static int initialized;
static void (*new_tracepoint_cb)(struct tracepoint *);
+/*
+ * tracepoint_mutex nests inside UST mutex.
+ *
+ * Note about interaction with fork/clone: UST does not hold the
+ * tracepoint mutex across fork/clone because it is either:
+ * - nested within UST mutex, in which case holding the UST mutex across
+ * fork/clone suffice,
+ * - taken by a library constructor, which should never race with a
+ * fork/clone if the application is expected to continue running with
+ * the same memory layout (no following exec()).
+ */
+static pthread_mutex_t tracepoint_mutex = PTHREAD_MUTEX_INITIALIZER;
+
/*
* libraries that contain tracepoints (struct tracepoint_lib).
- * Protected by UST lock.
+ * Protected by tracepoint mutex.
*/
static CDS_LIST_HEAD(libs);
/*
- * The UST lock protects the library tracepoints, the hash table, and
+ * The tracepoint mutex protects the library tracepoints, the hash table, and
* the library list.
- * All calls to the tracepoint API must be protected by the UST lock,
+ * All calls to the tracepoint API must be protected by the tracepoint mutex,
* excepts calls to tracepoint_register_lib and
- * tracepoint_unregister_lib, which take the UST lock themselves.
+ * tracepoint_unregister_lib, which take the tracepoint mutex themselves.
*/
/*
* Tracepoint hash table, containing the active tracepoints.
- * Protected by ust lock.
+ * Protected by tracepoint mutex.
*/
#define TRACEPOINT_HASH_BITS 6
#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
* Note about RCU :
* It is used to to delay the free of multiple probes array until a quiescent
* state is reached.
- * Tracepoint entries modifications are protected by the ust lock.
+ * Tracepoint entries modifications are protected by the tracepoint mutex.
*/
struct tracepoint_entry {
struct cds_hlist_node hlist;
/*
* Get tracepoint if the tracepoint is present in the tracepoint hash table.
- * Must be called with ust lock held.
+ * Must be called with tracepoint mutex held.
* Returns NULL if not present.
*/
static struct tracepoint_entry *get_tracepoint(const char *name)
/*
* Add the tracepoint to the tracepoint hash table. Must be called with
- * ust lock held.
+ * tracepoint mutex held.
*/
static struct tracepoint_entry *add_tracepoint(const char *name)
{
/*
* Remove the tracepoint from the tracepoint hash table. Must be called with
- * ust_lock held.
+ * tracepoint mutex held.
*/
static void remove_tracepoint(struct tracepoint_entry *e)
{
*
* Returns 0 if ok, error value on error.
* The probe address must at least be aligned on the architecture pointer size.
- * Called with the UST lock held.
+ * Called with the tracepoint mutex held.
*/
int __tracepoint_probe_register(const char *name, void *probe, void *data)
{
void *old;
+ int ret = 0;
+ pthread_mutex_lock(&tracepoint_mutex);
old = tracepoint_add_probe(name, probe, data);
- if (IS_ERR(old))
- return PTR_ERR(old);
+ if (IS_ERR(old)) {
+ ret = PTR_ERR(old);
+ goto end;
+ }
tracepoint_update_probes(); /* may update entry */
release_probes(old);
- return 0;
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
}
static void *tracepoint_remove_probe(const char *name, void *probe, void *data)
* @name: tracepoint name
* @probe: probe function pointer
* @probe: probe data pointer
- *
- * Called with the UST lock held.
*/
int __tracepoint_probe_unregister(const char *name, void *probe, void *data)
{
void *old;
+ int ret = 0;
+ pthread_mutex_lock(&tracepoint_mutex);
old = tracepoint_remove_probe(name, probe, data);
- if (IS_ERR(old))
- return PTR_ERR(old);
-
+ if (IS_ERR(old)) {
+ ret = PTR_ERR(old);
+ goto end;
+ }
tracepoint_update_probes(); /* may update entry */
release_probes(old);
- return 0;
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
}
static void tracepoint_add_old_probes(void *old)
* @probe: probe handler
*
* caller must call tracepoint_probe_update_all()
- * Called with the UST lock held.
*/
int tracepoint_probe_register_noupdate(const char *name, void *probe,
void *data)
{
void *old;
+ int ret = 0;
+ pthread_mutex_lock(&tracepoint_mutex);
old = tracepoint_add_probe(name, probe, data);
if (IS_ERR(old)) {
- return PTR_ERR(old);
+ ret = PTR_ERR(old);
+ goto end;
}
tracepoint_add_old_probes(old);
- return 0;
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
}
/**
* @probe: probe function pointer
*
* caller must call tracepoint_probe_update_all()
- * Called with the UST lock held.
+ * Called with the tracepoint mutex held.
*/
int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
void *data)
{
void *old;
+ int ret = 0;
+ pthread_mutex_lock(&tracepoint_mutex);
old = tracepoint_remove_probe(name, probe, data);
if (IS_ERR(old)) {
- return PTR_ERR(old);
+ ret = PTR_ERR(old);
+ goto end;
}
tracepoint_add_old_probes(old);
- return 0;
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
}
/**
* tracepoint_probe_update_all - update tracepoints
- * Called with the UST lock held.
*/
void tracepoint_probe_update_all(void)
{
CDS_LIST_HEAD(release_probes);
struct tp_probes *pos, *next;
+ pthread_mutex_lock(&tracepoint_mutex);
if (!need_update) {
- return;
+ goto end;
}
if (!cds_list_empty(&old_probes))
cds_list_replace_init(&old_probes, &release_probes);
synchronize_rcu();
free(pos);
}
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
}
void tracepoint_set_new_tracepoint_cb(void (*cb)(struct tracepoint *))
pl->tracepoints_start = tracepoints_start;
pl->tracepoints_count = tracepoints_count;
- ust_lock();
+ pthread_mutex_lock(&tracepoint_mutex);
/*
* We sort the libs by struct lib pointer address.
*/
/* TODO: update just the loaded lib */
lib_update_tracepoints();
- ust_unlock();
+ pthread_mutex_unlock(&tracepoint_mutex);
DBG("just registered a tracepoints section from %p and having %d tracepoints",
tracepoints_start, tracepoints_count);
struct tracepoint_lib *lib;
int tracepoints_count;
- ust_lock();
+ pthread_mutex_lock(&tracepoint_mutex);
cds_list_for_each_entry(lib, &libs, list) {
if (lib->tracepoints_start == tracepoints_start) {
struct tracepoint_lib *lib2free = lib;
DBG("just unregistered a tracepoints section from %p",
tracepoints_start);
end:
- ust_unlock();
+ pthread_mutex_unlock(&tracepoint_mutex);
return 0;
}
projects / lttng-ust.git / commitdiff
