Re: [PATCH v2] perf probe: Find compilation directory path for lazy matching

From: Arnaldo Carvalho de Melo
Date: Wed Mar 11 2015 - 09:35:09 EST


Em Wed, Mar 04, 2015 at 09:34:38PM +0900, Masami Hiramatsu escreveu:
> (2015/03/04 16:52), Naohiro Aota wrote:
> > If we use lazy matching, it failed to open a souce file if perf command
> > is invoked outside of compilation directory:
> >
> > $ perf probe -a '__schedule;clear_*'
> > Failed to open kernel/sched/core.c: No such file or directory
> > Error: Failed to add events. (-2)
> >
> > OTOH, other commands like "probe -L" can solve the souce directory by
> > themselves. Let's make it possible for lazy matching too!
> >
>
> Looks good to me :)
>
> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>

This doesn't make sense... se below:

> Thank you!
>
> > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> > index 46f009a..e6c0262 100644
> > --- a/tools/perf/util/probe-finder.c
> > +++ b/tools/perf/util/probe-finder.c
> > @@ -849,11 +849,22 @@ static int probe_point_lazy_walker(const char *fname, int lineno,
> > static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
> > {
> > int ret = 0;
> > + char *fpath;
> >
> > if (intlist__empty(pf->lcache)) {
> > + const char *comp_dir;
> > +
> > + comp_dir = cu_get_comp_dir(&pf->cu_die);
> > + ret = get_real_path(pf->fname, comp_dir, &fpath);
> > + if (ret < 0) {
> > + pr_warning("Failed to find source file path.\n");
> > + return ret;
> > + }
> > +
> > /* Matching lazy line pattern */
> > - ret = find_lazy_match_lines(pf->lcache, pf->fname,
> > + ret = find_lazy_match_lines(pf->lcache, fpath,
> > pf->pev->point.lazy_line);
> > + free(fpath);
> > if (ret <= 0)
> > return ret;
> > }
> > @@ -1616,3 +1627,61 @@ found:
> > return (ret < 0) ? ret : lf.found;
> > }
> >
> > +/*
> > + * Find a src file from a DWARF tag path. Prepend optional source path prefix
> > + * and chop off leading directories that do not exist. Result is passed back as
> > + * a newly allocated path on success.
> > + * Return 0 if file was found and readable, -errno otherwise.
> > + */
> > +static int get_real_path(const char *raw_path, const char *comp_dir,
> > + char **new_path)

The function is marked "static"

> > +{
> > + const char *prefix = symbol_conf.source_prefix;
> > +
> > + if (!prefix) {
> > + if (raw_path[0] != '/' && comp_dir)
> > + /* If not an absolute path, try to use comp_dir */
> > + prefix = comp_dir;
> > + else {
> > + if (access(raw_path, R_OK) == 0) {
> > + *new_path = strdup(raw_path);
> > + return *new_path ? 0 : -ENOMEM;
> > + } else
> > + return -errno;
> > + }
> > + }
> > +
> > + *new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
> > + if (!*new_path)
> > + return -ENOMEM;
> > +
> > + for (;;) {
> > + sprintf(*new_path, "%s/%s", prefix, raw_path);
> > +
> > + if (access(*new_path, R_OK) == 0)
> > + return 0;
> > +
> > + if (!symbol_conf.source_prefix) {
> > + /* In case of searching comp_dir, don't retry */
> > + zfree(new_path);
> > + return -errno;
> > + }
> > +
> > + switch (errno) {
> > + case ENAMETOOLONG:
> > + case ENOENT:
> > + case EROFS:
> > + case EFAULT:
> > + raw_path = strchr(++raw_path, '/');
> > + if (!raw_path) {
> > + zfree(new_path);
> > + return -ENOENT;
> > + }
> > + continue;
> > +
> > + default:
> > + zfree(new_path);
> > + return -errno;
> > + }
> > + }
> > +}
> > diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
> > index 92590b2..5ef82dd 100644
> > --- a/tools/perf/util/probe-finder.h
> > +++ b/tools/perf/util/probe-finder.h
> > @@ -55,6 +55,10 @@ extern int debuginfo__find_available_vars_at(struct debuginfo *dbg,
> > struct variable_list **vls,
> > int max_points, bool externs);
> >
> > +/* Find a src file from a DWARF tag path */
> > +extern int get_real_path(const char *raw_path, const char *comp_dir,
> > + char **new_path);
> > +

And then you mark it "extern"? Have you tried to compile this? I tried:

CC /tmp/build/perf/tests/task-exit.o
util/probe-finder.c:1636:12: error: static declaration of âget_real_pathâ follows non-static declaration
static int get_real_path(const char *raw_path, const char *comp_dir,
^
In file included from util/probe-finder.c:41:0:
util/probe-finder.h:59:12: note: previous declaration of âget_real_pathâ was here
extern int get_real_path(const char *raw_path, const char *comp_dir,
^
util/probe-finder.c:1636:12: error: âget_real_pathâ defined but not used [-Werror=unused-function]
static int get_real_path(const char *raw_path, const char *comp_dir,
^
cc1: all warnings being treated as errors
make[3]: *** [/tmp/build/perf/util/probe-finder.o] Error 1
make[3]: *** Waiting for unfinished jobs....
CC /tmp/build/perf/tests/sw-clock.o

Also please refrain from using 'extern' in front of function prototypes, its just noise.

- Arnaldo

> > struct probe_finder {
> > struct perf_probe_event *pev; /* Target probe event */
> >
> >
>
>
> --
> Masami HIRAMATSU
> Software Platform Research Dept. Linux Technology Research Center
> Hitachi, Ltd., Yokohama Research Laboratory
> E-mail: masami.hiramatsu.pt@xxxxxxxxxxx
>
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