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tracing/ftrace: change the type of the print_line callback
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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: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Frederic Weisbecker authored and Ingo Molnar committed Oct 14, 2008
1 parent 777e208 commit 2c4f035
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Showing 2 changed files with 50 additions and 37 deletions.
77 changes: 41 additions & 36 deletions kernel/trace/trace.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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)
Expand Down Expand Up @@ -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);
Expand All @@ -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);

Expand All @@ -1386,38 +1386,38 @@ 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: {
struct ftrace_entry *field = (struct ftrace_entry *)entry;

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
ret = seq_print_ip_sym(s,
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:
Expand All @@ -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: {
Expand All @@ -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: {
Expand All @@ -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: {
Expand All @@ -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;
Expand All @@ -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: {
Expand All @@ -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:
Expand All @@ -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:
Expand All @@ -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: {
Expand All @@ -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) \
Expand All @@ -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';
Expand All @@ -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);
Expand Down Expand Up @@ -1628,18 +1628,18 @@ 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;

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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
Expand Down
10 changes: 9 additions & 1 deletion kernel/trace/trace.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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:
*/
Expand All @@ -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;
};
Expand Down

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