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blktrace/tracing: Use trace_seq_has_overflowed() helper function
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Checking the return code of every trace_seq_printf() operation and having
to return early if it overflowed makes the code messy.

Using the new trace_seq_has_overflowed() and trace_handle_return() functions
allows us to clean up the code.

In the future, trace_seq_printf() and friends will be turning into void
functions and not returning a value. The trace_seq_has_overflowed() is to
be used instead. This cleanup allows that change to take place.

Cc: Jens Axboe <axboe@fb.com>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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@rostedt
rostedt committed Nov 19, 2014
1 parent 19a7fe2 commit f4a1d08
Showing 1 changed file with 66 additions and 82 deletions.
148 changes: 66 additions & 82 deletions kernel/trace/blktrace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1142,9 +1142,9 @@ static void get_pdu_remap(const struct trace_entry *ent,
r->sector_from = be64_to_cpu(sector_from);
}

typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act);

static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
static void blk_log_action_classic(struct trace_iterator *iter, const char *act)
{
char rwbs[RWBS_LEN];
unsigned long long ts = iter->ts;
Expand All @@ -1154,153 +1154,141 @@ static int blk_log_action_classic(struct trace_iterator *iter, const char *act)

fill_rwbs(rwbs, t);

return trace_seq_printf(&iter->seq,
"%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
MAJOR(t->device), MINOR(t->device), iter->cpu,
secs, nsec_rem, iter->ent->pid, act, rwbs);
trace_seq_printf(&iter->seq,
"%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
MAJOR(t->device), MINOR(t->device), iter->cpu,
secs, nsec_rem, iter->ent->pid, act, rwbs);
}

static int blk_log_action(struct trace_iterator *iter, const char *act)
static void blk_log_action(struct trace_iterator *iter, const char *act)
{
char rwbs[RWBS_LEN];
const struct blk_io_trace *t = te_blk_io_trace(iter->ent);

fill_rwbs(rwbs, t);
return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
MAJOR(t->device), MINOR(t->device), act, rwbs);
trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
MAJOR(t->device), MINOR(t->device), act, rwbs);
}

static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
static void blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
{
const unsigned char *pdu_buf;
int pdu_len;
int i, end, ret;
int i, end;

pdu_buf = pdu_start(ent);
pdu_len = te_blk_io_trace(ent)->pdu_len;

if (!pdu_len)
return 1;
return;

/* find the last zero that needs to be printed */
for (end = pdu_len - 1; end >= 0; end--)
if (pdu_buf[end])
break;
end++;

if (!trace_seq_putc(s, '('))
return 0;
trace_seq_putc(s, '(');

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

ret = trace_seq_printf(s, "%s%02x",
i == 0 ? "" : " ", pdu_buf[i]);
if (!ret)
return ret;
trace_seq_printf(s, "%s%02x",
i == 0 ? "" : " ", pdu_buf[i]);

/*
* stop when the rest is just zeroes and indicate so
* with a ".." appended
*/
if (i == end && end != pdu_len - 1)
return trace_seq_puts(s, " ..) ");
if (i == end && end != pdu_len - 1) {
trace_seq_puts(s, " ..) ");
return;
}
}

return trace_seq_puts(s, ") ");
trace_seq_puts(s, ") ");
}

static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
{
char cmd[TASK_COMM_LEN];

trace_find_cmdline(ent->pid, cmd);

if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
int ret;

ret = trace_seq_printf(s, "%u ", t_bytes(ent));
if (!ret)
return 0;
ret = blk_log_dump_pdu(s, ent);
if (!ret)
return 0;
return trace_seq_printf(s, "[%s]\n", cmd);
trace_seq_printf(s, "%u ", t_bytes(ent));
blk_log_dump_pdu(s, ent);
trace_seq_printf(s, "[%s]\n", cmd);
} else {
if (t_sec(ent))
return trace_seq_printf(s, "%llu + %u [%s]\n",
trace_seq_printf(s, "%llu + %u [%s]\n",
t_sector(ent), t_sec(ent), cmd);
return trace_seq_printf(s, "[%s]\n", cmd);
else
trace_seq_printf(s, "[%s]\n", cmd);
}
}

static int blk_log_with_error(struct trace_seq *s,
static void blk_log_with_error(struct trace_seq *s,
const struct trace_entry *ent)
{
if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
int ret;

ret = blk_log_dump_pdu(s, ent);
if (ret)
return trace_seq_printf(s, "[%d]\n", t_error(ent));
return 0;
blk_log_dump_pdu(s, ent);
trace_seq_printf(s, "[%d]\n", t_error(ent));
} else {
if (t_sec(ent))
return trace_seq_printf(s, "%llu + %u [%d]\n",
t_sector(ent),
t_sec(ent), t_error(ent));
return trace_seq_printf(s, "%llu [%d]\n",
t_sector(ent), t_error(ent));
trace_seq_printf(s, "%llu + %u [%d]\n",
t_sector(ent),
t_sec(ent), t_error(ent));
else
trace_seq_printf(s, "%llu [%d]\n",
t_sector(ent), t_error(ent));
}
}

static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
{
struct blk_io_trace_remap r = { .device_from = 0, };

get_pdu_remap(ent, &r);
return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
t_sector(ent), t_sec(ent),
MAJOR(r.device_from), MINOR(r.device_from),
(unsigned long long)r.sector_from);
trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
t_sector(ent), t_sec(ent),
MAJOR(r.device_from), MINOR(r.device_from),
(unsigned long long)r.sector_from);
}

static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
{
char cmd[TASK_COMM_LEN];

trace_find_cmdline(ent->pid, cmd);

return trace_seq_printf(s, "[%s]\n", cmd);
trace_seq_printf(s, "[%s]\n", cmd);
}

static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
{
char cmd[TASK_COMM_LEN];

trace_find_cmdline(ent->pid, cmd);

return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
}

static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
{
char cmd[TASK_COMM_LEN];

trace_find_cmdline(ent->pid, cmd);

return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
get_pdu_int(ent), cmd);
trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
get_pdu_int(ent), cmd);
}

static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
{
int ret;
const struct blk_io_trace *t = te_blk_io_trace(ent);

ret = trace_seq_putmem(s, t + 1, t->pdu_len);
if (ret)
return trace_seq_putc(s, '\n');
return ret;
trace_seq_putmem(s, t + 1, t->pdu_len);
trace_seq_putc(s, '\n');
}

/*
Expand Down Expand Up @@ -1339,7 +1327,7 @@ static void blk_tracer_reset(struct trace_array *tr)

static const struct {
const char *act[2];
int (*print)(struct trace_seq *s, const struct trace_entry *ent);
void (*print)(struct trace_seq *s, const struct trace_entry *ent);
} what2act[] = {
[__BLK_TA_QUEUE] = {{ "Q", "queue" }, blk_log_generic },
[__BLK_TA_BACKMERGE] = {{ "M", "backmerge" }, blk_log_generic },
Expand All @@ -1364,7 +1352,6 @@ static enum print_line_t print_one_line(struct trace_iterator *iter,
struct trace_seq *s = &iter->seq;
const struct blk_io_trace *t;
u16 what;
int ret;
bool long_act;
blk_log_action_t *log_action;

Expand All @@ -1374,21 +1361,18 @@ static enum print_line_t print_one_line(struct trace_iterator *iter,
log_action = classic ? &blk_log_action_classic : &blk_log_action;

if (t->action == BLK_TN_MESSAGE) {
ret = log_action(iter, long_act ? "message" : "m");
if (ret)
ret = blk_log_msg(s, iter->ent);
goto out;
log_action(iter, long_act ? "message" : "m");
blk_log_msg(s, iter->ent);
}

if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
ret = trace_seq_printf(s, "Unknown action %x\n", what);
trace_seq_printf(s, "Unknown action %x\n", what);
else {
ret = log_action(iter, what2act[what].act[long_act]);
if (ret)
ret = what2act[what].print(s, iter->ent);
log_action(iter, what2act[what].act[long_act]);
what2act[what].print(s, iter->ent);
}
out:
return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;

return trace_handle_return(s);
}

static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
Expand All @@ -1397,7 +1381,7 @@ static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
return print_one_line(iter, false);
}

static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
Expand All @@ -1407,18 +1391,18 @@ static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
.time = iter->ts,
};

if (!trace_seq_putmem(s, &old, offset))
return 0;
return trace_seq_putmem(s, &t->sector,
sizeof(old) - offset + t->pdu_len);
trace_seq_putmem(s, &old, offset);
trace_seq_putmem(s, &t->sector,
sizeof(old) - offset + t->pdu_len);
}

static enum print_line_t
blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
return blk_trace_synthesize_old_trace(iter) ?
TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
blk_trace_synthesize_old_trace(iter);

return trace_handle_return(&iter->seq);
}

static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
Expand Down

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