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Subject[PATCH 21/37] perf tools: Protect dso symbol loading using a mutex
Date
When multi-thread support for perf report is enabled, it's possible to
access a dso concurrently. Add a new pthread_mutex to protect it from
concurrent dso__load().

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/util/dso.c | 2 ++
tools/perf/util/dso.h | 1 +
tools/perf/util/symbol.c | 34 ++++++++++++++++++++++++----------
3 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 45be944d450a..3da75816b8f8 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -888,6 +888,7 @@ struct dso *dso__new(const char *name)
RB_CLEAR_NODE(&dso->rb_node);
INIT_LIST_HEAD(&dso->node);
INIT_LIST_HEAD(&dso->data.open_entry);
+ pthread_mutex_init(&dso->lock, NULL);
}

return dso;
@@ -917,6 +918,7 @@ void dso__delete(struct dso *dso)
dso_cache__free(&dso->data.cache);
dso__free_a2l(dso);
zfree(&dso->symsrc_filename);
+ pthread_mutex_destroy(&dso->lock);
free(dso);
}

diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index 3782c82c6e44..ac753594a469 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -102,6 +102,7 @@ struct dsos {
};

struct dso {
+ pthread_mutex_t lock;
struct list_head node;
struct rb_node rb_node; /* rbtree node sorted by long name */
struct rb_root symbols[MAP__NR_TYPES];
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index c24c5b83156c..6c764a5b3464 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1332,12 +1332,22 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
struct symsrc *syms_ss = NULL, *runtime_ss = NULL;
bool kmod;

- dso__set_loaded(dso, map->type);
+ pthread_mutex_lock(&dso->lock);
+
+ /* check again under the dso->lock */
+ if (dso__loaded(dso, map->type)) {
+ ret = 1;
+ goto out;
+ }
+
+ if (dso->kernel) {
+ if (dso->kernel == DSO_TYPE_KERNEL)
+ ret = dso__load_kernel_sym(dso, map, filter);
+ else if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
+ ret = dso__load_guest_kernel_sym(dso, map, filter);

- if (dso->kernel == DSO_TYPE_KERNEL)
- return dso__load_kernel_sym(dso, map, filter);
- else if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
- return dso__load_guest_kernel_sym(dso, map, filter);
+ goto out;
+ }

if (map->groups && map->groups->machine)
machine = map->groups->machine;
@@ -1350,18 +1360,18 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
struct stat st;

if (lstat(dso->name, &st) < 0)
- return -1;
+ goto out;

if (st.st_uid && (st.st_uid != geteuid())) {
pr_warning("File %s not owned by current user or root, "
"ignoring it.\n", dso->name);
- return -1;
+ goto out;
}

ret = dso__load_perf_map(dso, map, filter);
dso->symtab_type = ret > 0 ? DSO_BINARY_TYPE__JAVA_JIT :
DSO_BINARY_TYPE__NOT_FOUND;
- return ret;
+ goto out;
}

if (machine)
@@ -1369,7 +1379,7 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)

name = malloc(PATH_MAX);
if (!name)
- return -1;
+ goto out;

kmod = dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE ||
dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP ||
@@ -1450,7 +1460,11 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
out_free:
free(name);
if (ret < 0 && strstr(dso->name, " (deleted)") != NULL)
- return 0;
+ ret = 0;
+out:
+ dso__set_loaded(dso, map->type);
+ pthread_mutex_unlock(&dso->lock);
+
return ret;
}

--
2.1.3


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