+/*
+ * lttng_perf_lock - Protect lttng-ust perf counter data structures
+ *
+ * Nests within the ust_lock, and therefore within the libc dl lock.
+ * Therefore, we need to fixup the TLS before nesting into this lock.
+ * Nests inside RCU bp read-side lock. Protects against concurrent
+ * fork.
+ */
+static pthread_mutex_t ust_perf_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * Track whether we are tracing from a signal handler nested on an
+ * application thread.
+ */
+static DEFINE_URCU_TLS(int, ust_perf_mutex_nest);
+
+/*
+ * Force a read (imply TLS fixup for dlopen) of TLS variables.
+ */
+void lttng_ust_fixup_perf_counter_tls(void)
+{
+ asm volatile ("" : : "m" (URCU_TLS(ust_perf_mutex_nest)));
+}
+
+void lttng_perf_lock(void)
+{
+ sigset_t sig_all_blocked, orig_mask;
+ int ret;
+
+ if (lttng_ust_cancelstate_disable_push()) {
+ ERR("lttng_ust_cancelstate_disable_push");
+ }
+ sigfillset(&sig_all_blocked);
+ ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ if (!URCU_TLS(ust_perf_mutex_nest)++) {
+ /*
+ * Ensure the compiler don't move the store after the close()
+ * call in case close() would be marked as leaf.
+ */
+ cmm_barrier();
+ pthread_mutex_lock(&ust_perf_mutex);
+ }
+ ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+}
+
+void lttng_perf_unlock(void)
+{
+ sigset_t sig_all_blocked, orig_mask;
+ int ret;
+
+ sigfillset(&sig_all_blocked);
+ ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ /*
+ * Ensure the compiler don't move the store before the close()
+ * call, in case close() would be marked as leaf.
+ */
+ cmm_barrier();
+ if (!--URCU_TLS(ust_perf_mutex_nest)) {
+ pthread_mutex_unlock(&ust_perf_mutex);
+ }
+ ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ if (lttng_ust_cancelstate_disable_pop()) {
+ ERR("lttng_ust_cancelstate_disable_pop");
+ }
+}
+