perf symbols: Protect dso cache tree using dso->lock
The dso cache is accessed during dwarf callchain unwind and it might be
processed concurrently. Protect it under dso->lock.
Note that it doesn't protect dso_cache__find(). I think it's safe to
access to the cache tree without the lock since we don't delete nodes.
It it missed an existing node due to rotation, it'll find it during
dso_cache__insert() anyway.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1431909055-21442-27-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 482d602..666e1db 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -495,10 +495,12 @@
}
static void
-dso_cache__free(struct rb_root *root)
+dso_cache__free(struct dso *dso)
{
+ struct rb_root *root = &dso->data.cache;
struct rb_node *next = rb_first(root);
+ pthread_mutex_lock(&dso->lock);
while (next) {
struct dso_cache *cache;
@@ -507,10 +509,12 @@
rb_erase(&cache->rb_node, root);
free(cache);
}
+ pthread_mutex_unlock(&dso->lock);
}
-static struct dso_cache *dso_cache__find(const struct rb_root *root, u64 offset)
+static struct dso_cache *dso_cache__find(struct dso *dso, u64 offset)
{
+ const struct rb_root *root = &dso->data.cache;
struct rb_node * const *p = &root->rb_node;
const struct rb_node *parent = NULL;
struct dso_cache *cache;
@@ -529,17 +533,20 @@
else
return cache;
}
+
return NULL;
}
-static void
-dso_cache__insert(struct rb_root *root, struct dso_cache *new)
+static struct dso_cache *
+dso_cache__insert(struct dso *dso, struct dso_cache *new)
{
+ struct rb_root *root = &dso->data.cache;
struct rb_node **p = &root->rb_node;
struct rb_node *parent = NULL;
struct dso_cache *cache;
u64 offset = new->offset;
+ pthread_mutex_lock(&dso->lock);
while (*p != NULL) {
u64 end;
@@ -551,10 +558,17 @@
p = &(*p)->rb_left;
else if (offset >= end)
p = &(*p)->rb_right;
+ else
+ goto out;
}
rb_link_node(&new->rb_node, parent, p);
rb_insert_color(&new->rb_node, root);
+
+ cache = NULL;
+out:
+ pthread_mutex_unlock(&dso->lock);
+ return cache;
}
static ssize_t
@@ -572,6 +586,7 @@
dso_cache__read(struct dso *dso, u64 offset, u8 *data, ssize_t size)
{
struct dso_cache *cache;
+ struct dso_cache *old;
ssize_t ret;
do {
@@ -591,7 +606,12 @@
cache->offset = cache_offset;
cache->size = ret;
- dso_cache__insert(&dso->data.cache, cache);
+ old = dso_cache__insert(dso, cache);
+ if (old) {
+ /* we lose the race */
+ free(cache);
+ cache = old;
+ }
ret = dso_cache__memcpy(cache, offset, data, size);
@@ -608,7 +628,7 @@
{
struct dso_cache *cache;
- cache = dso_cache__find(&dso->data.cache, offset);
+ cache = dso_cache__find(dso, offset);
if (cache)
return dso_cache__memcpy(cache, offset, data, size);
else
@@ -964,7 +984,7 @@
dso__data_close(dso);
auxtrace_cache__free(dso->auxtrace_cache);
- dso_cache__free(&dso->data.cache);
+ dso_cache__free(dso);
dso__free_a2l(dso);
zfree(&dso->symsrc_filename);
pthread_mutex_destroy(&dso->lock);