#include "compat.h"
#include "../libringbuffer/tlsfixup.h"
#include "lttng-ust-baddr.h"
+#include "getenv.h"
/*
* Has lttng ust comm constructor been called ?
*
* ust_exit_mutex must never nest in ust_mutex.
*
+ * ust_fork_mutex must never nest in ust_mutex.
+ *
* ust_mutex_nest is a per-thread nesting counter, allowing the perf
* counter lazy initialization called by events within the statedump,
* which traces while the ust_mutex is held.
+ *
+ * ust_lock nests within the dynamic loader lock (within glibc) because
+ * it is taken within the library constructor.
*/
static pthread_mutex_t ust_mutex = PTHREAD_MUTEX_INITIALIZER;
*/
static pthread_mutex_t ust_exit_mutex = PTHREAD_MUTEX_INITIALIZER;
+/*
+ * ust_fork_mutex protects base address statedump tracing against forks. It
+ * prevents the dynamic loader lock to be taken (by base address statedump
+ * tracing) while a fork is happening, thus preventing deadlock issues with
+ * the dynamic loader lock.
+ */
+static pthread_mutex_t ust_fork_mutex = PTHREAD_MUTEX_INITIALIZER;
+
/* Should the ust comm thread quit ? */
static int lttng_ust_comm_should_quit;
{
const char *val;
- val = (const char *) getenv("LTTNG_HOME");
+ val = (const char *) lttng_secure_getenv("LTTNG_HOME");
if (val != NULL) {
return val;
}
- return (const char *) getenv("HOME");
+ return (const char *) lttng_secure_getenv("HOME");
}
/*
asm volatile ("" : : "m" (URCU_TLS(ust_mutex_nest)));
}
+/*
+ * Fixup urcu bp TLS.
+ */
+static
+void lttng_fixup_urcu_bp_tls(void)
+{
+ rcu_read_lock();
+ rcu_read_unlock();
+}
+
int lttng_get_notify_socket(void *owner)
{
struct sock_info *info = owner;
/*
* Get notify_sock timeout, in ms.
- * -1: don't wait. 0: wait forever. >0: timeout, in ms.
+ * -1: wait forever. 0: don't wait. >0: timeout, in ms.
*/
static
long get_timeout(void)
}
/*
- * Return values: -1: don't wait. 0: wait forever. 1: timeout wait.
+ * Return values: -1: wait forever. 0: don't wait. 1: timeout wait.
*/
static
int get_constructor_timeout(struct timespec *constructor_timeout)
*/
ret = clock_gettime(CLOCK_REALTIME, constructor_timeout);
if (ret) {
- return -1;
+ /* Don't wait. */
+ return 0;
}
constructor_timeout->tv_sec += constructor_delay_ms / 1000UL;
constructor_timeout->tv_nsec +=
constructor_timeout->tv_sec++;
constructor_timeout->tv_nsec -= 1000000000UL;
}
+ /* Timeout wait (constructor_delay_ms). */
return 1;
}
if (ctor_passed && sock_info->statedump_pending) {
sock_info->statedump_pending = 0;
+ pthread_mutex_lock(&ust_fork_mutex);
lttng_handle_pending_statedump(sock_info);
+ pthread_mutex_unlock(&ust_fork_mutex);
}
}
* to be the dynamic linker mutex) and ust_lock, taken within
* the ust lock.
*/
+ lttng_fixup_urcu_bp_tls();
lttng_fixup_ringbuffer_tls();
lttng_fixup_vtid_tls();
lttng_fixup_nest_count_tls();
if (ret == -1) {
PERROR("sigprocmask");
}
+
+ pthread_mutex_lock(&ust_fork_mutex);
+
ust_lock_nocheck();
rcu_bp_before_fork();
}
DBG("process %d", getpid());
ust_unlock();
+
+ pthread_mutex_unlock(&ust_fork_mutex);
+
/* Restore signals */
ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL);
if (ret == -1) {