.com>
parent 1058a5ce

kernel/trace/trace.c

+96 −3
Original line number Diff line number Diff line
@@ -812,6 +812,7 @@ static const char *trace_options[] = { 
	"irq-info",

	"markers",

	"function-trace",

	"print-tgid",

	NULL

};
@@ -1279,6 +1280,7 @@ void tracing_reset_all_online_cpus(void) 


#define SAVED_CMDLINES_DEFAULT 128

#define NO_CMDLINE_MAP UINT_MAX

static unsigned saved_tgids[SAVED_CMDLINES];

static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;

struct saved_cmdlines_buffer {

	unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
@@ -1517,7 +1519,7 @@ static int trace_save_cmdline(struct task_struct *tsk) 
	}



	set_cmdline(idx, tsk->comm);



	saved_tgids[idx] = tsk->tgid;

	arch_spin_unlock(&trace_cmdline_lock);



	return 1;
@@ -1560,6 +1562,25 @@ void trace_find_cmdline(int pid, char comm[]) 
	preempt_enable();

}



int trace_find_tgid(int pid)

{

	unsigned map;

	int tgid;



	preempt_disable();

	arch_spin_lock(&trace_cmdline_lock);

	map = map_pid_to_cmdline[pid];

	if (map != NO_CMDLINE_MAP)

		tgid = saved_tgids[map];

	else

		tgid = -1;



	arch_spin_unlock(&trace_cmdline_lock);

	preempt_enable();



	return tgid;

}



void tracing_record_cmdline(struct task_struct *tsk)

{

	if (atomic_read(&trace_record_cmdline_disabled) || !tracing_is_on())
@@ -2537,6 +2558,13 @@ static void print_func_help_header(struct trace_buffer *buf, struct seq_file *m) 
	seq_puts(m, "#              | |       |          |         |\n");

}



static void print_func_help_header_tgid(struct trace_buffer *buf, struct seq_file *m)

{

	print_event_info(buf, m);

	seq_puts(m, "#           TASK-PID    TGID   CPU#      TIMESTAMP  FUNCTION\n");

	seq_puts(m, "#              | |        |      |          |         |\n");

}



static void print_func_help_header_irq(struct trace_buffer *buf, struct seq_file *m)

{

	print_event_info(buf, m);
@@ -2549,6 +2577,18 @@ static void print_func_help_header_irq(struct trace_buffer *buf, struct seq_file 
	seq_puts(m, "#              | |       |   ||||       |         |\n");

}



static void print_func_help_header_irq_tgid(struct trace_buffer *buf, struct seq_file *m)

{

	print_event_info(buf, m);

	seq_puts(m, "#                                      _-----=> irqs-off\n");

	seq_puts(m, "#                                     / _----=> need-resched\n");

	seq_puts(m, "#                                    | / _---=> hardirq/softirq\n");

	seq_puts(m, "#                                    || / _--=> preempt-depth\n");

	seq_puts(m, "#                                    ||| /     delay\n");

	seq_puts(m, "#           TASK-PID    TGID   CPU#  ||||    TIMESTAMP  FUNCTION\n");

	seq_puts(m, "#              | |        |      |   ||||       |         |\n");

}



void

print_trace_header(struct seq_file *m, struct trace_iterator *iter)

{
@@ -2849,7 +2889,13 @@ void trace_default_header(struct seq_file *m) 
	} else {

		if (!(trace_flags & TRACE_ITER_VERBOSE)) {

			if (trace_flags & TRACE_ITER_IRQ_INFO)

				if (trace_flags & TRACE_ITER_TGID)

					print_func_help_header_irq_tgid(iter->trace_buffer, m);

				else

					print_func_help_header_irq(iter->trace_buffer, m);

			else

				if (trace_flags & TRACE_ITER_TGID)

					print_func_help_header_tgid(iter->trace_buffer, m);

				else

					print_func_help_header(iter->trace_buffer, m);

		}
@@ -3896,6 +3942,50 @@ static const struct file_operations tracing_saved_cmdlines_size_fops = { 
	.write		= tracing_saved_cmdlines_size_write,

};



static ssize_t

tracing_saved_tgids_read(struct file *file, char __user *ubuf,

				size_t cnt, loff_t *ppos)

{

	char *file_buf;

	char *buf;

	int len = 0;

	int pid;

	int i;



	file_buf = kmalloc(SAVED_CMDLINES*(16+1+16), GFP_KERNEL);

	if (!file_buf)

		return -ENOMEM;



	buf = file_buf;



	for (i = 0; i < SAVED_CMDLINES; i++) {

		int tgid;

		int r;



		pid = map_cmdline_to_pid[i];

		if (pid == -1 || pid == NO_CMDLINE_MAP)

			continue;



		tgid = trace_find_tgid(pid);

		r = sprintf(buf, "%d %d\n", pid, tgid);

		buf += r;

		len += r;

	}



	len = simple_read_from_buffer(ubuf, cnt, ppos,

				      file_buf, len);



	kfree(file_buf);



	return len;

}



static const struct file_operations tracing_saved_tgids_fops = {

	.open	= tracing_open_generic,

	.read	= tracing_saved_tgids_read,

	.llseek	= generic_file_llseek,

};



static ssize_t

tracing_set_trace_read(struct file *filp, char __user *ubuf,

		       size_t cnt, loff_t *ppos)
@@ -6520,6 +6610,9 @@ init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer) 
	trace_create_file("trace_marker", 0220, d_tracer,

			  tr, &tracing_mark_fops);



	trace_create_file("saved_tgids", 0444, d_tracer,

			  tr, &tracing_saved_tgids_fops);



	trace_create_file("trace_clock", 0644, d_tracer, tr,

			  &trace_clock_fops);

kernel/trace/trace.h

+2 −0
Original line number Diff line number Diff line
@@ -658,6 +658,7 @@ static inline void __trace_stack(struct trace_array *tr, unsigned long flags, 
extern cycle_t ftrace_now(int cpu);



extern void trace_find_cmdline(int pid, char comm[]);

extern int trace_find_tgid(int pid);



#ifdef CONFIG_DYNAMIC_FTRACE

extern unsigned long ftrace_update_tot_cnt;
@@ -938,6 +939,7 @@ enum trace_iterator_flags { 
	TRACE_ITER_IRQ_INFO		= 0x800000,

	TRACE_ITER_MARKERS		= 0x1000000,

	TRACE_ITER_FUNCTION		= 0x2000000,

	TRACE_ITER_TGID 		= 0x4000000,

};



/*

kernel/trace/trace_output.c

+16 −2
Original line number Diff line number Diff line
@@ -521,11 +521,25 @@ int trace_print_context(struct trace_iterator *iter) 
	unsigned long secs, usec_rem;

	char comm[TASK_COMM_LEN];

	int ret;

	int tgid;



	trace_find_cmdline(entry->pid, comm);



	ret = trace_seq_printf(s, "%16s-%-5d [%03d] ",

			       comm, entry->pid, iter->cpu);

	ret = trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);

	if (!ret)

		return 0;



	if (trace_flags & TRACE_ITER_TGID) {

		tgid = trace_find_tgid(entry->pid);

		if (tgid < 0)

			ret = trace_seq_puts(s, "(-----) ");

		else

			ret = trace_seq_printf(s, "(%5d) ", tgid);

		if (!ret)

			return 0;

	}



	ret = trace_seq_printf(s, "[%03d] ", iter->cpu);

	if (!ret)

		return 0;