[PATCH 1/2] perf stat: fix NULL pointer reference bug with event unit

[Stephane Eranian]

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 <eran...@google.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 a7f1b6a..d248fca 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 d9cab4d..b752ecb 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 9183380..8b64125 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);
-- 
1.7.9.5

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