Re: [PATCH v2 26/26] perf hist: Fix srcline memory leak
From: Ian Rogers
Date: Mon Jun 12 2023 - 10:46:39 EST
On Mon, Jun 12, 2023 at 7:16 AM Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> wrote:
>
> Em Mon, Jun 12, 2023 at 11:13:59AM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Thu, Jun 08, 2023 at 04:28:23PM -0700, Ian Rogers escreveu:
> > > srcline isn't freed if it is SRCLINE_UNKNOWN. Avoid strduping in this
> > > case as such strdups are redundant and leak memory.
> >
> > The patch is ok as its what the rest of the code is doing, i.e. strcmp()
> > to check if a srcline is the unknown one, but how about the following
> > patch on top of yours?
>
> [acme@quaco perf-tools-next]$ strings ~/bin/perf | grep '??:0'
> ??:0
> SRCLINE_UNKNOWN ((char *) "??:0")
> [acme@quaco perf-tools-next]$
Agreed, the strcmps make me nervous as they won't distinguish heap
from a global meaning we could end up with things like pointers to
freed memory. The comparison with the global is always going to be
same imo.
Acked-by: Ian Rogers <irogers@xxxxxxxxxx>
Thanks,
Ian
> > From 5163e54c1ed3d476f6b4e7f938861039bd4eec7c Mon Sep 17 00:00:00 2001
> > From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> > Date: Mon, 12 Jun 2023 11:10:46 -0300
> > Subject: [PATCH 1/1] perf srcline: Optimize comparision against
> > SRCLINE_UNKNOWN
> >
> > This is a string constant that gets returned and then strcmp() around,
> > we can instead just do a pointer comparision.
> >
> > Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > Cc: Ian Rogers <irogers@xxxxxxxxxx>
> > Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> > Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> > Link: https://lore.kernel.org/lkml/
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> > ---
> > tools/perf/builtin-diff.c | 4 ++--
> > tools/perf/util/block-info.c | 4 ++--
> > tools/perf/util/hist.c | 2 +-
> > tools/perf/util/map.c | 2 +-
> > tools/perf/util/sort.c | 2 +-
> > tools/perf/util/srcline.c | 2 +-
> > 6 files changed, 8 insertions(+), 8 deletions(-)
> >
> > diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
> > index eec89567ae483604..e8a1b16aa5f83f4f 100644
> > --- a/tools/perf/builtin-diff.c
> > +++ b/tools/perf/builtin-diff.c
> > @@ -1378,8 +1378,8 @@ static int cycles_printf(struct hist_entry *he, struct hist_entry *pair,
> > end_line = map__srcline(he->ms.map, bi->sym->start + bi->end,
> > he->ms.sym);
> >
> > - if ((strncmp(start_line, SRCLINE_UNKNOWN, strlen(SRCLINE_UNKNOWN)) != 0) &&
> > - (strncmp(end_line, SRCLINE_UNKNOWN, strlen(SRCLINE_UNKNOWN)) != 0)) {
> > + if (start_line != SRCLINE_UNKNOWN &&
> > + end_line != SRCLINE_UNKNOWN) {
> > scnprintf(buf, sizeof(buf), "[%s -> %s] %4ld",
> > start_line, end_line, block_he->diff.cycles);
> > } else {
> > diff --git a/tools/perf/util/block-info.c b/tools/perf/util/block-info.c
> > index 08279b1b65e5a4b0..fe4c17248799f0a2 100644
> > --- a/tools/perf/util/block-info.c
> > +++ b/tools/perf/util/block-info.c
> > @@ -296,8 +296,8 @@ static int block_range_entry(struct perf_hpp_fmt *fmt, struct perf_hpp *hpp,
> > end_line = map__srcline(he->ms.map, bi->sym->start + bi->end,
> > he->ms.sym);
> >
> > - if ((strncmp(start_line, SRCLINE_UNKNOWN, strlen(SRCLINE_UNKNOWN)) != 0) &&
> > - (strncmp(end_line, SRCLINE_UNKNOWN, strlen(SRCLINE_UNKNOWN)) != 0)) {
> > + if (start_line != SRCLINE_UNKNOWN) &&
> > + end_line != SRCLINE_UNKNOWN) {
> > scnprintf(buf, sizeof(buf), "[%s -> %s]",
> > start_line, end_line);
> > } else {
> > diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
> > index 0a10bcc6ec95b5e0..3dc8a4968beb9c01 100644
> > --- a/tools/perf/util/hist.c
> > +++ b/tools/perf/util/hist.c
> > @@ -484,7 +484,7 @@ static int hist_entry__init(struct hist_entry *he,
> > goto err_infos;
> > }
> >
> > - if (he->srcline && strcmp(he->srcline, SRCLINE_UNKNOWN)) {
> > + if (he->srcline && he->srcline != SRCLINE_UNKNOWN) {
> > he->srcline = strdup(he->srcline);
> > if (he->srcline == NULL)
> > goto err_rawdata;
> > diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
> > index c77e2fce6a379e7f..f30d34903aa4eabe 100644
> > --- a/tools/perf/util/map.c
> > +++ b/tools/perf/util/map.c
> > @@ -496,7 +496,7 @@ int map__fprintf_srcline(struct map *map, u64 addr, const char *prefix,
> >
> > if (dso) {
> > char *srcline = map__srcline(map, addr, NULL);
> > - if (strncmp(srcline, SRCLINE_UNKNOWN, strlen(SRCLINE_UNKNOWN)) != 0)
> > + if (srcline != SRCLINE_UNKNOWN)
> > ret = fprintf(fp, "%s%s", prefix, srcline);
> > zfree_srcline(&srcline);
> > }
> > diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
> > index 047c3606802f5b7f..6aa1c7f2b4448b30 100644
> > --- a/tools/perf/util/sort.c
> > +++ b/tools/perf/util/sort.c
> > @@ -643,7 +643,7 @@ static char *hist_entry__get_srcfile(struct hist_entry *e)
> >
> > sf = __get_srcline(map__dso(map), map__rip_2objdump(map, e->ip),
> > e->ms.sym, false, true, true, e->ip);
> > - if (!strcmp(sf, SRCLINE_UNKNOWN))
> > + if (sf == SRCLINE_UNKNOWN)
> > return no_srcfile;
> > p = strchr(sf, ':');
> > if (p && *sf) {
> > diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
> > index b8e596528d7e7e5e..48a04f42b308b080 100644
> > --- a/tools/perf/util/srcline.c
> > +++ b/tools/perf/util/srcline.c
> > @@ -809,7 +809,7 @@ void zfree_srcline(char **srcline)
> > if (*srcline == NULL)
> > return;
> >
> > - if (strcmp(*srcline, SRCLINE_UNKNOWN))
> > + if (*srcline != SRCLINE_UNKNOWN)
> > free(*srcline);
> >
> > *srcline = NULL;
> > --
> > 2.39.2
> >
> >
> > > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> > > ---
> > > tools/perf/util/hist.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
> > > index 77cb2cc83bb9..cc6f7f51faa5 100644
> > > --- a/tools/perf/util/hist.c
> > > +++ b/tools/perf/util/hist.c
> > > @@ -484,7 +484,7 @@ static int hist_entry__init(struct hist_entry *he,
> > > goto err_infos;
> > > }
> > >
> > > - if (he->srcline) {
> > > + if (he->srcline && strcmp(he->srcline, SRCLINE_UNKNOWN)) {
> > > he->srcline = strdup(he->srcline);
> > > if (he->srcline == NULL)
> > > goto err_rawdata;
> > > --
> > > 2.41.0.162.gfafddb0af9-goog
> > >
> >
> > --
> >
> > - Arnaldo
>
> --
>
> - Arnaldo