Re: [PATCH 1/3] perf probe: Fix error message if get_real_path() failed

[Arnaldo Carvalho de Melo <acme@redhat.com>]

Em Fri, Jul 16, 2010 at 01:38:59AM +0900, Masami Hiramatsu escreveu:
> Hi Arnaldo,
> 
> Could you please merge this series, because this series
> fixes some bugs which people easily hit ?

I'll take a look at it, thanks for pointing it out.

- Arnaldo
 
> Thank you,
> 
> Chase Douglas wrote:
> > On Fri, 2010-07-09 at 18:28 +0900, Masami Hiramatsu wrote:
> >> Perf probe -L shows incorrect error message (Dwarf error)
> >> if it fails to find source file. This can confuse users.
> >>
> >> # ./perf probe -s /nowhere -L vfs_read
> >> Debuginfo analysis failed. (-2)
> >>   Error: Failed to show lines. (-2)
> >>
> >> With this patch, it shows correct message.
> >>
> >> # ./perf probe -s /nowhere -L vfs_read
> >> Failed to find source file. (-2)
> >>   Error: Failed to show lines. (-2)
> >>
> >> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> >> Cc: Chase Douglas <chase.douglas@canonical.com>
> >> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> >> Cc: Ingo Molnar <mingo@elte.hu>
> >> ---
> >>
> >>  tools/perf/util/probe-event.c  |   59 +++++++++++++++++++++++++++++++++++++++
> >>  tools/perf/util/probe-finder.c |   61 +++-------------------------------------
> >>  2 files changed, 64 insertions(+), 56 deletions(-)
> >>
> >> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> >> index 09cf546..8d08e75 100644
> >> --- a/tools/perf/util/probe-event.c
> >> +++ b/tools/perf/util/probe-event.c
> >> @@ -195,6 +195,55 @@ static int try_to_find_kprobe_trace_events(struct perf_probe_event *pev,
> >>  	return ntevs;
> >>  }
> >>
> >> +/*
> >> + * 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, char **new_path)
> >> +{
> >> +	if (!symbol_conf.source_prefix) {
> >> +		if (access(raw_path, R_OK) == 0) {
> >> +			*new_path = strdup(raw_path);
> >> +			return 0;
> >> +		} else
> >> +			return -errno;
> >> +	}
> >> +
> >> +	*new_path = malloc((strlen(symbol_conf.source_prefix) +
> >> +			    strlen(raw_path) + 2));
> >> +	if (!*new_path)
> >> +		return -ENOMEM;
> >> +
> >> +	for (;;) {
> >> +		sprintf(*new_path, "%s/%s", symbol_conf.source_prefix,
> >> +			raw_path);
> >> +
> >> +		if (access(*new_path, R_OK) == 0)
> >> +			return 0;
> >> +
> >> +		switch (errno) {
> >> +		case ENAMETOOLONG:
> >> +		case ENOENT:
> >> +		case EROFS:
> >> +		case EFAULT:
> >> +			raw_path = strchr(++raw_path, '/');
> >> +			if (!raw_path) {
> >> +				free(*new_path);
> >> +				*new_path = NULL;
> >> +				return -ENOENT;
> >> +			}
> >> +			continue;
> >> +
> >> +		default:
> >> +			free(*new_path);
> >> +			*new_path = NULL;
> >> +			return -errno;
> >> +		}
> >> +	}
> >> +}
> >> +
> >>  #define LINEBUF_SIZE 256
> >>  #define NR_ADDITIONAL_LINES 2
> >>
> >> @@ -244,6 +293,7 @@ int show_line_range(struct line_range *lr)
> >>  	struct line_node *ln;
> >>  	FILE *fp;
> >>  	int fd, ret;
> >> +	char *tmp;
> >>
> >>  	/* Search a line range */
> >>  	ret = init_vmlinux();
> >> @@ -266,6 +316,15 @@ int show_line_range(struct line_range *lr)
> >>  		return ret;
> >>  	}
> >>
> >> +	/* Convert source file path */
> >> +	tmp = lr->path;
> >> +	ret = get_real_path(tmp, &lr->path);
> >> +	free(tmp);	/* Free old path */
> >> +	if (ret < 0) {
> >> +		pr_warning("Failed to find source file. (%d)\n", ret);
> >> +		return ret;
> >> +	}
> >> +
> >>  	setup_pager();
> >>
> >>  	if (lr->function)
> >> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> >> index 3e64e1f..a934a36 100644
> >> --- a/tools/perf/util/probe-finder.c
> >> +++ b/tools/perf/util/probe-finder.c
> >> @@ -58,55 +58,6 @@ static int strtailcmp(const char *s1, const char *s2)
> >>  	return 0;
> >>  }
> >>
> >> -/*
> >> - * 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, char **new_path)
> >> -{
> >> -	if (!symbol_conf.source_prefix) {
> >> -		if (access(raw_path, R_OK) == 0) {
> >> -			*new_path = strdup(raw_path);
> >> -			return 0;
> >> -		} else
> >> -			return -errno;
> >> -	}
> >> -
> >> -	*new_path = malloc((strlen(symbol_conf.source_prefix) +
> >> -			    strlen(raw_path) + 2));
> >> -	if (!*new_path)
> >> -		return -ENOMEM;
> >> -
> >> -	for (;;) {
> >> -		sprintf(*new_path, "%s/%s", symbol_conf.source_prefix,
> >> -			raw_path);
> >> -
> >> -		if (access(*new_path, R_OK) == 0)
> >> -			return 0;
> >> -
> >> -		switch (errno) {
> >> -		case ENAMETOOLONG:
> >> -		case ENOENT:
> >> -		case EROFS:
> >> -		case EFAULT:
> >> -			raw_path = strchr(++raw_path, '/');
> >> -			if (!raw_path) {
> >> -				free(*new_path);
> >> -				*new_path = NULL;
> >> -				return -ENOENT;
> >> -			}
> >> -			continue;
> >> -
> >> -		default:
> >> -			free(*new_path);
> >> -			*new_path = NULL;
> >> -			return -errno;
> >> -		}
> >> -	}
> >> -}
> >> -
> >>  /* Line number list operations */
> >>
> >>  /* Add a line to line number list */
> >> @@ -1256,13 +1207,11 @@ end:
> >>  static int line_range_add_line(const char *src, unsigned int lineno,
> >>  			       struct line_range *lr)
> >>  {
> >> -	int ret;
> >> -
> >> -	/* Copy real path */
> >> +	/* Copy source path */
> >>  	if (!lr->path) {
> >> -		ret = get_real_path(src, &lr->path);
> >> -		if (ret != 0)
> >> -			return ret;
> >> +		lr->path = strdup(src);
> >> +		if (lr->path == NULL)
> >> +			return -ENOMEM;
> >>  	}
> >>  	return line_list__add_line(&lr->line_list, lineno);
> >>  }
> >> @@ -1460,7 +1409,7 @@ int find_line_range(int fd, struct line_range *lr)
> >>  		}
> >>  		off = noff;
> >>  	}
> >> -	pr_debug("path: %lx\n", (unsigned long)lr->path);
> >> +	pr_debug("path: %s\n", lr->path);
> >>  	dwarf_end(dbg);
> >>
> >>  	return (ret < 0) ? ret : lf.found;
> > 
> > This seems fine to me. I don't think any functionality has really
> > changed, just moving the function into probe-event.c and printing out an
> > accurate error message.
> > 
> > Acked-by: Chase Douglas <chase.douglas@canonical.com>
> > 
> > Thanks!
> >