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Date: Fri, 26 Sep 2008 17:25:21 +0200
From: Frederic Weisbecker <fweisbec@...il.com>
To: mingo@...e.hu
CC: rostedt@...dmis.org, linux-kernel@...r.kernel.org, pq@....fi
Subject: [Path -tip 1/3] Tracing/ftrace: Change the type of the print_line
callback
We need a kind of disambiguation when a print_line callback returns 0.
This value can significate both:
_ There is not enough space to print all of the entry. Please flush the current seq and retry
_ I can't handle this type of entry.
Such a confusion can break the pipe.
This patch changes the type of this callback for a better information.
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index b28bf88..73cd7c5 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -180,6 +180,14 @@ 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:
*/
@@ -200,7 +208,7 @@ 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;
};
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 50ac334..ca95ec3 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1510,7 +1510,7 @@ 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;
@@ -1530,7 +1530,7 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
next_entry = entry;
if (entry->type == TRACE_CONT)
- return 1;
+ return TRACE_TYPE_HANDLED;
rel_usecs = ns2usecs(next_entry->field.t - entry->field.t);
abs_usecs = ns2usecs(entry->field.t - iter->tr->time_start);
@@ -1601,10 +1601,10 @@ 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);
@@ -1621,7 +1621,7 @@ static int print_trace_fmt(struct trace_iterator *iter)
entry = iter->ent;
if (entry->type == TRACE_CONT)
- return 1;
+ return TRACE_TYPE_HANDLED;
field = &entry->field;
@@ -1633,24 +1633,24 @@ static int print_trace_fmt(struct trace_iterator *iter)
ret = trace_seq_printf(s, "%16s-%-5d ", comm, field->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:
ret = seq_print_ip_sym(s, field->fn.ip, sym_flags);
if (!ret)
- return 0;
+ return TRACE_TYPE_PARTIAL_LINE;
if ((sym_flags & TRACE_ITER_PRINT_PARENT) &&
field->fn.parent_ip) {
ret = trace_seq_printf(s, " <-");
if (!ret)
- return 0;
+ return TRACE_TYPE_PARTIAL_LINE;
if (kretprobed(field->fn.parent_ip))
ret = trace_seq_puts(s, KRETPROBE_MSG);
else
@@ -1658,11 +1658,11 @@ static int print_trace_fmt(struct trace_iterator *iter)
field->fn.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:
case TRACE_WAKE:
@@ -1680,7 +1680,7 @@ static int print_trace_fmt(struct trace_iterator *iter)
field->ctx.next_prio,
T);
if (!ret)
- return 0;
+ return TRACE_TYPE_PARTIAL_LINE;
break;
case TRACE_SPECIAL:
ret = trace_seq_printf(s, "# %ld %ld %ld\n",
@@ -1688,23 +1688,23 @@ static int print_trace_fmt(struct trace_iterator *iter)
field->special.arg2,
field->special.arg3);
if (!ret)
- return 0;
+ return TRACE_TYPE_PARTIAL_LINE;
break;
case TRACE_STACK:
for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
if (i) {
ret = trace_seq_puts(s, " <= ");
if (!ret)
- return 0;
+ return TRACE_TYPE_PARTIAL_LINE;
}
ret = seq_print_ip_sym(s, field->stack.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:
seq_print_ip_sym(s, field->print.ip, sym_flags);
@@ -1713,10 +1713,10 @@ static int print_trace_fmt(struct trace_iterator *iter)
trace_seq_print_cont(s, 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;
@@ -1727,14 +1727,14 @@ static int print_raw_fmt(struct trace_iterator *iter)
entry = iter->ent;
if (entry->type == TRACE_CONT)
- return 1;
+ return TRACE_TYPE_HANDLED;
field = &entry->field;
ret = trace_seq_printf(s, "%d %d %llu ",
field->pid, iter->cpu, field->t);
if (!ret)
- return 0;
+ return TRACE_TYPE_PARTIAL_LINE;
switch (entry->type) {
case TRACE_FN:
@@ -1742,7 +1742,7 @@ static int print_raw_fmt(struct trace_iterator *iter)
field->fn.ip,
field->fn.parent_ip);
if (!ret)
- return 0;
+ return TRACE_TYPE_PARTIAL_LINE;
break;
case TRACE_CTX:
case TRACE_WAKE:
@@ -1761,7 +1761,7 @@ static int print_raw_fmt(struct trace_iterator *iter)
field->ctx.next_prio,
T);
if (!ret)
- return 0;
+ return TRACE_TYPE_PARTIAL_LINE;
break;
case TRACE_SPECIAL:
case TRACE_STACK:
@@ -1770,7 +1770,7 @@ static int print_raw_fmt(struct trace_iterator *iter)
field->special.arg2,
field->special.arg3);
if (!ret)
- return 0;
+ return TRACE_TYPE_PARTIAL_LINE;
break;
case TRACE_PRINT:
trace_seq_printf(s, "# %lx %s",
@@ -1779,7 +1779,7 @@ static int print_raw_fmt(struct trace_iterator *iter)
trace_seq_print_cont(s, iter);
break;
}
- return 1;
+ return TRACE_TYPE_HANDLED;
}
#define SEQ_PUT_FIELD_RET(s, x) \
@@ -1794,7 +1794,7 @@ 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';
@@ -1805,7 +1805,7 @@ static int print_hex_fmt(struct trace_iterator *iter)
entry = iter->ent;
if (entry->type == TRACE_CONT)
- return 1;
+ return TRACE_TYPE_HANDLED;
field = &entry->field;
@@ -1843,10 +1843,10 @@ 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;
@@ -1855,7 +1855,7 @@ static int print_bin_fmt(struct trace_iterator *iter)
entry = iter->ent;
if (entry->type == TRACE_CONT)
- return 1;
+ return TRACE_TYPE_HANDLED;
field = &entry->field;
@@ -1883,7 +1883,7 @@ static int print_bin_fmt(struct trace_iterator *iter)
SEQ_PUT_FIELD_RET(s, field->special.arg3);
break;
}
- return 1;
+ return TRACE_TYPE_HANDLED;
}
static int trace_empty(struct trace_iterator *iter)
@@ -1904,27 +1904,42 @@ static int trace_empty(struct trace_iterator *iter)
static int print_trace_line(struct trace_iterator *iter)
{
- int ret;
+ enum print_line_t ret;
- if (iter->trace && iter->trace->print_line)
- if ((ret = iter->trace->print_line(iter)))
+ if (iter->trace && iter->trace->print_line) {
+ ret = iter->trace->print_line(iter);
+ if (ret == TRACE_TYPE_HANDLED ||
+ ret == TRACE_TYPE_PARTIAL_LINE)
return ret;
+ }
- if (trace_flags & TRACE_ITER_BIN)
- if ((ret = print_bin_fmt(iter)))
+ if (trace_flags & TRACE_ITER_BIN) {
+ ret = print_bin_fmt(iter);
+ if (ret == TRACE_TYPE_HANDLED ||
+ ret == TRACE_TYPE_PARTIAL_LINE)
return ret;
+ }
- if (trace_flags & TRACE_ITER_HEX)
- if ((ret = print_hex_fmt(iter)))
+ if (trace_flags & TRACE_ITER_HEX) {
+ ret = print_hex_fmt(iter);
+ if (ret == TRACE_TYPE_HANDLED ||
+ ret == TRACE_TYPE_PARTIAL_LINE)
return ret;
+ }
- if (trace_flags & TRACE_ITER_RAW)
- if ((ret = print_raw_fmt(iter)))
+ if (trace_flags & TRACE_ITER_RAW) {
+ ret = print_raw_fmt(iter);
+ if (ret == TRACE_TYPE_HANDLED ||
+ ret == TRACE_TYPE_PARTIAL_LINE)
return ret;
+ }
- if (iter->iter_flags & TRACE_FILE_LAT_FMT)
- if ((ret = print_lat_fmt(iter, iter->idx, iter->cpu)))
+ if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
+ ret = print_lat_fmt(iter, iter->idx, iter->cpu);
+ if (ret == TRACE_TYPE_HANDLED ||
+ ret == TRACE_TYPE_PARTIAL_LINE)
return ret;
+ }
return print_trace_fmt(iter);
}
@@ -2722,11 +2737,11 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
}
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;
@@ -2738,6 +2753,10 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
break;
}
+ if (!iter->seq.len)
+ /* Don't break the pipe */
+ trace_seq_puts(&iter->seq, "Warning: empty seq\n");
+
for_each_cpu_mask(cpu, mask) {
data = iter->tr->data[cpu];
__raw_spin_unlock(&data->lock);
--
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