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Commit 2c4f035f authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
Browse files

tracing/ftrace: change the type of the print_line callback 



We need a kind of disambiguation when a print_line callback
returns 0.

_There is not enough space to print all the entry.
 Please flush the seq and retry.
_I can't handle this type of entry

This patch changes the type of this callback for better information.

Also some changes have been made in this V2.

_ Only relay to default functions after the print_line callback fails.
_ This patch doesn't fix the issue with the broken pipe (see patch 2/4 for that)

Some things are still in discussion:

_ Find better names for the enum print_line_t values
_ Change the type of print_trace_line into boolean.

Patches to change that can be sent later.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarPekka Paalanen <pq@iki.fi>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 777e208d

kernel/trace/trace.c

+41 −36
Original line number Diff line number Diff line
@@ -1250,7 +1250,7 @@ void trace_seq_print_cont(struct trace_seq *s, struct trace_iterator *iter) 
		trace_seq_putc(s, '\n');

}



static int

static enum print_line_t

print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)

{

	struct trace_seq *s = &iter->seq;
@@ -1267,7 +1267,7 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu) 
	unsigned state;



	if (entry->type == TRACE_CONT)

		return 1;

		return TRACE_TYPE_HANDLED;



	next_entry = find_next_entry(iter, NULL, &next_ts);

	if (!next_entry)
@@ -1357,10 +1357,10 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu) 
	default:

		trace_seq_printf(s, "Unknown type %d\n", entry->type);

	}

	return 1;

	return TRACE_TYPE_HANDLED;

}



static int print_trace_fmt(struct trace_iterator *iter)

static enum print_line_t print_trace_fmt(struct trace_iterator *iter)

{

	struct trace_seq *s = &iter->seq;

	unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
@@ -1376,7 +1376,7 @@ static int print_trace_fmt(struct trace_iterator *iter) 
	entry = iter->ent;



	if (entry->type == TRACE_CONT)

		return 1;

		return TRACE_TYPE_HANDLED;



	comm = trace_find_cmdline(iter->ent->pid);
@@ -1386,13 +1386,13 @@ static int print_trace_fmt(struct trace_iterator *iter) 


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

	if (!ret)

		return 0;

		return TRACE_TYPE_PARTIAL_LINE;

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

	if (!ret)

		return 0;

		return TRACE_TYPE_PARTIAL_LINE;

	ret = trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem);

	if (!ret)

		return 0;

		return TRACE_TYPE_PARTIAL_LINE;



	switch (entry->type) {

	case TRACE_FN: {
@@ -1400,12 +1400,12 @@ static int print_trace_fmt(struct trace_iterator *iter) 


		ret = seq_print_ip_sym(s, field->ip, sym_flags);

		if (!ret)

			return 0;

			return TRACE_TYPE_PARTIAL_LINE;

		if ((sym_flags & TRACE_ITER_PRINT_PARENT) &&

						field->parent_ip) {

			ret = trace_seq_printf(s, " <-");

			if (!ret)

				return 0;

				return TRACE_TYPE_PARTIAL_LINE;

			if (kretprobed(field->parent_ip))

				ret = trace_seq_puts(s, KRETPROBE_MSG);

			else
@@ -1413,11 +1413,11 @@ static int print_trace_fmt(struct trace_iterator *iter) 
						       field->parent_ip,

						       sym_flags);

			if (!ret)

				return 0;

				return TRACE_TYPE_PARTIAL_LINE;

		}

		ret = trace_seq_printf(s, "\n");

		if (!ret)

			return 0;

			return TRACE_TYPE_PARTIAL_LINE;

		break;

	}

	case TRACE_CTX:
@@ -1439,7 +1439,7 @@ static int print_trace_fmt(struct trace_iterator *iter) 
				       field->next_prio,

				       T);

		if (!ret)

			return 0;

			return TRACE_TYPE_PARTIAL_LINE;

		break;

	}

	case TRACE_SPECIAL: {
@@ -1450,7 +1450,7 @@ static int print_trace_fmt(struct trace_iterator *iter) 
				 field->arg2,

				 field->arg3);

		if (!ret)

			return 0;

			return TRACE_TYPE_PARTIAL_LINE;

		break;

	}

	case TRACE_STACK: {
@@ -1460,16 +1460,16 @@ static int print_trace_fmt(struct trace_iterator *iter) 
			if (i) {

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

				if (!ret)

					return 0;

					return TRACE_TYPE_PARTIAL_LINE;

			}

			ret = seq_print_ip_sym(s, field->caller[i],

					       sym_flags);

			if (!ret)

				return 0;

				return TRACE_TYPE_PARTIAL_LINE;

		}

		ret = trace_seq_puts(s, "\n");

		if (!ret)

			return 0;

			return TRACE_TYPE_PARTIAL_LINE;

		break;

	}

	case TRACE_PRINT: {
@@ -1482,10 +1482,10 @@ static int print_trace_fmt(struct trace_iterator *iter) 
		break;

	}

	}

	return 1;

	return TRACE_TYPE_HANDLED;

}



static int print_raw_fmt(struct trace_iterator *iter)

static enum print_line_t print_raw_fmt(struct trace_iterator *iter)

{

	struct trace_seq *s = &iter->seq;

	struct trace_entry *entry;
@@ -1495,12 +1495,12 @@ static int print_raw_fmt(struct trace_iterator *iter) 
	entry = iter->ent;



	if (entry->type == TRACE_CONT)

		return 1;

		return TRACE_TYPE_HANDLED;



	ret = trace_seq_printf(s, "%d %d %llu ",

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

	if (!ret)

		return 0;

		return TRACE_TYPE_PARTIAL_LINE;



	switch (entry->type) {

	case TRACE_FN: {
@@ -1510,7 +1510,7 @@ static int print_raw_fmt(struct trace_iterator *iter) 
					field->ip,

					field->parent_ip);

		if (!ret)

			return 0;

			return TRACE_TYPE_PARTIAL_LINE;

		break;

	}

	case TRACE_CTX:
@@ -1533,7 +1533,7 @@ static int print_raw_fmt(struct trace_iterator *iter) 
				       field->next_prio,

				       T);

		if (!ret)

			return 0;

			return TRACE_TYPE_PARTIAL_LINE;

		break;

	}

	case TRACE_SPECIAL:
@@ -1545,7 +1545,7 @@ static int print_raw_fmt(struct trace_iterator *iter) 
				 field->arg2,

				 field->arg3);

		if (!ret)

			return 0;

			return TRACE_TYPE_PARTIAL_LINE;

		break;

	}

	case TRACE_PRINT: {
@@ -1557,7 +1557,7 @@ static int print_raw_fmt(struct trace_iterator *iter) 
		break;

	}

	}

	return 1;

	return TRACE_TYPE_HANDLED;

}



#define SEQ_PUT_FIELD_RET(s, x)				\
@@ -1572,7 +1572,7 @@ do { \ 
		return 0;				\

} while (0)



static int print_hex_fmt(struct trace_iterator *iter)

static enum print_line_t print_hex_fmt(struct trace_iterator *iter)

{

	struct trace_seq *s = &iter->seq;

	unsigned char newline = '\n';
@@ -1582,7 +1582,7 @@ static int print_hex_fmt(struct trace_iterator *iter) 
	entry = iter->ent;



	if (entry->type == TRACE_CONT)

		return 1;

		return TRACE_TYPE_HANDLED;



	SEQ_PUT_HEX_FIELD_RET(s, entry->pid);

	SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
@@ -1628,10 +1628,10 @@ static int print_hex_fmt(struct trace_iterator *iter) 
	}

	SEQ_PUT_FIELD_RET(s, newline);



	return 1;

	return TRACE_TYPE_HANDLED;

}



static int print_bin_fmt(struct trace_iterator *iter)

static enum print_line_t print_bin_fmt(struct trace_iterator *iter)

{

	struct trace_seq *s = &iter->seq;

	struct trace_entry *entry;
@@ -1639,7 +1639,7 @@ static int print_bin_fmt(struct trace_iterator *iter) 
	entry = iter->ent;



	if (entry->type == TRACE_CONT)

		return 1;

		return TRACE_TYPE_HANDLED;



	SEQ_PUT_FIELD_RET(s, entry->pid);

	SEQ_PUT_FIELD_RET(s, iter->cpu);
@@ -1686,13 +1686,18 @@ static int trace_empty(struct trace_iterator *iter) 
		if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))

			return 0;

	}

	return 1;

	return TRACE_TYPE_HANDLED;

}



static int print_trace_line(struct trace_iterator *iter)

static enum print_line_t print_trace_line(struct trace_iterator *iter)

{

	if (iter->trace && iter->trace->print_line)

		return iter->trace->print_line(iter);

	enum print_line_t ret;



	if (iter->trace && iter->trace->print_line) {

		ret = iter->trace->print_line(iter);

		if (ret != TRACE_TYPE_UNHANDLED)

			return ret;

	}



	if (trace_flags & TRACE_ITER_BIN)

		return print_bin_fmt(iter);
@@ -2525,11 +2530,11 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 
	ring_buffer_lock(iter->tr->buffer, &flags);



	while (find_next_entry_inc(iter) != NULL) {

		int ret;

		enum print_line_t ret;

		int len = iter->seq.len;



		ret = print_trace_line(iter);

		if (!ret) {

		if (ret == TRACE_TYPE_PARTIAL_LINE) {

			/* don't print partial lines */

			iter->seq.len = len;

			break;

kernel/trace/trace.h

+9 −1
Original line number Diff line number Diff line
@@ -177,6 +177,14 @@ struct trace_array { 
	struct trace_array_cpu	*data[NR_CPUS];

};





/* Return values for print_line callback */

enum print_line_t {

	TRACE_TYPE_PARTIAL_LINE	= 0,	/* Retry after flushing the seq */

	TRACE_TYPE_HANDLED	= 1,

	TRACE_TYPE_UNHANDLED	= 2	/* Relay to other output functions */

};



/*

 * A specific tracer, represented by methods that operate on a trace array:

 */
@@ -197,7 +205,7 @@ struct tracer { 
	int			(*selftest)(struct tracer *trace,

					    struct trace_array *tr);

#endif

	int			(*print_line)(struct trace_iterator *iter);

	enum print_line_t	(*print_line)(struct trace_iterator *iter);

	struct tracer		*next;

	int			print_max;

};