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Message-ID: <20160426145934.GE11033@kernel.org>
Date: Tue, 26 Apr 2016 11:59:34 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Masami Hiramatsu <mhiramat@...nel.org>
Cc: linux-kernel@...r.kernel.org, Namhyung Kim <namhyung@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Hemant Kumar <hemant@...ux.vnet.ibm.com>,
Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>
Subject: Re: [PATCH perf/core v4 01/19] perf probe: Use strbuf for making
strings
Em Tue, Apr 26, 2016 at 11:40:47PM +0900, Masami Hiramatsu escreveu:
> On Tue, 26 Apr 2016 10:36:57 -0300
> Arnaldo Carvalho de Melo <acme@...nel.org> wrote:
>
> > Em Tue, Apr 26, 2016 at 06:02:11PM +0900, Masami Hiramatsu escreveu:
> > > From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> > >
> > > 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.
What I don't like is that xrealloc ends up calling die() :-\ It should
instead propagate back the error.
In lots of cases I managed to use what is in glibc, asprintf(), that
will allocate space and format in one go.
But strbuf has this addf() one that indeed is handy. So I think I'll
take this patch as it is not for the simpler cases where asprintf() can
be used.
- Arnaldo
> Thank you,
>
> >
> > - Arnaldo
> >
> > > Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> > > Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> > >
> > > ---
> > > 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@...nel.org>
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