Re: [PATCH perf/core v4 01/19] perf probe: Use strbuf for making strings
From: Masami Hiramatsu
Date: Tue Apr 26 2016 - 10:40:57 EST
On Tue, 26 Apr 2016 10:36:57 -0300
Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
> Em Tue, Apr 26, 2016 at 06:02:11PM +0900, Masami Hiramatsu escreveu:
> > From: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> >
> > Replace many fixed-length char array with strbuf to
> > stringify perf_probe_event and probe_trace_event etc.
>
> Sure you want to do that? From time to time I try to reduce the strbuf
> usage, not grow it :-\
Aah, I got what you want.
>
> That is one of the last users of xrealloc(), via that ALLOC_GROW()
> thing.
Hmm I'm not sure what you considering, memory usage? or code reducing?
I also would like to remove e_snprintf() use in perf probe by replacing
with strbuf functions. I'd like to find better way.
Thank you,
>
> - Arnaldo
>
> > Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> > Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> >
> > ---
> > Changes in v4:
> > - Update for the latest kernel.
> > - Remove "probe-event.c" from title and body, because
> > this also changes probe-finder.c too :)
> >
> > Changes in v3:
> > - Remove unneeded strbuf_release(). (Thanks Namhyung!)
> >
> > Changes in v2:
> > - Make perf_probe_event__sprintf() simpler.
> > ---
> > tools/perf/util/probe-event.c | 246 ++++++++++++++--------------------------
> > tools/perf/util/probe-event.h | 2
> > tools/perf/util/probe-finder.c | 14 +-
> > 3 files changed, 93 insertions(+), 169 deletions(-)
> >
> > diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> > index 8319fbb..148af81 100644
> > --- a/tools/perf/util/probe-event.c
> > +++ b/tools/perf/util/probe-event.c
> > @@ -1618,69 +1618,51 @@ out:
> > }
> >
> > /* Compose only probe arg */
> > -int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf, size_t len)
> > +char *synthesize_perf_probe_arg(struct perf_probe_arg *pa)
> > {
> > struct perf_probe_arg_field *field = pa->field;
> > - int ret;
> > - char *tmp = buf;
> > + struct strbuf buf;
> > + char *ret;
> >
> > + strbuf_init(&buf, 64);
> > if (pa->name && pa->var)
> > - ret = e_snprintf(tmp, len, "%s=%s", pa->name, pa->var);
> > + strbuf_addf(&buf, "%s=%s", pa->name, pa->var);
> > else
> > - ret = e_snprintf(tmp, len, "%s", pa->name ? pa->name : pa->var);
> > - if (ret <= 0)
> > - goto error;
> > - tmp += ret;
> > - len -= ret;
> > + strbuf_addstr(&buf, pa->name ?: pa->var);
> >
> > while (field) {
> > if (field->name[0] == '[')
> > - ret = e_snprintf(tmp, len, "%s", field->name);
> > + strbuf_addstr(&buf, field->name);
> > else
> > - ret = e_snprintf(tmp, len, "%s%s",
> > - field->ref ? "->" : ".", field->name);
> > - if (ret <= 0)
> > - goto error;
> > - tmp += ret;
> > - len -= ret;
> > + strbuf_addf(&buf, "%s%s", field->ref ? "->" : ".",
> > + field->name);
> > field = field->next;
> > }
> >
> > - if (pa->type) {
> > - ret = e_snprintf(tmp, len, ":%s", pa->type);
> > - if (ret <= 0)
> > - goto error;
> > - tmp += ret;
> > - len -= ret;
> > - }
> > + if (pa->type)
> > + strbuf_addf(&buf, ":%s", pa->type);
> > +
> > + ret = strbuf_detach(&buf, NULL);
> >
> > - return tmp - buf;
> > -error:
> > - pr_debug("Failed to synthesize perf probe argument: %d\n", ret);
> > return ret;
> > }
> >
> > /* Compose only probe point (not argument) */
> > static char *synthesize_perf_probe_point(struct perf_probe_point *pp)
> > {
> > - char *buf, *tmp;
> > - char offs[32] = "", line[32] = "", file[32] = "";
> > - int ret, len;
> > -
> > - buf = zalloc(MAX_CMDLEN);
> > - if (buf == NULL) {
> > - ret = -ENOMEM;
> > - goto error;
> > - }
> > - if (pp->offset) {
> > - ret = e_snprintf(offs, 32, "+%lu", pp->offset);
> > - if (ret <= 0)
> > - goto error;
> > - }
> > - if (pp->line) {
> > - ret = e_snprintf(line, 32, ":%d", pp->line);
> > - if (ret <= 0)
> > - goto error;
> > + struct strbuf buf;
> > + char *tmp;
> > + int len;
> > +
> > + strbuf_init(&buf, 64);
> > + if (pp->function) {
> > + strbuf_addstr(&buf, pp->function);
> > + if (pp->offset)
> > + strbuf_addf(&buf, "+%lu", pp->offset);
> > + else if (pp->line)
> > + strbuf_addf(&buf, ":%d", pp->line);
> > + else if (pp->retprobe)
> > + strbuf_addstr(&buf, "%return");
> > }
> > if (pp->file) {
> > tmp = pp->file;
> > @@ -1689,25 +1671,12 @@ static char *synthesize_perf_probe_point(struct perf_probe_point *pp)
> > tmp = strchr(pp->file + len - 30, '/');
> > tmp = tmp ? tmp + 1 : pp->file + len - 30;
> > }
> > - ret = e_snprintf(file, 32, "@%s", tmp);
> > - if (ret <= 0)
> > - goto error;
> > + strbuf_addf(&buf, "@%s", tmp);
> > + if (!pp->function && pp->line)
> > + strbuf_addf(&buf, ":%d", pp->line);
> > }
> >
> > - if (pp->function)
> > - ret = e_snprintf(buf, MAX_CMDLEN, "%s%s%s%s%s", pp->function,
> > - offs, pp->retprobe ? "%return" : "", line,
> > - file);
> > - else
> > - ret = e_snprintf(buf, MAX_CMDLEN, "%s%s", file, line);
> > - if (ret <= 0)
> > - goto error;
> > -
> > - return buf;
> > -error:
> > - pr_debug("Failed to synthesize perf probe point: %d\n", ret);
> > - free(buf);
> > - return NULL;
> > + return strbuf_detach(&buf, NULL);
> > }
> >
> > #if 0
> > @@ -1736,45 +1705,30 @@ char *synthesize_perf_probe_command(struct perf_probe_event *pev)
> > #endif
> >
> > static int __synthesize_probe_trace_arg_ref(struct probe_trace_arg_ref *ref,
> > - char **buf, size_t *buflen,
> > - int depth)
> > + struct strbuf *buf, int depth)
> > {
> > - int ret;
> > if (ref->next) {
> > depth = __synthesize_probe_trace_arg_ref(ref->next, buf,
> > - buflen, depth + 1);
> > + depth + 1);
> > if (depth < 0)
> > goto out;
> > }
> > -
> > - ret = e_snprintf(*buf, *buflen, "%+ld(", ref->offset);
> > - if (ret < 0)
> > - depth = ret;
> > - else {
> > - *buf += ret;
> > - *buflen -= ret;
> > - }
> > + strbuf_addf(buf, "%+ld(", ref->offset);
> > out:
> > return depth;
> > -
> > }
> >
> > static int synthesize_probe_trace_arg(struct probe_trace_arg *arg,
> > - char *buf, size_t buflen)
> > + struct strbuf *buf)
> > {
> > struct probe_trace_arg_ref *ref = arg->ref;
> > - int ret, depth = 0;
> > - char *tmp = buf;
> > + int depth = 0;
> >
> > /* Argument name or separator */
> > if (arg->name)
> > - ret = e_snprintf(buf, buflen, " %s=", arg->name);
> > + strbuf_addf(buf, " %s=", arg->name);
> > else
> > - ret = e_snprintf(buf, buflen, " ");
> > - if (ret < 0)
> > - return ret;
> > - buf += ret;
> > - buflen -= ret;
> > + strbuf_addch(buf, ' ');
> >
> > /* Special case: @XXX */
> > if (arg->value[0] == '@' && arg->ref)
> > @@ -1782,60 +1736,41 @@ static int synthesize_probe_trace_arg(struct probe_trace_arg *arg,
> >
> > /* Dereferencing arguments */
> > if (ref) {
> > - depth = __synthesize_probe_trace_arg_ref(ref, &buf,
> > - &buflen, 1);
> > + depth = __synthesize_probe_trace_arg_ref(ref, buf, 1);
> > if (depth < 0)
> > return depth;
> > }
> >
> > /* Print argument value */
> > if (arg->value[0] == '@' && arg->ref)
> > - ret = e_snprintf(buf, buflen, "%s%+ld", arg->value,
> > - arg->ref->offset);
> > + strbuf_addf(buf, "%s%+ld", arg->value, arg->ref->offset);
> > else
> > - ret = e_snprintf(buf, buflen, "%s", arg->value);
> > - if (ret < 0)
> > - return ret;
> > - buf += ret;
> > - buflen -= ret;
> > + strbuf_addstr(buf, arg->value);
> >
> > /* Closing */
> > - while (depth--) {
> > - ret = e_snprintf(buf, buflen, ")");
> > - if (ret < 0)
> > - return ret;
> > - buf += ret;
> > - buflen -= ret;
> > - }
> > + while (depth--)
> > + strbuf_addch(buf, ')');
> > /* Print argument type */
> > - if (arg->type) {
> > - ret = e_snprintf(buf, buflen, ":%s", arg->type);
> > - if (ret <= 0)
> > - return ret;
> > - buf += ret;
> > - }
> > + if (arg->type)
> > + strbuf_addf(buf, ":%s", arg->type);
> >
> > - return buf - tmp;
> > + return 0;
> > }
> >
> > char *synthesize_probe_trace_command(struct probe_trace_event *tev)
> > {
> > struct probe_trace_point *tp = &tev->point;
> > - char *buf;
> > - int i, len, ret;
> > -
> > - buf = zalloc(MAX_CMDLEN);
> > - if (buf == NULL)
> > - return NULL;
> > -
> > - len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s ", tp->retprobe ? 'r' : 'p',
> > - tev->group, tev->event);
> > - if (len <= 0)
> > - goto error;
> > + struct strbuf buf;
> > + char *ret = NULL;
> > + int i;
> >
> > /* Uprobes must have tp->module */
> > if (tev->uprobes && !tp->module)
> > - goto error;
> > + return NULL;
> > +
> > + strbuf_init(&buf, 32);
> > + strbuf_addf(&buf, "%c:%s/%s ", tp->retprobe ? 'r' : 'p',
> > + tev->group, tev->event);
> > /*
> > * If tp->address == 0, then this point must be a
> > * absolute address uprobe.
> > @@ -1849,34 +1784,23 @@ char *synthesize_probe_trace_command(struct probe_trace_event *tev)
> >
> > /* Use the tp->address for uprobes */
> > if (tev->uprobes)
> > - ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s:0x%lx",
> > - tp->module, tp->address);
> > + strbuf_addf(&buf, "%s:0x%lx", tp->module, tp->address);
> > else if (!strncmp(tp->symbol, "0x", 2))
> > /* Absolute address. See try_to_find_absolute_address() */
> > - ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s%s0x%lx",
> > - tp->module ?: "", tp->module ? ":" : "",
> > - tp->address);
> > + strbuf_addf(&buf, "%s%s0x%lx", tp->module ?: "",
> > + tp->module ? ":" : "", tp->address);
> > else
> > - ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s%s%s+%lu",
> > - tp->module ?: "", tp->module ? ":" : "",
> > - tp->symbol, tp->offset);
> > -
> > - if (ret <= 0)
> > - goto error;
> > - len += ret;
> > + strbuf_addf(&buf, "%s%s%s+%lu", tp->module ?: "",
> > + tp->module ? ":" : "", tp->symbol, tp->offset);
> >
> > - for (i = 0; i < tev->nargs; i++) {
> > - ret = synthesize_probe_trace_arg(&tev->args[i], buf + len,
> > - MAX_CMDLEN - len);
> > - if (ret <= 0)
> > + for (i = 0; i < tev->nargs; i++)
> > + if (synthesize_probe_trace_arg(&tev->args[i], &buf) < 0)
> > goto error;
> > - len += ret;
> > - }
> >
> > - return buf;
> > + ret = strbuf_detach(&buf, NULL);
> > error:
> > - free(buf);
> > - return NULL;
> > + strbuf_release(&buf);
> > + return ret;
> > }
> >
> > static int find_perf_probe_point_from_map(struct probe_trace_point *tp,
> > @@ -1958,7 +1882,7 @@ static int convert_to_perf_probe_point(struct probe_trace_point *tp,
> > static int convert_to_perf_probe_event(struct probe_trace_event *tev,
> > struct perf_probe_event *pev, bool is_kprobe)
> > {
> > - char buf[64] = "";
> > + struct strbuf buf = STRBUF_INIT;
> > int i, ret;
> >
> > /* Convert event/group name */
> > @@ -1981,9 +1905,9 @@ static int convert_to_perf_probe_event(struct probe_trace_event *tev,
> > if (tev->args[i].name)
> > pev->args[i].name = strdup(tev->args[i].name);
> > else {
> > - ret = synthesize_probe_trace_arg(&tev->args[i],
> > - buf, 64);
> > - pev->args[i].name = strdup(buf);
> > + strbuf_init(&buf, 32);
> > + ret = synthesize_probe_trace_arg(&tev->args[i], &buf);
> > + pev->args[i].name = strbuf_detach(&buf, NULL);
> > }
> > if (pev->args[i].name == NULL && ret >= 0)
> > ret = -ENOMEM;
> > @@ -2161,37 +2085,37 @@ static int perf_probe_event__sprintf(const char *group, const char *event,
> > const char *module,
> > struct strbuf *result)
> > {
> > - int i, ret;
> > - char buf[128];
> > - char *place;
> > + int i;
> > + char *buf;
> >
> > - /* Synthesize only event probe point */
> > - place = synthesize_perf_probe_point(&pev->point);
> > - if (!place)
> > - return -EINVAL;
> > + if (asprintf(&buf, "%s:%s", group, event) < 0)
> > + return -errno;
> > + strbuf_addf(result, " %-20s (on ", buf);
> > + free(buf);
> >
> > - ret = e_snprintf(buf, 128, "%s:%s", group, event);
> > - if (ret < 0)
> > - goto out;
> > + /* Synthesize only event probe point */
> > + buf = synthesize_perf_probe_point(&pev->point);
> > + if (!buf)
> > + return -ENOMEM;
> > + strbuf_addstr(result, buf);
> > + free(buf);
> >
> > - strbuf_addf(result, " %-20s (on %s", buf, place);
> > if (module)
> > strbuf_addf(result, " in %s", module);
> >
> > if (pev->nargs > 0) {
> > strbuf_add(result, " with", 5);
> > for (i = 0; i < pev->nargs; i++) {
> > - ret = synthesize_perf_probe_arg(&pev->args[i],
> > - buf, 128);
> > - if (ret < 0)
> > - goto out;
> > + buf = synthesize_perf_probe_arg(&pev->args[i]);
> > + if (!buf)
> > + return -ENOMEM;
> > strbuf_addf(result, " %s", buf);
> > + free(buf);
> > }
> > }
> > strbuf_addch(result, ')');
> > -out:
> > - free(place);
> > - return ret;
> > +
> > + return 0;
> > }
> >
> > /* Show an event */
> > diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
> > index e54e7b0..e220962 100644
> > --- a/tools/perf/util/probe-event.h
> > +++ b/tools/perf/util/probe-event.h
> > @@ -120,7 +120,7 @@ int parse_probe_trace_command(const char *cmd, struct probe_trace_event *tev);
> > /* Events to command string */
> > char *synthesize_perf_probe_command(struct perf_probe_event *pev);
> > char *synthesize_probe_trace_command(struct probe_trace_event *tev);
> > -int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf, size_t len);
> > +char *synthesize_perf_probe_arg(struct perf_probe_arg *pa);
> >
> > /* Check the perf_probe_event needs debuginfo */
> > bool perf_probe_event_need_dwarf(struct perf_probe_event *pev);
> > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> > index b3bd0fb..9f68875 100644
> > --- a/tools/perf/util/probe-finder.c
> > +++ b/tools/perf/util/probe-finder.c
> > @@ -553,7 +553,7 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
> > static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
> > {
> > Dwarf_Die vr_die;
> > - char buf[32], *ptr;
> > + char *buf, *ptr;
> > int ret = 0;
> >
> > /* Copy raw parameters */
> > @@ -563,13 +563,13 @@ static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
> > if (pf->pvar->name)
> > pf->tvar->name = strdup(pf->pvar->name);
> > else {
> > - ret = synthesize_perf_probe_arg(pf->pvar, buf, 32);
> > - if (ret < 0)
> > - return ret;
> > + buf = synthesize_perf_probe_arg(pf->pvar);
> > + if (!buf)
> > + return -ENOMEM;
> > ptr = strchr(buf, ':'); /* Change type separator to _ */
> > if (ptr)
> > *ptr = '_';
> > - pf->tvar->name = strdup(buf);
> > + pf->tvar->name = buf;
> > }
> > if (pf->tvar->name == NULL)
> > return -ENOMEM;
> > @@ -1334,8 +1334,8 @@ static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
> > if (ret2 == 0) {
> > strlist__add(vl->vars,
> > strbuf_detach(&buf, NULL));
> > - }
> > - strbuf_release(&buf);
> > + } else
> > + strbuf_release(&buf);
> > }
> > }
> >
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>