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Subject[PATCH 4/8] perf stat: fix NULL pointer reference bug with event unit
Date
From: Stephane Eranian <eranian@google.com>

This patch fixes a problem with the handling of the newly introduced
optional event unit. The following cmdline caused a segfault:

$ perf stat -e cpu/event-0x3c/ ls

This patch fixes the problem with the default setting for alias->unit
which was eventually causing the segfault.

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1389972846-6566-2-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/parse-events.c | 2 +-
tools/perf/util/pmu.c | 24 ++++++++++++++++++++----
tools/perf/util/pmu.h | 2 +-
3 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index a7f1b6a91fdd..d248fca6d7ed 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -635,7 +635,7 @@ int parse_events_add_pmu(struct list_head *list, int *idx,
struct perf_event_attr attr;
struct perf_pmu *pmu;
struct perf_evsel *evsel;
- char *unit;
+ const char *unit;
double scale;

pmu = perf_pmu__find(name);
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index d9cab4d27192..b752ecb40d86 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -105,7 +105,7 @@ static int perf_pmu__parse_scale(struct perf_pmu_alias *alias, char *dir, char *
char scale[128];
int fd, ret = -1;
char path[PATH_MAX];
- char *lc;
+ const char *lc;

snprintf(path, PATH_MAX, "%s/%s.scale", dir, name);

@@ -609,7 +609,7 @@ static struct perf_pmu_alias *pmu_find_alias(struct perf_pmu *pmu,


static int check_unit_scale(struct perf_pmu_alias *alias,
- char **unit, double *scale)
+ const char **unit, double *scale)
{
/*
* Only one term in event definition can
@@ -634,14 +634,18 @@ static int check_unit_scale(struct perf_pmu_alias *alias,
* defined for the alias
*/
int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms,
- char **unit, double *scale)
+ const char **unit, double *scale)
{
struct parse_events_term *term, *h;
struct perf_pmu_alias *alias;
int ret;

+ /*
+ * Mark unit and scale as not set
+ * (different from default values, see below)
+ */
*unit = NULL;
- *scale = 0;
+ *scale = 0.0;

list_for_each_entry_safe(term, h, head_terms, list) {
alias = pmu_find_alias(pmu, term);
@@ -658,6 +662,18 @@ int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms,
list_del(&term->list);
free(term);
}
+
+ /*
+ * if no unit or scale foundin aliases, then
+ * set defaults as for evsel
+ * unit cannot left to NULL
+ */
+ if (*unit == NULL)
+ *unit = "";
+
+ if (*scale == 0.0)
+ *scale = 1.0;
+
return 0;
}

diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 9183380e2038..8b64125a9281 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -29,7 +29,7 @@ int perf_pmu__config_terms(struct list_head *formats,
struct perf_event_attr *attr,
struct list_head *head_terms);
int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms,
- char **unit, double *scale);
+ const char **unit, double *scale);
struct list_head *perf_pmu__alias(struct perf_pmu *pmu,
struct list_head *head_terms);
int perf_pmu_wrap(void);
--
1.8.1.4


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