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Commit 53d0aa77 authored by Steven Rostedt's avatar Steven Rostedt Committed by Thomas Gleixner
Browse files

ftrace: add logic to record overruns 



This patch sets up the infrastructure to record overruns of the tracing
buffer.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 72b59d67

kernel/trace/trace.c

+11 −5
Original line number Diff line number Diff line
@@ -609,6 +609,7 @@ void unregister_tracer(struct tracer *type) 
void tracing_reset(struct trace_array_cpu *data)

{

	data->trace_idx = 0;

	data->overrun = 0;

	data->trace_head = data->trace_tail = head_page(data);

	data->trace_head_idx = 0;

	data->trace_tail_idx = 0;
@@ -750,6 +751,7 @@ tracing_get_trace_entry(struct trace_array *tr, struct trace_array_cpu *data) 
	if (data->trace_head == data->trace_tail &&

	    idx_next == data->trace_tail_idx) {

		/* overrun */

		data->overrun++;

		data->trace_tail_idx++;

		if (data->trace_tail_idx >= ENTRIES_PER_PAGE) {

			data->trace_tail =
@@ -2353,8 +2355,6 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 
{

	struct trace_iterator *iter = filp->private_data;

	struct trace_array_cpu *data;

	struct trace_array *tr = iter->tr;

	struct tracer *tracer = iter->trace;

	static cpumask_t mask;

	static int start;

	unsigned long flags;
@@ -2433,10 +2433,11 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 
	if (cnt >= PAGE_SIZE)

		cnt = PAGE_SIZE - 1;



	memset(iter, 0, sizeof(*iter));

	iter->tr = tr;

	iter->trace = tracer;

	/* reset all but tr, trace, and overruns */

	iter->pos = -1;

	memset(&iter->seq, 0,

	       sizeof(struct trace_iterator) -

	       offsetof(struct trace_iterator, seq));



	/*

	 * We need to stop all tracing on all CPUS to read the
@@ -2465,6 +2466,11 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 
	for_each_cpu_mask(cpu, mask) {

		data = iter->tr->data[cpu];

		__raw_spin_lock(&data->lock);



		if (data->overrun > iter->last_overrun[cpu])

			iter->overrun[cpu] +=

				data->overrun - iter->last_overrun[cpu];

		iter->last_overrun[cpu] = data->overrun;

	}



	while (find_next_entry_inc(iter) != NULL) {

kernel/trace/trace.h

+5 −1
Original line number Diff line number Diff line
@@ -97,6 +97,7 @@ struct trace_array_cpu { 
	void			*trace_head; /* producer */

	void			*trace_tail; /* consumer */

	unsigned long		trace_idx;

	unsigned long		overrun;

	unsigned long		saved_latency;

	unsigned long		critical_start;

	unsigned long		critical_end;
@@ -157,10 +158,13 @@ struct trace_seq { 
 * results to users and which routines might sleep, etc:

 */

struct trace_iterator {

	struct trace_seq	seq;

	struct trace_array	*tr;

	struct tracer		*trace;

	long			last_overrun[NR_CPUS];

	long			overrun[NR_CPUS];



	/* The below is zeroed out in pipe_read */

	struct trace_seq	seq;

	struct trace_entry	*ent;

	int			cpu;